Abstract:
Provided is a semiconductor integrated circuit including a plurality of memory chips stacked therein. Each of the memory chips may include: a pumping enable signal control unit suitable for generating a pumping enable signal in response to a power-up signal or a trigger signal received from a first adjacent memory chip, delaying the pumping enable signal by a given time, and outputting the delayed pumping enable signal to a second adjacent memory chip; and a pumping unit suitable for generating a pumping voltage by performing a pumping operation in response to the pumping enable signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority of Korean Patent Application No. 10-2014-0158486, filed on Nov. 14, 2014, which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     This patent document relates to a semiconductor design technology, and more particularly, to a semiconductor integrated circuit including through-silicon vias (TSVs) and a method of driving the same. 
     2. Description of the Related Art 
     For integration of semiconductor integrated circuits, a variety of package technologies have been suggested. In particular, a chip stack in which a plurality of memory chips are stacked to form one semiconductor integrated circuit uses a through-electrode to transmit signals to a plurality of memory chips. Since memory chips are generally fabricated using silicon wafers, these through-electrodes are referred to as through silicon vias (TSVs). 
     Memory chips include power-up signal generation circuits for detecting whether external voltages, received from outside (e.g., an external device or source), reach a preset target level. The power-up signal generation circuit detects the level of the external voltage, and generates a power-up signal when the external voltage reaches the target level. The power-up signal contains information on whether the external voltage reaches the target level and is stabilized. Thus, an internal circuit of the memory chip receives the power-up signal and determines an operation period. During the power-up operation, a pumping operation must be performed to increase the external voltage, so that the internal circuits can operate. 
     When there are multiple memory chips, each of the memory chips detects external voltage level and generates a power-up signal. Thus, the power-up signal for each memory chip may be generated at the same or different times. Thus, it is difficult to predict the timing of generating the power-up signal due to process variations in each of the memory chips. Furthermore, when the power-up signals of the memory chips are equal, the pumping operations are performed at the same time, thereby increasing power consumption. As the power consumption of the memory chips increases, a failure may occur in memory chip operations due to unstable power. 
     SUMMARY 
     Various embodiments are directed to a semiconductor integrated circuit capable of reducing power consumption by performing pumping operations of a plurality of memory chips at different timings. 
     In an embodiment, there is provided a semiconductor integrated circuit including a plurality of memory chips stacked therein. Each of the memory chips may include: a pumping enable signal control unit suitable for generating a pumping enable signal in response to a power-up signal or a trigger signal received from a first adjacent memory chip, delaying the pumping enable signal by a given time, and outputting the delayed pumping enable signal to a second adjacent memory chip; and a pumping unit suitable for generating a pumping voltage by performing a pumping operation in response to the pumping enable signal. 
     Each of the memory chips may further include a receiving unit suitable for receiving the trigger signal from the first adjacent memory chip and outputting the received trigger signal to the pumping enable signal control unit, and a transmitting unit suitable for transmitting the delayed pumping enable signal, outputted from the pumping enable signal control unit, to the second adjacent memory chip. 
     The plurality of memory chips may further include an initial level setting unit suitable for latching the power-up signal to initialize the receiving unit. 
     The pumping enable signal control unit may receive memory chip information, which is activated in any one of the memory chips. 
     The pumping enable signal control unit may include a pumping enable signal generation unit suitable for generating the pumping enable signal by controlling the power-up signal or the trigger signal in response to the memory chip information; and a delay unit suitable for delaying the pumping enable signal by the given time and outputting the delayed pumping enable signal to the second adjacent memory chip. 
     The pumping enable signal generation unit may generate the pumping enable signal in response to the power-up signal when the memory chip information is activated, and generate the pumping enable signal in response to the trigger signal when the memory chip information is deactivated. 
     Each of the memory chips may further include a power-up signal generation unit suitable for generating the power-up signal by detecting an external voltage. 
     In an embodiment, there is provided a semiconductor integrated circuit including a plurality of memory chips stacked therein. Each of the memory chips may include: a pumping enable signal generation unit suitable for generating a pumping enable signal in response to a power-up signal in a first memory chip of the memory chips, or generating the pumping enable signal in response to a trigger signal transmitted from a first adjacent memory chip in the memory chips other than the first memory chip; a delay unit suitable for delaying the pumping enable signal by a given time and outputting the delayed pumping enable signal to a second adjacent memory chip; and a pumping unit suitable for generating a pumping voltage by performing a pumping operation in response to the pumping enable signal. 
