Patent Publication Number: US-10782719-B2

Title: Capacitor-less voltage regulator, semiconductor device including the same and method of generating power supply voltage

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC § 119 to Korean Patent Application No. 10-2017-0160987, filed on Nov. 28, 2017 in the Korean Intellectual Property Office (KIPO), the contents of which are herein incorporated by reference in their entirety. 
     BACKGROUND 
     1. Technical Field 
     Example embodiments relate generally to semiconductor devices, and more particularly to voltage regulators that generate power supply voltages provided to semiconductor integrated circuits and operate without external capacitors, semiconductor devices including the voltage regulators, and methods of generating power supply voltages. 
     2. Description of the Related Art 
     Typically, a semiconductor device includes a semiconductor integrated circuit performing a particular function and a power supply circuit for powering the semiconductor integrated circuit. For example, a semiconductor memory device may include a memory cell array storing data and a voltage regulator supplying an operating voltage to the memory cell array. The voltage regulator has been driven with an external capacitor or an output capacitor that is connected to an output terminal of the voltage regulator and has a relatively large capacitance. Even if a load current flowing through a load is suddenly changed, a power supply voltage output from the voltage regulator may not be drastically changed due to the external capacitor, and the voltage regulator may stably provide the power supply voltage. However, the voltage regulator has occupied a significant amount of space in the semiconductor device due to the external capacitor. To reduce a size of a semiconductor device, researchers are conducting various research projects on techniques of a capacitor-less (or capless) voltage regulator that operates without an external capacitor. 
     SUMMARY 
     A voltage regulator includes a voltage converter configured to generate an output power supply voltage based on an input power supply voltage and an input reference voltage and provide the output power supply voltage to an external functional circuit, the voltage converter including an output terminal configured to output the output power supply voltage; and a sinker connected to the output terminal, the sinker configured to generate a sink current in response to a sink enable signal while the external functional circuit is not driven and configured to block generation of the sink current in response to an operating enable signal while the external functional circuit is driven, wherein the sink current corresponds to a load current that is to be consumed while the external functional circuit is driven. 
     A semiconductor device includes a functional circuit configured to operate based on an output power supply voltage; a voltage regulator configured to, generate the output power supply voltage based on an input power supply voltage and an input reference voltage, generate a sink current in response to a sink enable signal while the functional circuit is not driven, and block generation of the sink current in response to an operating enable signal while the functional circuit is driven; and a controller configured to control the functional circuit and the voltage regulator, wherein the sink current corresponds to a load current that is to be consumed while the functional circuit is driven. 
     A method of generating a power supply voltage includes generating an output power supply voltage based on an input power supply voltage and an input reference voltage and providing the output power supply voltage to an external functional circuit; generating a sink current in response to a sink enable signal while the external functional circuit is not driven; and blocking generation of the sink current in response to an operating enable signal while the external functional circuit is driven, wherein the sink current corresponds to a load current that is to be consumed while the external functional circuit is driven. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of example embodiments of the inventive concepts will become more apparent by describing in detail example embodiments of the inventive concepts with reference to the attached drawings. The accompanying drawings are intended to depict example embodiments of the inventive concepts and should not be interpreted to limit the intended scope of the claims. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
         FIG. 1  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
         FIG. 2  is a timing diagram for describing an operation of a voltage regulator according to at least some example embodiments of the inventive concepts. 
         FIG. 3  is a circuit diagram illustrating an example of a voltage converter that is included in a voltage regulator according to at least some example embodiments of the inventive concepts. 
         FIG. 4  is a block diagram illustrating an example of a sink logic circuit that is included in the voltage regulator of  FIG. 1 . 
         FIG. 5  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
         FIG. 6  is a timing diagram for describing an operation of a high voltage clamper that is included in the voltage regulator of  FIG. 5 . 
         FIG. 7  is a block diagram illustrating an example of a sink logic circuit that is included in the voltage regulator of  FIG. 5 . 
         FIG. 8  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
         FIG. 9  is a timing diagram for describing an operation of a clock generator that is included in the voltage regulator of  FIG. 8 . 
         FIG. 10  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
         FIG. 11  is a block diagram illustrating a semiconductor device according to at least some example embodiments of the inventive concepts. 
         FIGS. 12, 13 and 14  are flow charts illustrating a method of generating a power supply voltage according to at least some example embodiments of the inventive concepts. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     As is traditional in the field of the inventive concepts, embodiments are described, and illustrated in the drawings, in terms of functional blocks, units and/or modules. Those skilled in the art will appreciate that these blocks, units and/or modules are physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, microprocessors, hard-wired circuits, memory elements, wiring connections, and the like, which may be formed using semiconductor-based fabrication techniques or other manufacturing technologies. In the case of the blocks, units and/or modules being implemented by microprocessors or similar, they may be programmed using software (e.g., microcode) to perform various functions discussed herein and may optionally be driven by firmware and/or software. Alternatively, each block, unit and/or module may be implemented by dedicated hardware, or as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Also, each block, unit and/or module of the embodiments may be physically separated into two or more interacting and discrete blocks, units and/or modules without departing from the scope of the inventive concepts. Further, the blocks, units and/or modules of the embodiments may be physically combined into more complex blocks, units and/or modules without departing from the scope of the inventive concepts. 
       FIG. 1  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
     Referring to  FIG. 1 , a voltage regulator  100  includes a voltage converter  110  and a sinker  120 . 
     The voltage converter  110  generates an output power supply voltage VDD_OUT based on an input power supply voltage VDD_IN and an input reference voltage VBREF. The voltage converter  110  includes an output terminal TOUT outputting the output power supply voltage VDD_OUT. The voltage converter  110  may have a configuration of generating a stable power supply voltage (e.g., stably generating the output power supply voltage VDD_OUT). A detailed configuration of the voltage converter  110  will be described with reference to  FIG. 3 . 
     The output power supply voltage VDD_OUT is provided to an external functional circuit  200  that is disposed or located outside the voltage regulator  100 . In other words, the functional circuit  200  may operate or may be driven based on the output power supply voltage VDD_OUT. Although not illustrated in  FIG. 1 , a driving clock signal may be additionally provided to the functional circuit  200 , and the functional circuit  200  may operate or may be driven based on the driving clock signal. In addition, while the functional circuit  200  operates or is driven based on the output power supply voltage VDD_OUT and/or the driving clock signal, a load current ILOAD may be consumed. 
     In some example embodiments, the functional circuit  200  may be any semiconductor integrated circuit performing specific or, alternatively, predetermined functions. For example, the functional circuit  200  may include a data storage circuit including, e.g., a memory cell array, a display control circuit, any signal processing circuit such as an image signal processing circuit, or the like. 
     The sinker  120  is connected to the output terminal TOUT via an output node NOUT. The sinker  120  generates a sink current ISINK in response to a sink enable signal SINK_EN while the functional circuit  200  is not driven. The sink current ISINK corresponds to the load current ILOAD that is to be consumed while the functional circuit  200  is driven. The sinker  120  blocks generation of the sink current ISINK in response to an operating enable signal OP_EN while the functional circuit  200  is driven. In other words, the sinker  120  and the functional circuit  200  may be complementarily enabled. While the functional circuit  200  is disabled (e.g., is not driven), the sinker  120  may be enabled to generate the sink current ISINK. While the functional circuit  200  is enabled (e.g., is driven), the sinker  120  may be disabled and may not generate the sink current ISINK. 
     According to at least some example embodiments of the inventive concepts, the amount of the load current ILOAD may be predetermined. For example, the amount of the load current ILOAD may be determined before the functional circuit  200  is manufactured in mass production (e.g., at a time point at which the functional circuit  200  is designed or experiment samples of the functional circuit  200  are manufactured). The voltage regulator  100  including the sinker  120  may be manufactured such that the sink current ISINK corresponding to the load current ILOAD is generated based on the predetermined amount of the load current ILOAD 
     In some example embodiments, the sinker  120  may include a current generator  130  and a sink logic circuit  140 . 
     The current generator  130  may be connected to the output terminal TOUT via the output node NOUT. The current generator  130  may generate the sink current ISINK in response to a first control signal CS 1 . The current generator  130  may include a plurality of current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n . The plurality of current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  may be connected in parallel between the output terminal TOUT (e.g., the output node NOUT) and a ground voltage. The plurality of current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  may be selectively turned on in response to the first control signal CS 1 . In  FIG. 1  and following drawings, an inverted triangle (e.g., V) connected to one electrode of a transistor or one end of a resistor may represent the ground voltage (e.g., GND or VSS voltage). 
     Each of the plurality of current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  may include a respective one of a plurality of resistors R 1 , R 2 , R 3 , . . . , RN and a respective one of a plurality of transistors T 1 , T 2 , T 3 , . . . , TN. For example, the first current level controller  130   a  may include the first resistor R 1  and the first transistor T 1 , the second current level controller  130   b  may include the second resistor R 2  and the second transistor T 2 , the third current level controller  130   c  may include the third resistor R 3  and the third transistor T 3 , and the N-th current level controller  130   n  may include the N-th resistor RN and the N-th transistor TN, where N is a natural number. Each of the plurality of resistors R 1 , R 2 , R 3 , . . . , RN may be connected to the output terminal TOUT via the output node NOUT. Each of the plurality of transistors T 1 , T 2 , T 3 , . . . , TN may be connected between a respective one of the plurality of resistors R 1 , R 2 , R 3 , . . . , RN and the ground voltage. Each of the plurality of transistors T 1 , T 2 , T 3 , . . . , TN may have a control electrode receiving the first control signal CS 1 . 
     The sink logic circuit  140  may generate the first control signal CS 1  based on a first clock signal CLK 1 , the sink enable signal SINK_EN and the operating enable signal OP_EN. For example, the operating enable signal OP_EN may be provided from the functional circuit  200 . A detailed configuration of the sink logic circuit  140  will be described with reference to  FIG. 4 . 
     In some example embodiments, the first control signal CS 1  may be an N-bit control signal. For example, first through N-th bits of the first control signal CS 1  may be applied to the control electrodes of the plurality of transistors T 1 , T 2 , T 3 , . . . , TN, respectively. For example, the N bits of the N-bit control signal CS 1  may be provided to the current generator  130  via N signal lines connected between the sink logic circuit  140  and the N transistors T 1 -TN, respectively, such that the N bits of the N-bit control signal CS 1  can be used to control the current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  independently. The number of turned-on current level controllers among the plurality of current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  (e.g., the number of turned-on transistors among the plurality of transistors T 1 , T 2 , T 3 , . . . , TN) may be adjusted or controlled based on the first control signal CS 1 , and thus the amount of the sink current ISINK may be adjusted or controlled. For example, the amount of the sink current ISINK may increase (or decrease) as the number of turned-on current level controllers increases (or decreases). 
     In some example embodiments, resistances of the plurality of resistors R 1 , R 2 , R 3 , . . . , RN may be substantially the same as or different from each other. 
       FIG. 2  is a timing diagram for describing an operation of a voltage regulator according to at least some example embodiments of the inventive concepts. 
     Referring to  FIGS. 1 and 2 , before time t 1 , the voltage converter  110  generates the output power supply voltage VDD_OUT having a target power level VDDT. 
     At time t 1 , the sink enable signal SINK_EN is activated by transitioning from a logic low level to a logic high level, and the sinker  120  is enabled. When the functional circuit  200  is to be driven or used, the sinker  120  is enabled to generate the sink current ISINK before the functional circuit  200  is enabled to perform specific or, alternatively, predetermined functions. 