     Each of the memory chips may further include a receiving unit suitable for receiving the trigger signal and outputting the received trigger signal to the pumping enable signal generation unit; and a transmitting unit suitable for transmitting the delayed pumping enable signal outputted from the delay unit to the second adjacent memory chip. 
     The plurality of memory chips may further include an initial level setting unit suitable for latching the power-up signal to initialize the receiving unit. 
     The pumping enable signal generation unit may receive memory chip information, which is activated in any one of the memory chips. 
     The pumping enable signal generation unit may generate the pumping enable signal in response to the power-up signal when the memory chip information is activated, and generates the pumping enable signal in response to the trigger signal when the memory chip information is deactivated. 
     Each of the memory chips may further comprise a power-up signal generation unit suitable for generating the power signal by detecting an external voltage. 
     In an embodiment, there is provided a method of driving a semiconductor integrated circuit that includes a plurality of memory chips stacked therein. The method may include: generating a pumping enable signal in response to a power-up signal of the lowermost memory chip among the plurality of memory chips; performing a pumping operation in response to the pumping enable signal, and delaying the pumping enable signal by a given time; and performing a pumping operation of the next memory chip in response to the delayed pumping enable signal, and delaying the delayed pumping enable signal by the given time, wherein the pumping operations are sequentially performed from the lowermost memory chip to the uppermost memory chip, in response to the delayed pumping enable signal. 
     While the pumping operation may be perform in a selected memory chip among the memory chips, the other memory chips excluding the selected memory chip do not perform the pumping operation. 
     In an embodiment, there is provided a method of driving a semiconductor integrated circuit that includes a plurality of memory chips stacked therein. The method may include: generating a pumping enable signal in response to a power-up signal of a first memory chip among the plurality of memory chips; performing a pumping operation of the first memory chip in response to the pumping enable signal, and delaying the pumping enable signal by a given time to output the delayed pumping enable signal to a second memory chip adjacent to the first memory chip; performing a pumping operation of the second memory chip in response to the delayed pumping enable signal, and delaying the delayed pumping enable signal by the given time to output the delayed pumping enable signal to a third memory chip adjacent to the second memory chip; and sequentially performing pumping operations from the third memory chip to the last memory chip, in response to the delayed pumping enable signal transmitted from the previous memory chip. 
     The first memory chip may be the lowermost memory chip, and the pumping operations may be sequentially performed from the lowermost memory chip to the uppermost memory chip. 
     The method may further include: generating the power signal by detecting an external voltage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a semiconductor integrated circuit in accordance with an embodiment of the present invention. 
         FIG. 2  is a circuit diagram illustrating a pumping enable signal generation unit of a first memory chip shown in  FIG. 1 . 
         FIG. 3  is a circuit diagram illustrating a delay unit of the first memory chip shown in  FIG. 1 . 
         FIG. 4  is a timing diagram illustrating an operation of the semiconductor integrated circuit of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Throughout the disclosure, like reference numerals refer to like parts throughout the various figures and embodiments of the present invention. 
       FIG. 1  is a block diagram illustrating a semiconductor integrated circuit in accordance with an embodiment of the present invention. 
     Referring to  FIG. 1 , the semiconductor integrated circuit may include first to fourth memory chips SLICE 1  to SLICE 4 . The first to fourth memory chips SLICE 1  to SLICE 4  may be vertically stacked. Between the respective memory chips, first to third TSVs TSV 1  to TSV 3  may be provided to transmit signals. 
     The first memory chip SLICE 1  may include a power-up signal generation unit  110 A, an initial level setting unit  115 A, a receiving unit  120 A, a pumping enable signal control unit  130 A, a pumping unit  140 A, and a transmitting unit  150 A. 
     The power-up signal generation unit  110 A may detect a level of an external voltage received from outside, and generate a power-up signal PWRUP 1  when the level of the external voltage is equal to or greater than a preset target level. The power-up signal generation unit  110 A may output the power-up signal PWRUP 1  to the initial level setting unit  115 A and the pumping enable signal control unit  130 A. 
     The initial level setting unit  115 A may receive and latch the power-up signal PWRUP 1 , to output a latch signal LT_SIG 1  to the receiving unit  120 A. The initial level setting unit  115 A may serve to set an initial level of the latch signal LT_SIG 1  by latching the power-up signal PWRUP 1 .  FIG. 1  illustrates that the initial level setting unit  115 A is provided only in the first memory chip SLICE 1 . However, the initial level setting unit  115 A may also be provided in the second to fourth memory chips SLICE 2  to SLICE 4 , in order to reduce process costs. 
     The receiving unit  120 A may receive the latch signal LT_SIG 1  from the initial level setting unit  115 A and output the latch signal LT_SIG 1  as a first trigger signal TRG 1  to the pumping enable signal control unit  130 A. 
     The pumping enable signal control unit  130 A may generate a first pumping enable signal VPP_EN 1  in response to the power-up signal PWRUP 1 , the first trigger signal TRG 1 , and memory chip information SID_ 1 , and delay the first pumping enable signal VPP_EN 1  by a predetermined time to output a first pumping enable delayed signal DLY_VPP_EN 1  to the second memory chip SLICE 2 . 
     The pumping enable signal control unit  130 A may include a pumping enable signal generation unit  131 A and a delay unit  133 A. 
     The pumping enable signal generation unit  131 A may receive the memory chip information SID_ 1 , the power-up signal PWRUP 1  provided from the power-up signal generation unit  110 A, and the first trigger signal TRG 1  provided from the receiving unit  120 A. The memory chip information SID_ 1  is activated in the first memory chip SLICE 1 , but deactivated in the second to fourth memory chips SLICE 2  to SLICE 4  excluding the first memory chip SLICE 1 . The pumping enable signal generation unit  131 A may generate the first pumping enable signal VPP_EN 1  by controlling the power-up signal PWRUP 1  and the first trigger signal TRG 1  in response to the memory chip information SID_ 1 . Specifically, as the memory chip information SID_ 1  is activated, the pumping enable signal generation unit  131 A may generate the first pumping enable signal VPP_EN 1  in response to the power-up signal PWRUP 1 . Alternatively, as the memory chip information SID_ 1  is deactivated, the pumping enable signal generation unit  131 A may generate the first pumping enable signal VPP_EN 1  in response to the first trigger signal TRG 1 . The pumping enable signal generation unit  131 A may output the first pumping enable signal VPP_EN 1  to the delay unit  133 A and the pumping unit  140 A. 
     The delay unit  133 A may delay the first pumping enable signal VPP_EN 1  by the predetermined time, and generate the first pumping enable delayed signal DLY_VPP_EN 1 . The delay unit  133 A may output the first pumping enable delayed signal DLY_VPP_EN 1  to the transmitting unit  150 A. 
     The pumping unit  140 A may perform a pumping operation in response to the first pumping enable signal VPP_EN 1 . That is, the pumping unit  140 A may generate a pumping voltage higher than the external voltage received from the outside, through the pumping operation. 
     Thus, the predetermined time of the delay unit  133 A may indicate a sufficient time during which the pumping operation may be completed. 
     The transmitting unit  150 A may receive the first pumping enable delayed signal DLY_VPP_EN 1  from the delay unit  133 A, and transmit the received signal to the second memory chip SLICE 2  through the first TSV TSV 1 . 
     The second memory chip SLICE 2  may include a power-up signal generation unit  110 B, an initial level setting unit  115 B, a receiving unit  120 B, a pumping enable signal control unit  130 B, a pumping unit  140 B, and a transmitting unit  150 B. The pumping enable signal control unit  1306  may include a pumping enable signal generation unit  1316  and a delay unit  133 B. 
     The power-up signal generation unit  110 B may detect the level of the external voltage, and generate a power-up signal PWRUP 2  when the level of the external voltage is equal to or greater than a preset target level. The power-up signal generation unit  110 B may output the power-up signal PWRUP 2  to the initial level setting unit  115 B and the pumping enable signal control unit  130 B. 
     The initial level setting unit  115 B may receive and latch the power-up signal PWRUP 2  to output a latch signal LT_SIG 2  to the receiving unit  120 B. The initial level setting unit  115 B may serve to set an initial level of the latch signal LT_SIG 2  by latching the power-up signal PWRUP 2 . 
     The receiving unit  120 B may receive the latch signal LT_SIG 2  from the initial level setting unit  115 B. The receiving unit  120 B may receive the first pumping enable delayed signal DLY_VPP_EN 1  from the transmitting unit  150 A of the first memory chip SLICE 1  through the first TSV TSV 1 . The receiving unit  120 B may set the initial level of a second trigger signal TRG 2  in response to the latch signal LT_SIG 2 . The receiving unit  120 B of the second memory chip SLICE 2  may output the first pumping enable delayed signal DLY_VPP_EN 1  as the second trigger signal TRG 2  to the pumping enable signal generation unit  131 B. 