     A level of the sink current ISINK scalariformly (e.g., gradationally, gradually, stage by stage or in stages) increases from a zero level ISN to a target level IST in response to an activation of the sink enable signal SINK_EN (e.g., in response to a rising edge of the sink enable signal SINK_EN). In this case, a level change or variation of the output power supply voltage VDD_OUT may be reduced or minimized by scalariformly increasing the level of the sink current ISINK. 
     The zero level ISN may represent non-generation of the sink current ISINK, and the target level IST may correspond to the load current ILOAD. For example, the zero level ISN may be about 0 mA, and the target level IST may correspond to an operating level ILO that is a level of the load current ILOAD while the functional circuit  200  actually operates or is driven. 
     Since the functional circuit  200  does not actually operate or is not actually driven at time t 1 , the operating enable signal OP_EN is deactivated to maintain a logic low level, and the load current ILOAD has a non-operating level ILN. In other words, the non-operating level ILN represents that the functional circuit  200  does not actually operate or is not actually driven. Unlike the zero level ISN, the non-operating level ILN may not be about 0 mA because a leakage current is generated by the functional circuit  200  even if the functional circuit  200  does not actually operate or is not actually driven. 
     At time t 2 , the functional circuit  200  is enabled and actually operates or is actually driven based on the output power supply voltage VDD_OUT, the operating enable signal OP_EN is activated by transitioning from a logic low level to a logic high level, and a level of the load current ILOAD instantaneously (e.g., immediately, instantly or in a moment) increases from the non-operating level ILN to the operating level ILO. The level of the sink current ISINK instantaneously decreases from the target level IST to the zero level ISN in response to an activation of the operating enable signal OP_EN (e.g., in response to a rising edge of the operating enable signal OP_EN). In other words, as the functional circuit  200  actually begins to operate or be driven at time t 2 , the load current ILOAD is drastically or suddenly changed (e.g., increases), and at the same time, the sink current ISINK is also drastically or suddenly changed (e.g., decreases). In addition, a level of the output power supply voltage VDD_OUT may be slightly changed or fluctuated according to the level change of the load current ILOAD and the sink current ISINK. 
     In some example embodiments, the amount of the sink current ISINK may be substantially the same as the amount of the load current ILOAD. For example, the changed amount of the sink current ISINK and the changed amount of the load current ILOAD according to the enablement of the functional circuit  200  may be substantially the same as each other. For example, a difference between the target level IST and the zero level ISN of the sink current ISINK may be substantially the same as a difference between the operating level ILO and the non-operating level ILN of the load current ILOAD. In other words, an increment of the load current ILOAD and a decrement of the sink current ISINK may be substantially the same as each other, and thus the amount of total current flowing through the output terminal TOUT or the output node NOUT may not be substantially changed and may be substantially maintained. 
     In other example embodiments, the amount of the sink current ISINK may be proportional to the amount of the load current ILOAD. 
     At time t 3 , the functional circuit  200  is disabled and does not operate or is not driven, the operating enable signal OP_EN is deactivated by transitioning from the logic high level to the logic low level, and the level of the load current ILOAD instantaneously decreases from the operating level ILO to the non-operating level ILN. The level of the sink current ISINK instantaneously increases from the zero level ISN to the target level IST in response to a deactivation of the operating enable signal OP_EN (e.g., in response to a falling edge of the operating enable signal OP_EN). In other words, as the functional circuit  200  stops operating or being driven at time t 3 , the load current ILOAD is drastically or suddenly changed (e.g., decreases), and at the same time, the sink current ISINK is also drastically or suddenly changed (e.g., increases). In addition, the level of the output power supply voltage VDD_OUT may be slightly changed or fluctuated according to the level change of the load current ILOAD and the sink current ISINK. 
     An operation at time t 4  and an operation at time t 5  may be substantially the same as the operation at time t 2  and the operation at time t 3 , respectively. 
     At time t 6 , the sink enable signal SINK_EN is deactivated by transitioning from the logic high level to the logic low level, and the sinker  120  is disabled. When it does not need to operate or be driven the functional circuit  200  anymore, the sinker  120  is disabled after the functional circuit  200  is disabled. 
     The level of the sink current ISINK scalariformly decreases from the target level IST to the zero level ISN in response to a deactivation of the sink enable signal SINK_EN (e.g., in response to a falling edge of the sink enable signal SINK_EN). In this case, a level change or variation of the output power supply voltage VDD_OUT may be reduced or minimized by scalariformly decreasing the level of the sink current ISINK. 
     In some example embodiments, an operation of determining whether the functional circuit  200  is to be driven and/or whether it does not need to be driven the functional circuit  200  anymore, e.g., an operation of determining the activation/deactivation of the sink enable signal SINK_EN may be performed by an external controller (e.g., a controller  50  in  FIG. 11 ). 
     The voltage regulator  100  according to at least some example embodiments of the inventive concepts may be implemented as a capacitor-less or a capless voltage regulator in which an external capacitor or an output capacitor connected to the output terminal TOUT or the output node NOUT is not used, and may include the sinker  120  for stabilizing the output power supply voltage VDD_OUT. The sinker  120  may be enabled in advance before the functional circuit  200  actually operates or is driven, and may scalariformly generate the sink current ISINK corresponding to the load current ILOAD that is predicted to be consumed while the functional circuit  200  is actually driven. When the functional circuit  200  is enabled and actually operates or is driven, and when the load current ILOAD is actually consumed by the functional circuit  200 , the sinker  120  may block the generation of the sink current ISINK. Accordingly, the amount of total current flowing through the output terminal TOUT or the output node NOUT may not be substantially changed and may be substantially maintained, the level change of the output power supply voltage VDD_OUT may be minimized or reduced, and the output power supply voltage VDD_OUT having a relatively stable level may be generated. 