     The pumping enable signal generation unit  131 B may receive the memory chip information SID_ 1 , the power-up signal PWRUP 2 , and the second trigger signal TRG 2 . As described above, the memory chip information SID_ 1  may be deactivated in the second to fourth memory chips SLICE 2  to SLICE 4  excluding the first memory chip SLICE 1 . The pumping enable signal generation unit  131 B may block the power-up signal PWRUP 2  in response to the deactivated memory chip information SID_ 1 , and output the second trigger signal TRG 2  as a second pumping enable signal VPP_EN 2  to the delay unit  133 B and the pumping unit  140 B. 
     The delay unit  133 B may delay the second pumping enable signal VPP_EN 2  by a predetermined time, and generate a second pumping enable delayed signal DLY_VPP_EN 2 . The delay unit  133 B may output the second pumping enable delayed signal DLY_VPP_EN 2  to the transmitting unit  150 B. 
     The pumping unit  140 B may perform a pumping operation in response to the second pumping enable signal VPP_EN 2 . 
     The transmitting unit  150 B may receive the second pumping enable delayed signal DLY_VPP_EN 2  from the delay unit  133 B, and transmit the received signal to the third memory chip SLICE 3  through the second TSV TSV 2 . 
     The third memory chip SLICE 3  may include a power-up signal generation unit  110 C, an initial level setting unit  115 B, a receiving unit  120 C, a pumping enable signal control unit  130 C, a pumping unit  140 C, and a transmitting unit  150 C, like the second memory chip SLICE 2 . 
     The fourth memory chip SLICE 4  may include a power-up signal generation unit  110 D, an initial level setting unit  115 B, a receiving unit  120 D, a pumping enable signal control unit  130 D, a pumping unit  140 D, and a transmitting unit  150 D, like the second memory chip SLICE 2 . 
     Next, an operation of the semiconductor integrated circuit will be described. 
     When the levels of external voltages in the power-up signal generation units  110 A to  110 D of the first to fourth memory chips SLICE 1  to SLICE 4  become equal to or greater than a predetermined level, the power-up signal generation units  110 A to  110 D may generate power-up signals PWRUP 1 ˜PWRUP 4 , respectively. The memory chip information SID_ 1  may be activated only in the first memory chip SLICE 1 , and deactivated in the second to fourth memory chips SLICE 2  to SLICE 4  excluding the first memory chip SLICE 1 . The initial level setting unit  115 A of the first memory chip SLICE 1  may receive and latch the power-up signal PWRUP 1  generated in the first memory chip SLICE 1 , and output the latch signal LT_SIG 1  to the receiving unit  120 A. The receiving unit  120 A may output the latch signal LT_SIG 1  as the first trigger signal TRG 1  to the pumping enable signal control unit  131 A. The pumping enable signal generation unit  131 A may output the power-up signal PWRUP 1  as the first pumping enable signal VPP_EN 1  in response to the activated memory chip information SID_ 1 . The pumping unit  140 A may perform a pumping operation in response to the first pumping enable signal VPP_EN 1 . The delay unit  133 A may receive the first pumping enable signal VPP_EN 1 , delay the first pumping enable signal VPP_EN 1  by a predetermined time, and output the first pumping enable delayed signal DLY_VPP_EN 1 . The transmitting unit  150 A may transmit the first pumping enable delayed signal DLY_VPP_EN 1  outputted from the delay unit  133 A to the second memory chip SLICE 2  through the first TSV TSV 1 . 
     The initial level setting unit  115 B of the second memory chip SLICE 2  may receive and latch the power-up signal PWRUP 2  generated in the second memory chip SLICE 2 , and output the latch signal LT_SIG 2  to the receiving unit  120 B. The receiving unit  120 B may be initialized in response to the latch signal LT_SIG 2 . The receiving unit  120 B of the second memory chip SLICE 2  may receive the first pumping enable delayed signal DLY_VPP_EN 1  transmitted through the first TSV TSV 1 , and output the second trigger signal TRG 2  to the pumping enable signal generation unit  131 B. The pumping enable signal generation unit  131 B may block the power-up signal PWRUP 2  generated from the power-up signal generation unit  110 B, and output the second trigger signal TRG 2  as the second pumping enable signal VPP_EN 2  in response to the deactivated memory chip information SID_ 1 . The pumping unit  140 B may perform a pumping operation in response to the second pumping enable signal VPP_EN 2 . The delay unit  133 B may receive the second pumping enable signal VPP_EN 2 , delay the received signal by the predetermined time, and output the second pumping enable delayed signal DLY_VPP_EN 2 . The transmitting unit  150 B may transmit the second pumping enable delayed signal DLY_VPP_EN 2  outputted from the delay unit  133 B to the third memory chip SLICE 3  through the second TSV TSV 2 . 
     The initial level setting unit  115 C of the third memory chip SLICE 3  may receive and latch the power-up signal PWRUP 3  generated in the third memory chip SLICE 3 , and output the latch signal LT_SIG 3  to the receiving unit  120 C. The receiving unit  120 C may be initialized in response to the latch signal LT_SIG 3 . The receiving unit  120 C of the third memory chip SLICE 3  may receive the second pumping enable delayed signal DLY_VPP_EN 2  transmitted through the second TSV TSV 2 , and output the third trigger signal TRG 3  to the pumping enable signal generation unit  131 C. The pumping enable signal generation unit  131 C may block the power-up signal PWRUP 3  generated from the power-up signal generation unit  110 C, and output the third trigger signal TRG 3  as the third pumping enable signal VPP_EN 3  in response to the deactivated memory chip information SID_ 1 . The pumping unit  140 C may perform a pumping operation in response to the third pumping enable signal VPP_EN 3 . The delay unit  133 C may receive the third pumping enable signal VPP_EN 3 , delay the third pumping enable signal VPP_EN 3  by the predetermined time, and output the third pumping enable delayed signal DLY_VPP_EN 3 . The transmitting unit  150 C may transmit the third pumping enable delayed signal DLY_VPP_EN 3  outputted from the delay unit  133 B to the fourth memory chip SLICE 4  through the third TSV TSV 3 . 
     The initial level setting unit  115 D of the fourth memory chip SLICE 4  may receive and latch the power-up signal PWRUP 4  generated in the fourth memory chip SLICE 4 , and output the latch signal LT_SIG 4  to the receiving unit  120 D. The receiving unit  120 D may be initialized in response to the latch signal LT_SIG 4 . The receiving unit  120 D of the fourth memory chip SLICE 4  may receive the third pumping enable delayed signal DLY_VPP_EN 3  transmitted through the third TSV TSV 3 , and output the fourth trigger signal TRG 4  to the pumping enable signal generation unit  131 D. The pumping enable signal generation unit  131 D may block the power-up signal PWRUP 4  generated from the power-up signal generation unit  110 D, and output the fourth trigger signal TRG 4  as the fourth pumping enable signal VPP_EN 4  in response to the deactivated memory chip information SID_ 1 . The pumping unit  140 D may perform a pumping operation in response to the fourth pumping enable signal VPP_EN 4 . The delay unit  133 D may receive the fourth pumping enable signal VPP_EN 4 , delay the received signal by the predetermined time, and output the fourth pumping enable delayed signal DLY_VPP_EN 4 . The transmitting unit  150 D may output the fourth pumping enable delayed signal DLY_VPP_EN 4  to an upper memory chip (not illustrated) through the fourth TSV TSV 4 . 
     The semiconductor integrated circuit in accordance with the embodiment of the present invention may generate the first pumping enable signal VPP_EN 1  in response to the power-up signal PWRUP 1  generated in the first memory chip SLICE 1 , and perform a pumping operation in response to the first pumping enable signal VPP_EN 1 . Then, each of the second to fourth memory chips SLICE 2  to SLICE 4  may perform a pumping operation in response to the pumping enable delayed signal transmitted from the lower memory chip, instead of the power-up signal generated therein. Thus, the semiconductor integrated circuit may sequentially perform the pumping operations of the first to fourth memory chips SLICE 1  to SLICE 4 . The semiconductor integrated circuit may distribute the timings at which the pumping operations are performed for the respective memory chips. Accordingly, the semiconductor integrated circuit may reduce the amount of current consumed at once by performing the pumping operations of the memory chips at different times. 
       FIG. 2  is a circuit diagram illustrating the pumping enable signal generation unit  131 A of the first memory chip SLICE 1  shown in  FIG. 1 . 