       FIG. 3  is a circuit diagram illustrating an example of a voltage converter that is included in a voltage regulator according to at least some example embodiments of the inventive concepts. 
     Referring to  FIG. 3 , a voltage converter  110   a  may include an error amplifier  112 , a pass circuit  114 , a feedback circuit  116  and the output terminal TOUT. 
     In some example embodiments, the voltage converter  110   a  may be implemented as a linear regulator. The linear regulator has a linear relationship between an input voltage and an output voltage. Unlike a switching regulator, an output voltage of the linear regulator is controlled without switching operations. The linear regulator may have relatively simple structure and reduced noise. For example, the voltage converter  110   a  may be a low dropout (LDO) regulator. 
     The error amplifier  112  may compare the input reference voltage VBREF with a feedback voltage VFB to generate a pass control signal PS. The error amplifier  112  may include a first input terminal receiving the input reference voltage VBREF, a second input terminal connected to a feedback node NF and receiving the feedback voltage VFB, and an output terminal outputting the pass control signal PS. 
     In some example embodiments, the input reference voltage VBREF may be provided from an outside of the voltage regulator (e.g., from an external reference voltage generator). In other example embodiments, although not illustrated in  FIGS. 1 and 3 , the voltage converter  110   a  or the voltage regulator (e.g., the voltage regulator  100  of  FIG. 1 ) may include a reference voltage generator that generates the input reference voltage VBREF. For example, the input reference voltage VBREF may be a bandgap reference voltage. 
     The pass circuit  114  may generate the output power supply voltage VDD_OUT in response to the input power supply voltage VDD_IN and the pass control signal PS. The pass circuit  114  may include a pass transistor PT. The pass transistor PT may include a first electrode receiving the input power supply voltage VDD_IN, a control electrode receiving the pass control signal PS, and a second electrode connected to the output terminal TOUT and outputting the output power supply voltage VDD_OUT. 
     The feedback circuit  116  may generate the feedback voltage VFB based on the output power supply voltage VDD_OUT (e.g., by retrieving the output power supply voltage VDD_OUT from the output terminal TOUT). The feedback circuit  116  may include a plurality of resistors RF1 and RF2. The resistor RF1 may be connected between the output terminal TOUT and the feedback node NF, and the resistor RF2 may be connected between the feedback node NF and the ground voltage. 
     In the voltage regulator  100  according to at least some example embodiments of the inventive concepts, the output terminal TOUT of the voltage converter  110   a  may not be connected to an external capacitor having a relatively large capacitance (e.g., more than about 2 uF), and there may be only a parasitic capacitance (e.g., less than about 5 nF) at the output terminal TOUT that is caused by other elements (e.g., the pass transistor PT and/or the resistors RF1 and RF2). When the output power supply voltage VDD_OUT is generated only using the voltage converter  110   a , the output power supply voltage VDD_OUT may be drastically or suddenly changed as the load current ILOAD is drastically or suddenly changed. For example, a functional circuit (e.g., the functional circuit  200  in  FIG. 1 ) may be damaged or broken when the level of the output power supply voltage VDD_OUT becomes excessively high, and a malfunction of the functional circuit may be caused when the level of the output power supply voltage VDD_OUT becomes too low. As described with reference to  FIGS. 1 and 2 , when the output power supply voltage VDD_OUT is generated using the voltage converter  110   a  with the sinker  120  connected to the output terminal TOUT, the level change of the output power supply voltage VDD_OUT may be minimized or reduced, and the output power supply voltage VDD_OUT having a relatively stable level may be generated. 
     Although not illustrated in  FIG. 3 , the voltage converter included in the voltage regulator  100  according to at least some example embodiments of the inventive concepts may be implemented as any linear regulator, such as a shunt regulator, a series regulator, or the like. 
       FIG. 4  is a block diagram illustrating an example of a sink logic circuit that is included in the voltage regulator of  FIG. 1 . 
     Referring to  FIG. 4 , a sink logic circuit  140   a  may include a counter  142  and an output circuit  144 . 
     The counter  142  may generate a count signal CNT based on the first clock signal CLK 1  and the sink enable signal SINK_EN. A value of the count signal CNT may be sequentially increases or decreases. 
     In some example embodiments, the counter  142  may sequentially increase a value of the count signal CNT from a minimum value (e.g., zero) to a maximum value in response to the first clock signal CLK 1  and the activation of the sink enable signal SINK_EN (e.g., at time t 1  in  FIG. 2 ). After the value of the count signal CNT increases to reach the maximum value, the counter  142  may maintain the value of the count signal CNT to the maximum value while the activation of the sink enable signal SINK_EN is maintained. 
     In some example embodiments, the counter  142  may sequentially decrease the value of the count signal CNT from the maximum value to the minimum value in response to the first clock signal CLK 1  and the deactivation of the sink enable signal SINK_EN (e.g., at time t 6  in  FIG. 2 ). 
     In some example embodiments, the first clock signal CLK 1  may be provided from an outside of the voltage regulator (e.g., from an external oscillator). In other example embodiments, although not illustrated in  FIGS. 1 and 4 , the sink logic circuit  140   a  or the voltage regulator (e.g., the voltage regulator  100  of  FIG. 1 ) may include an oscillator that generates the first clock signal CLK 1 . 
     The output circuit  144  may generate the first control signal CS 1  based on the count signal CNT and the operating enable signal OP_EN. 