     Referring to  FIG. 2 , the pumping enable signal generation unit  131 A may include a first NAND gate NAND 1  and a second NAND gate NAND 2 . The first NAND gate NAND 1  may perform a NAND operation on the power-up signal PWRUP 1  and the memory chip information SID_ 1 , and the second NAND gate NAND 2  may perform a NAND operation on the first trigger signal TRG 1  and an inverted signal of the memory chip information SID_ 1 , which is obtained by inverting the memory chip information SID_ 1  through an inverter INV. The pumping enable signal generation unit may include a third NAND gate NAND 3  to perform a NAND operation on output signals of the first and second NAND gates NAND 1  and NAND 2 . 
     When the memory chip information SID_ 1  is activated, the first NAND gate NAND 1  may output a low-level signal in response to the power-up signal PWRUP 1  having a high level. The second NAND gate NAND 2  may output a high-level signal in response to the inverted signal of the memory chip information SID_ 1 , regardless of the first trigger signal TRG 1 . Thus, the third NAND gate NAND 3  may output the first pumping enable signal VPP_EN 1  having a high level. 
     On the other hand, when the memory chip information SID_ 1  is deactivated, the first NAND gate NAND 1  may output a high-level signal regardless of the power-up signal PWRUP 1 . The second NAND gate NAND 2  may output a low-level signal based on the first trigger signal TRG 1  having a high level and the inverted signal of the memory chip information SID_ 1  having a high level. Thus, the third NAND gate NAND 3  may output the first pumping enable signal VPP_EN 1  having a high level. 
       FIG. 2  illustrates the circuit configuration of the pumping enable signal generation unit  131 A provided in the first memory chip SLICE 1 . However, the pumping enable signal generation units  131 B to  131 D provided in the second to fourth memory chips SLICE 2  to SLICE 4  may be configured in the same manner as the pumping enable signal generation unit  131 A. Thus, in the first memory chip SLICE 1 , the pumping enable signal generation unit  131 A may output the first pumping enable signal VPP_EN 1  based on the power-up signal PWRUP 1  in response to the activated memory chip information SID_ 1 . In the second to fourth memory chips SLICE 2  to SLICE 4 , the pumping enable signal generation units  131 B to  131 D may output the pumping enable signals VPP_EN 2  to VPP_EN 4  based on the second to fourth trigger signals TRG 2  to TRG 4  that are transmitted from the respective receiving units  120 B to  120 D in response to the deactivated memory chip information SID_ 1 . 
       FIG. 3  is a circuit diagram illustrating the delay unit  133 A of the first memory chip SLICE 1  shown in  FIG. 1 . 
     Referring to  FIG. 3 , the delay unit  133 A may include an oscillator  310 , a transmission controller  320 , and a counter  330 . 
     The oscillator  310  may receive the first pumping enable signal VPP_EN 1 , and output a periodic pulse signal PPS. 
     The transmission controller  320  may include an inverter and a NAND gate. The inverter may invert the first pumping enable delayed signal DLY_VPP_EN 1 , and the NAND gate may perform a NAND operation on the periodic pulse signal PPS and an output signal of the inverter. During an initial operation of the transmission controller  320 , the first pumping enable delayed signal DLY_VPP_EN 1  may be at a low-level as an initial value. The inverter may invert the first pumping enable delayed signal DLY_VPP_EN 1  to output a high-level signal to the NAND gate. The NAND gate may invert the periodic pulse signal PPS in response to the high-level signal, and output an inverted signal of the periodic pulse signal PPS to the counter  330 . 
     The counter  330  may include eight counters CNT. The counter  330  may delay the inverted signal of the periodic pulse signal PPS outputted from the transmission controller  320  through a counting operation. The counter  330  may output the first pumping enable delayed signal DLY_VPP_EN 1 , which is delayed by the predetermined time while passing through the eight counters CNT. The counter  330  may output the first pumping enable delayed signal DLY_VPP_EN 1  changing it to a high level from the initial value of the low level after the predetermined time from the initial operation. 
     After the predetermined time, the transmission controller  320  may output a signal fixed to a high level regardless of the periodic pulse signal PPS outputted from the oscillator  310 , in response to the first pumping enable delayed signal DLY_VPP_EN 1  having a high level. As the signal outputted from the transmission controller  320  is fixed to a high level, the operation of the counter  330  may be stopped. 