     In some example embodiments, the output circuit  144  may generate the first control signal CS 1  in response to the count signal CNT such that at least a part of the plurality of current level controllers is turned on (e.g., the plurality of current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  in  FIG. 1  are selectively turned on) based on the first control signal CS 1 . For example, as described with reference to  FIG. 1 , the first control signal CS 1  may be an N-bit control signal. The output circuit  144  may control or adjust bits of the first control signal CS 1  in response to the count signal CNT such that the number of turned-on current level controllers corresponds to the value of the count signal CNT. For example, when the value of the count signal CNT is the minimum value (e.g., zero), the output circuit  144  may set the bits of the first control signal CS 1  such that all of the current level controllers are turned off based on the first control signal CS 1 . When the value of the count signal CNT is “1,” the output circuit  144  may set the bits of the first control signal CS 1  such that only one current level controller is turned on based on the first control signal CS 1 . When the value of the count signal CNT is “2,” the output circuit  144  may set the bits of the first control signal CS 1  such that only two current level controllers are turned on based on the first control signal CS 1 . When the value of the count signal CNT is the maximum value (e.g., “N”), the output circuit  144  may set the bits of the first control signal CS 1  such that all of the current level controllers are turned on based on the first control signal CS 1 . For example, if each of the transistors T 1 , T 2 , T 3 , . . . , TN included in the current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  is a n-type metal oxide semiconductor (NMOS) transistor, and if the value of the count signal CNT is the maximum value, all of the bits of the first control signal CS 1  may be set to have “1” (e.g., a logic high level). 
     In some example embodiments, the output circuit  144  may generate the first control signal CS 1  in response to the activation of the operating enable signal OP_EN such that all of the plurality of current level controllers are turned off based on the first control signal CS 1 . For example, as described with reference to  FIG. 1 , the first control signal CS 1  may be an N-bit control signal. When the operating enable signal OP_EN is activated (e.g., at time t 2  in  FIG. 2 ), the output circuit  144  may set the bits of the first control signal CS 1  such that all of the current level controllers are turned off based on the first control signal CS 1  (e.g., the generation of the sink current ISINK is blocked), even if the value of the count signal CNT is not the minimum value. For example, if each of the transistors T 1 , T 2 , T 3 , . . . , TN included in the current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  is a NMOS transistor, and if the operating enable signal OP_EN is activated, all of the bits of the first control signal CS 1  may be set to have “0” (e.g., a logic low level). In other words, in an operation of controlling or adjusting the first control signal CS 1 , a priority of the operating enable signal OP_EN may be higher than a priority of the count signal CNT. 
     When the operating enable signal OP_EN is deactivated (e.g., at time t 3  in  FIG. 2 ), the output circuit  144  may generate the first control signal CS 1  in response to the count signal CNT again such that at least a part of the plurality of current level controllers is turned on based on the first control signal CS 1 . 
       FIG. 5  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
     Referring to  FIG. 5 , a voltage regulator  100   a  includes a voltage converter  110 , a sinker  120  and a high voltage clamper  160 . 
     The voltage regulator  100   a  of  FIG. 5  may be substantially the same as the voltage regulator  100  of  FIG. 1 , except that the voltage regulator  100   a  further includes the high voltage clamper  160 . Thus, repeated explanation will be omitted. 
     The high voltage clamper  160  may be connected to the output terminal TOUT via the output node NOUT. The high voltage clamper  160  may generate a second control signal CS 2  that is activated when a level of the output power supply voltage VDD_OUT is higher than a first reference level. The second control signal CS 2  may be provided to the sink logic circuit  140  included in the sinker  120 , and the sinker  120  may additionally control the generation of the sink current ISINK based on the second control signal CS 2 . 
     In some example embodiments, the high voltage clamper  160  may include a first voltage divider  162  and a first comparator  164 . 
     The first voltage divider  162  may be connected between the output terminal TOUT (e.g., the output node NOUT) and the ground voltage, and may generate a first voltage V 1  corresponding to the output power supply voltage VDD_OUT. 
     The first voltage divider  162  may include a plurality of resistors R 11 , R 12  and R 13 . The resistor R 11  may be connected between the output terminal TOUT (e.g., the output node NOUT) and a node N 1 . The resistors R 12  and R 13  may be connected in series between the node N 1  and the ground voltage. The number and resistances of the resistors R 11 , R 12  and R 13  may be changed according to at least some example embodiments of the inventive concepts. 
     The first comparator  164  may compare the first voltage V 1  with a first reference voltage VREF 1  to generate the second control signal CS 2 . The first comparator  164  may include a first input terminal connected to the node N 1  and receiving the first voltage V 1 , a second input terminal receiving the first reference voltage VREF 1 , and an output terminal outputting the second control signal CS 2 . 
     In some example embodiments, the first reference voltage VREF 1  may be provided from an outside of the voltage regulator  100   a  (e.g., from an external reference voltage generator). In other example embodiments, although not illustrated in  FIG. 5 , the high voltage clamper  160  or the voltage regulator  100   a  may include a reference voltage generator that generates the first reference voltage VREF 1 . 
     In some example embodiments, the first reference voltage VREF 1  and the input reference voltage VBREF may be substantially the same as or different from each other. 
       FIG. 6  is a timing diagram for describing an operation of a high voltage clamper that is included in the voltage regulator of  FIG. 5 . In  FIG. 6 , VDD_OUT′ represents an output power supply voltage in an example where the high voltage clamper  160  is not included in the voltage regulator, and VDD_OUT represents an output power supply voltage in an example where the high voltage clamper  160  is included in the voltage regulator  100   a  (e.g., in an example of  FIG. 5 ). 
     Referring to  FIGS. 5 and 6 , in the example where the high voltage clamper  160  is not included in the voltage regulator, a level of the output power supply voltage VDD_OUT′ may be drastically or suddenly changed with respect to the target power level VDDT and may become higher than a first reference level VTH 1 . In other words, an overshoot may occur on the output power supply voltage VDD_OUT′, and the functional circuit  200  may be damaged or broken if the level of the output power supply voltage VDD_OUT′ exceeds the upper limit. 