     For reference, the counter  330  may serve to output the first pumping enable delayed signal DLY_VPP_EN 1  by delaying the first pumping enable signal VPP_EN 1  by a time required until each pumping operation of the pumping units  140 A to  140 D is completed, and the number of counters CNT may be adjusted as a design option.  FIG. 3  illustrates the circuit configuration of the delay unit  133 A provided in the first memory chip SLICE 1 . However, the delay units  1338  to  133 D provided in the second to fourth memory chips SLICE 2  to SLICE 4  may be configured in the same manner as the delay unit  133 A. 
       FIG. 4  is a timing diagram illustrating an operation of the semiconductor integrated circuit of  FIG. 1 . In  FIG. 4 , it is assumed that each of the delay units  133 A to  133 D may have a delay time T 1 . 
     Referring to  FIGS. 1 to 4 , the first memory chip SLICE 1  may activate the first pumping enable signal VPP_EN 1  in response to the power-up signal PWRUP 1 . The pumping unit  140 A of the first memory chip SLICE 1  may perform the pumping operation in response to the first pumping enable signal VPP_EN 1 . The delay unit  133 A may generate the first pumping enable delayed signal DLY_VPP_EN 1  by delaying the first pumping enable signal VPP_EN 1  by the delay time T 1 . 
     The second memory chip SLICE 2  may receive the first pumping enable delayed signal DLY_VPP_EN 1 , and activate the second pumping enable signal VPP_EN 2  in response to the second trigger signal TRG 2  generated based on the first pumping enable delayed signal DLY_VPP_EN 1 . The pumping unit  140 B of the second memory chip SLICE 2  may perform the pumping operation in response to the second pumping enable signal VPP_EN 2 . The delay unit  133 B may generate the second pumping enable delayed signal DLY_VPP_EN 2  by delaying the second pumping enable signal VPP_EN 2  by the delay time T 1 . 
     The third memory chip SLICE 3  may receive the second pumping enable delayed signal DLY_VPP_EN 2 , and activate the third pumping enable signal VPP_EN 3  in response to the third trigger signal TRG 3  generated based on the second pumping enable delayed signal DLY_VPP_EN 2 . The pumping unit  133 C of the third memory chip SLICE 3  may be perform the pumping operation in response to the third pumping enable signal VPP_EN 3 . The delay unit  133 C may generate the third pumping enable delayed signal DLY_VPP_EN 3  by delaying the third pumping enable signal VPP_EN 3  by the delay time T 1 . As a result, the first pumping enable signal VPP_EN 1  and the third pumping enable signal VPP_EN 3  may have a time difference T 2  equal to twice the delay time T 1 . 
     The fourth memory chip SLICE 4  may receive the third pumping enable delayed signal DLY_VPP_EN 3 , and activate the fourth pumping enable signal VPP_EN 4  in response to the fourth trigger signal TRG 4  generated based on the third pumping enable delayed signal DLY_VPP_EN 3 . The pumping unit  133 D of the fourth memory chip SLICE 4  may perform the pumping operation in response to the fourth pumping enable signal VPP_EN 4 . The delay unit  133 D may generate the fourth pumping enable delayed signal DLY_VPP_EN 4  by delaying the fourth pumping enable signal VPP_EN 4  by the delay time T 1 . As a result, the first pumping enable signal VPP_EN 1  and the fourth pumping enable signal VPP_EN 4  may have a time difference T 3  equal to triple of the time T 1 . 
     Thus, as the activation timings of the pumping enable signals of the first to fourth memory chips in the semiconductor integrated circuit are distributed, the pumping operations may be sequentially performed. 
     The semiconductor integrated circuit in accordance with this embodiment of the present invention may delay a pumping enable signal of a lower memory chip, transmit the delayed pumping enable signal to an upper memory chip, and perform a pumping operation based on the delayed pumping enable signal. Thus, since the semiconductor integrated circuit distributes timings at which pumping operations are performed for the respective memory chips, the semiconductor integrated circuit can reduce the amount of current which is consumed at the same time. 
     In accordance with the embodiments of the present invention, since pumping operations of a plurality of memory chips are performed at different times, it is possible to reduce the amount of current that is consumed at once. 
     Although various embodiments have been described for illustrative purposes, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. 
     For example, the positions and types of logic gates and transistors included in the above-described embodiments may be implemented in different manners depending on the polarity of input signals.