     In the example where the high voltage clamper  160  is included in the voltage regulator  100   a , the high voltage clamper  160  may activate the second control signal CS 2  when the level of the output power supply voltage VDD_OUT is higher than the first reference level VTH 1 . While the second control signal CS 2  is activated (e.g., while the second control signal CS 2  has a logic high level), the sinker  120  may generate the sink current ISINK with the maximum amount to reduce the level of the output power supply voltage VDD_OUT. 
     When the level of the output power supply voltage VDD_OUT is lower than or equal to the first reference level VTH 1 , the high voltage clamper  160  may deactivate the second control signal CS 2 . 
       FIG. 7  is a block diagram illustrating an example of a sink logic circuit that is included in the voltage regulator of  FIG. 5 . 
     Referring to  FIG. 7 , a sink logic circuit  140   b  may include a counter  142  and an output circuit  146 . 
     The counter  142  in  FIG. 7  may be substantially the same as the counter  142  in  FIG. 4 , and the output circuit  146  in  FIG. 7  may be substantially the same as the output circuit  144  in  FIG. 4 , except that the output circuit  146  operates further based on the second control signal CS 2 . Thus, repeated explanation will be omitted. 
     The output circuit  146  may generate the first control signal CS 1  based on the count signal CNT, the operating enable signal OP_EN and the second control signal CS 2 . 
     In some example embodiments, the output circuit  146  may generate the first control signal CS 1  in response to an activation of the second control signal CS 2  such that all of the plurality of current level controllers are turned on (e.g., all of the plurality of current level controllers  130   a ,  130   b ,  130   c , . . . ,  130   n  in  FIG. 1  are turned on) based on the first control signal CS 1 . For example, as described with reference to  FIG. 1 , the first control signal CS 1  may be an N-bit control signal. While the second control signal CS 2  is activated (e.g., during a time interval in which the second control signal CS 2  has the logic high level in  FIG. 6 ), the output circuit  146  may set the bits of the first control signal CS 1  such that all of the current level controllers are turned on based on the first control signal CS 1  (e.g., the sink current ISINK is generated with the maximum amount), even if the value of the count signal CNT is not the maximum value or even if the operating enable signal OP_EN is activated. In other words, in an operation of controlling or adjusting the first control signal CS 1 , a priority of the second control signal CS 2  may be higher than the priority of the operating enable signal OP_EN and the priority of the count signal CNT. 
     While the second control signal CS 2  is deactivated (e.g., during a time interval in which the second control signal CS 2  has the logic low level in  FIG. 6 ), the output circuit  146  may generate the first control signal CS 1  in response to the count signal CNT and the operating enable signal OP_EN again. 
       FIG. 8  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
     Referring to  FIG. 8 , a voltage regulator  100   b  includes a voltage converter  110 , a sinker  120  and a clock generator  180 . 
     The voltage regulator  100   b  of  FIG. 8  may be substantially the same as the voltage regulator  100  of  FIG. 1 , except that the voltage regulator  100   b  further includes the clock generator  180 . Thus, repeated explanation will be omitted. 
     The clock generator  180  may be connected to the output terminal TOUT via the output node NOUT. The clock generator  180  may generate a driving clock signal DCLK provided to the functional circuit  200  based on a second clock signal CLK 2  and a third control signal CS 3  that is activated when a level of the output power supply voltage VDD_OUT is lower than a second reference level. The functional circuit  200  may operate or may be driven based on the output power supply voltage VDD_OUT and the driving clock signal DCLK. 
     In some example embodiments, the second clock signal CLK 2  may be provided from an outside of the voltage regulator  100   b  (e.g., from an external oscillator). In other example embodiments, although not illustrated in  FIG. 8 , the clock generator  180  or the voltage regulator  100   b  may include an oscillator that generates the second clock signal CLK 2 . 
     In some example embodiments, the clock generator  180  may include a second voltage divider  182 , a second comparator  184  and an AND gate  186 . 
     The second voltage divider  182  may be connected between the output terminal TOUT (e.g., the output node NOUT) and the ground voltage, and may generate a second voltage V 2  corresponding to the output power supply voltage VDD_OUT. 
     The second voltage divider  182  may include a plurality of resistors R 21 , R 22  and R 23 . The resistor R 21  and R 22  may be connected in series between the output terminal TOUT (e.g., the output node NOUT) and a node N 2 . The resistor R 23  may be connected between the node N 2  and the ground voltage. The number and resistances of the resistors R 21 , R 22  and R 23  may be changed according to at least some example embodiments of the inventive concepts. 
     The second comparator  184  may compare the second voltage V 2  with a second reference voltage VREF 2  to generate the third control signal CS 3 . The second comparator  184  may include a first input terminal connected to the node N 2  and receiving the second voltage V 2 , a second input terminal receiving the second reference voltage VREF 2 , and an output terminal outputting the third control signal CS 3 . 
     In some example embodiments, the second reference voltage VREF 2  may be provided from an outside of the voltage regulator  100   b  (e.g., from an external reference voltage generator). In other example embodiments, although not illustrated in  FIG. 8 , the clock generator  180  or the voltage regulator  100   b  may include a reference voltage generator that generates the second reference voltage VREF 2 . 
     The AND gate  186  may generate the driving clock signal DCLK based on the second clock signal CLK 2  and the third control signal CS 3 . 
     The sink logic circuit  140  in  FIG. 8  may be substantially the same as the sink logic circuit  140   a  of  FIG. 4 . 
     In some example embodiments, the second reference voltage VREF 2  and the input reference voltage VBREF (or the first reference voltage VREF 1  in  FIG. 5 ) may be substantially the same as or different from each other. In some example embodiments, the second clock signal CLK 2  and the first clock signal CLK 1  may be substantially the same as or different from each other. 
       FIG. 9  is a timing diagram for describing an operation of a clock generator that is included in the voltage regulator of  FIG. 8 . 
     Referring to  FIGS. 8 and 9 , the level of the output power supply voltage VDD_OUT may be drastically or suddenly changed with respect to the target power level VDDT and may become lower than a second reference level VTH 2 . In other words, an undershoot may occur on the output power supply voltage VDD_OUT, and a malfunction of the functional circuit  200  may be caused if the level of the output power supply voltage VDD_OUT extends beyond the lower limit. According to at least some example embodiments of the inventive concepts, the second reference level VTH 2  may be different from the first reference level VTH 1  in  FIG. 6 . 
     The clock generator  180  may activate the third control signal CS 3  when the level of the output power supply voltage VDD_OUT is lower than the second reference level VTH 2 . While the third control signal CS 3  is activated (e.g., while the third control signal CS 3  has a logic low level), the clock generator  180  may block generation of the driving clock signal DCLK. For example, the AND gate  186  may perform an AND operation on the second clock signal CLK 2  and the third control signal CS 3  to generate the driving clock signal DCLK. Since the third control signal CS 3  has the logic low level, the driving clock signal DCLK output from the AND gate  186  may have a logic low level based on the logic low level of the third control signal CS 3 , regardless a level of the second clock signal CLK 2 . In other words, the clock generator  180  may perform a clock pause function to prevent the driving clock signal DCLK from toggling, and the functional circuit  200  may not operate or may not be driven while the generation of the driving clock signal DCLK is block. 
     When the level of the output power supply voltage VDD_OUT is higher than or equal to the second reference level VTH 2 , the clock generator  180  may deactivate the third control signal CS 3  and may generate the driving clock signal DCLK again. 
       FIG. 10  is a block diagram illustrating a voltage regulator according to at least some example embodiments of the inventive concepts. 
     Referring to  FIG. 10 , a voltage regulator  100   c  includes a voltage converter  110 , a sinker  120 , a high voltage clamper  160  and a clock generator  180 . 
     The voltage regulator  100   c  of  FIG. 10  may be substantially the same as the voltage regulator  100  of  FIG. 1 , except that the voltage regulator  100   c  further includes the high voltage clamper  160  and the clock generator  180 . The high voltage clamper  160  and the clock generator  180  in  FIG. 10  may be substantially the same as the high voltage clamper  160  in  FIG. 5  and the clock generator  180  in  FIG. 8 , respectively. Thus, repeated explanation will be omitted. 
     The sink logic circuit  140  in  FIG. 10  may be substantially the same as the sink logic circuit  140   b  of  FIG. 7 . 
     The voltage regulators  100   a ,  100   b  and  100   c  according to at least some example embodiments of the inventive concepts may be implemented as a capacitor-less or a capless voltage regulator, may include the sinker  120 , and may further include at least one of the high voltage clamper  160  and the clock generator  180 . The overshoot and undershoot on the output power supply voltage VDD_OUT may be prevented by the high voltage clamper  160  and the clock generator  180 . Accordingly, the output power supply voltage VDD_OUT having a relatively stable level may be generated. 
       FIG. 11  is a block diagram illustrating a semiconductor device according to at least some example embodiments of the inventive concepts. 
     Referring to  FIG. 11 , a semiconductor device  10  includes a voltage regulator  100 , a functional circuit  200  and a controller  50 . 
     The voltage regulator  100  and the functional circuit  200  in  FIG. 11  may be substantially the same as the voltage regulator  100  and the functional circuit  200  in  FIG. 1 , respectively. Thus, repeated explanation will be omitted. 
     The controller  50  controls the functional circuit  200  and the voltage regulator  100 . For example, the controller  50  may generate a control signal CONT for controlling an operation of the functional circuit  200 , and may generate the first clock signal CLK 1 , the sink enable signal SINK_EN and the operating enable signal OP_EN for controlling an operation of the voltage regulator  100 . Although not illustrated in  FIG. 11 , the controller  50  may further generate a driving clock signal provided to the functional circuit  200 . 
     Although  FIG. 11  illustrates an example where the operating enable signal OP_EN is provided from the controller  50 , according to at least some example embodiments, the operating enable signal OP_EN illustrated in  FIG. 11  may be provided to the sink logic circuit  140  from the functional circuit  200  instead of the controller  50 , as illustrated in  FIG. 1 . 
     In some example embodiments, the voltage regulator  100  in  FIG. 11  may be replaced with one of the voltage regulators  100   a ,  100   b  and  100   c  of  FIGS. 5, 8 and 10 . In this example, the controller  50  may further generate the second clock signal CLK 2  in  FIGS. 8 and 10 . 
     According to at least some example embodiments of the inventive concepts, the controller  50  may include or be implemented by one or more circuits or circuitry (e.g., hardware) specifically structured to carry out and/or control some or all of the operations described in the present disclosure as being performed by the controller  50 ; a memory and one or more processors executing computer-readable code (e.g., software and/or firmware) that is stored in the memory and includes instructions for causing the one or more processors to carry out and/or control some or all of the operations described in the present disclosure as being performed by the controller  50 ; or a combination of the above-referenced hardware and one or more processors executing computer-readable code. 
     Although not illustrated in  FIG. 11 , the semiconductor device  10  may further include a voltage generator that generates at least one of voltages (e.g., the input power supply voltage VDD_IN, the input reference voltage VBREF, the first reference voltage VREF 1 , the second reference voltage VREF 2 , etc.) provided to the voltage regulator  100 . 
       FIGS. 12, 13 and 14  are flow charts illustrating a method of generating a power supply voltage according to at least some example embodiments of the inventive concepts. 
     Referring to  FIGS. 1, 2 and 12 , in a method of generating (or stabilizing) a power supply voltage according to at least some example embodiments of the inventive concepts, the voltage converter  110  included in the voltage regulator  100  generates the output power supply voltage VDD_OUT based on the input power supply voltage VDD_IN and the input reference voltage VBREF (step S 100 ). 
     While the functional circuit  200  is not driven, the sinker  120  generates the sink current ISINK in response to the sink enable signal SINK_EN (step S 200 ). The sink current ISINK corresponds to the load current ILOAD that is to be consumed while the functional circuit  200  is driven. For example, as illustrated in  FIG. 2  (e.g., at time t 1 ), the sinker  120  may be enabled in advance in response to the activation of the sink enable signal SINK_EN before the functional circuit  200  is actually driven, and the sink current ISINK corresponding to the load current ILOAD may be scalariformly generated. 
     While the functional circuit  200  is driven, the sinker  120  blocks the generation of the sink current ISINK in response to the operating enable signal OP_EN (step S 300 ). For example, as illustrated in  FIG. 2  (e.g., at time t 2 ), the sinker  120  may be disabled in response to the activation of the operating enable signal OP_EN when the functional circuit  200  is actually driven and the load current ILOAD is actually consumed by the functional circuit  200 , and the generation of the sink current ISINK may be blocked. 
     After then, when the functional circuit  200  is not driven again, the sinker  120  may generate the sink current ISINK again in response to the deactivation of the operating enable signal OP_EN (e.g., at time t 3  in  FIG. 2 ). In addition, when it does not need to operate or be driven the functional circuit  200  anymore, the sinker  120  may scalariformly block the generation of the sink current ISINK in response to the deactivation of the sink enable signal SINK_EN (e.g., at time t 6  in  FIG. 2 ). 
     Referring to  FIGS. 5, 6 and 13 , steps S 100 , S 200  and S 300  in  FIG. 13  may be substantially the same as steps S 100 , S 200  and S 300  in  FIG. 12 , respectively. Thus, repeated explanation will be omitted. 
     When the level of the output power supply voltage VDD_OUT is higher than the first reference level VTH 1  (step S 400 : YES), the high voltage clamper  160  may activate the second control signal CS 2 . While the second control signal CS 2  is activated, the sinker  120  may control or adjust the sink current ISINK to reduce the level of the output power supply voltage VDD_OUT (step S 500 ). For example, the sinker  120  may generate the sink current ISINK with the maximum amount in response to the activated second control signal CS 2 . 
     When the level of the output power supply voltage VDD_OUT is lower than or equal to the first reference level VTH 1  (step S 400 : NO), steps S 200  and S 300  may be repeated. 
     Referring to  FIGS. 8, 9 and 14 , steps S 100 , S 200  and S 300  in  FIG. 14  may be substantially the same as steps S 100 , S 200  and S 300  in  FIG. 12 , respectively. Thus, repeated explanation will be omitted. 
     When the level of the output power supply voltage VDD_OUT is lower than the second reference level VTH 2  (step S 600 : YES), the clock generator  180  may activate the third control signal CS 3 . While the third control signal CS 3  is activated, the clock generator  180  may block generation of the driving clock signal DCLK (step S 700 ). For example, the clock generator  180  may prevent the driving clock signal DCLK from toggling in response to the activated third control signal CS 3 . 
     When the level of the output power supply voltage VDD_OUT is higher than or equal to the second reference level VTH 2  (step S 600 : NO), steps S 200  and S 300  may be repeated. 
     In some example embodiments, the method of generating the power supply voltage may be implemented with all of steps S 100 , S 200 , S 300 , S 400 , S 500 , S 600  and S 700 . 
     In some example embodiments, at least a part of the method of generating the power supply voltage may be implemented as hardware. In other example embodiments, at least a part of the method of generating the power supply voltage may be implemented as instructions or program routines (e.g., a software program). For example, the instructions or the program routines may be executed by a processor (not illustrated), and may be stored in a memory or storage (not illustrated). 
     The present disclosure may be used in various kinds of voltage regulators, or a device or a system including the voltage regulators, such as a personal computer, a laptop computer, a mobile phone, a smart phone, a tablet computer, a personal digital assistants (PDA), an enterprise digital assistant (EDA), a portable multimedia player (PMP), a digital camera, a music player, a portable game console, a navigation device, a wearable device, an internet of things (IoT) device, an internet of everything (IoE) device, an e-book, a virtual reality (VR) device, an augmented reality (AR) device, etc. 
     The voltage regulator according to at least some example embodiments of the inventive concepts may be implemented as a capacitor-less or a capless voltage regulator in which an external capacitor or an output capacitor connected to the output terminal is not used, and may include the sinker for stabilizing the output power supply voltage. The sinker may be enabled in advance before the functional circuit actually operates or is driven, and may scalariformly generate the sink current corresponding to the load current that is predicted to be consumed while the functional circuit is actually driven. When the functional circuit is enabled and actually operates or is driven, and when the load current is actually consumed by the functional circuit, the sinker may block the generation of the sink current. Accordingly, the amount of total current flowing through the output terminal may not be substantially changed and may be substantially maintained, the level change of the output power supply voltage may be minimized or reduced, and the output power supply voltage having a relatively stable level may be generated. 
     In addition, the voltage regulator according to at least some example embodiments of the inventive concepts may further include at least one of the high voltage clamper and the clock generator. The overshoot and undershoot on the output power supply voltage may be prevented by the high voltage clamper and the clock generator. Accordingly, the output power supply voltage having a relatively stable level may be generated. 
     Example embodiments of the inventive concepts having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the intended spirit and scope of example embodiments of the inventive concepts, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.