Patent Description:
In a constant on-time voltage regulator, such as a Buck DC-DC converter, a Boost DC-DC converter, or a Buck-Boost DC-DC converter, a part of the output current of the DC-DC converter can be fed back to form a regulation loop. However, a propagation delay within the constant on-time voltage regulator can negatively impact the stability of the regulation loop of the constant on-time based DC-DC converter. For example, when the input voltage and the output voltage of the constant on-time voltage regulator are close to each other, the propagation delay within the constant on-time voltage regulator can cause sub-harmonic oscillation, which decreases the stability of the regulation loop of the constant on-time voltage regulator.

<CIT> discloses a comparator that compares a first input voltage and a second input voltage to generate a comparative output depending on a result of the comparison.

<CIT> discloses a waveform generation circuit that includes: a waveform generation block configured to generate a waveform signal corresponding to a driving control signal; and a control signal generation block configured to generate a driving control signal for compensating the waveform signal for an environmental factor reflected into the waveform generation circuit.

<CIT> discloses a relaxation oscillator circuit with reduced sensitivity of oscillation frequency to comparator delay variation.

<CIT> discloses a constant on-time pulse width control-based apparatus used in a voltage converter, which includes a comparator, a logic circuit, and a controller.

<CIT> discloses a frequency generator comprising a capacitor, a comparing unit, a charging and discharging unit, a delay unit and a charging and discharging switch unit.

According to an aspect of the invention, there is provided the ripple generation device of claim <NUM>.

Embodiments of ripple generation devices for a constant on-time voltage regulator and methods for ripple generation for a constant on-time voltage regulator are described. In an embodiment, a ripple generation device for a constant on-time voltage regulator includes a ripple generator configured to generate a ripple signal, a detector operably connected to the ripple generator and configured to detect a difference between an amplitude of the ripple signal and at least one reference amplitude and a feedback controller operably connected to the ripple generator and the detector and configured to generate a control signal for controlling the amplitude of the ripple signal based on the detected difference. Other embodiments are also described.

In an embodiment, the ripple generator includes an adjustable current source.

In an embodiment, the feedback controller is further configured to control a current value of the adjustable current source based on the detected difference.

In an embodiment, the ripple generator includes an adjustable capacitor.

In an embodiment, the feedback controller is further configured to control a capacitance of the adjustable capacitor based on the detected difference.

In an embodiment, the ripple generator includes an adjustable amplifier.

In an embodiment, the feedback controller is further configured to control a gain of the adjustable amplifier based on the detected difference.

In an embodiment, the ripple generator includes a Continuous Conduction Mode (CCM) ripple generator.

In an embodiment, the ripple generator includes a Discontinuous Conduction Mode (DCM) ripple generator.

In an embodiment, the feedback controller includes a counter.

In an embodiment, the feedback controller is configured to generate the control signal for controlling the amplitude of the ripple signal to be constant.

In an embodiment, the detector includes a plurality of voltage sources, a plurality of comparators operably connected to the voltage sources and to the feedback controller, an XOR gate operably connected to the comparators, and an AND gate operably connected to the XOR gate and the feedback controller.

In an embodiment, the voltage sources includes a first voltage source operably connected to a bias voltage, a second voltage source operably connected to a first comparator of the comparators and to the first voltage source, and a third voltage source operably connected to a second comparator of the comparators and to the first voltage source.

In an embodiment, the first voltage source has an adjustable voltage.

In an embodiment, an output of the first comparator is operably connected to a first input of the XOR gate and to a control terminal of the feedback controller.

In an embodiment, an output of the second comparator is operably connected to a second input of the XOR gate.

In an embodiment, a clock signal is applied to an input of the AND gate, and wherein an output of the AND gate is operably connected a clock terminal of the feedback controller.

In an embodiment, a constant on-time voltage regulator includes a power stage configured to convert an input direct current (DC) voltage into an output DC voltage, a driver device configured to drive the power stage, a timer configured to generate a constant on-time for the drive device, a ripple generation device configured to generate a ripple signal, and a comparator configured to perform voltage comparison in response to the ripple signal to generate an output to the timer. The ripple generation device includes a ripple generator configured to generate the ripple signal, a detector operably connected to the ripple generator and configured to detect a difference between an amplitude of the ripple signal and at least one reference amplitude and a feedback controller operably connected to the ripple generator and the detector and configured to generate a control signal for controlling the amplitude of the ripple signal based on the detected difference.

In an embodiment, the ripple generator includes at least one of an adjustable current source, an adjustable capacitor and an adjustable amplifier, and wherein the feedback controller is further configured to control at least one of a current value of the adjustable current source, a capacitance of the adjustable capacitor and a gain of the adjustable amplifier based on the detected difference.

In an embodiment, a method for ripple generation for a constant on-time voltage regulator involves generating a ripple signal, detecting a difference between an amplitude of the ripple signal and at least one reference amplitude and generating a control signal for controlling the amplitude of the ripple signal based on the detected difference.

Other aspects and advantages of embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, depicted by way of example of the principles of the invention.

Thus, the following detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the present disclosure, but is merely representative of various embodiments.

The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by this detailed description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment.

Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment. Thus, the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

<FIG> is a schematic block diagram of a ripple generation device <NUM> in accordance with an embodiment of the invention. In the embodiment depicted in <FIG>, the ripple generation device includes a ripple generator <NUM>, a detector <NUM> and a feedback controller <NUM>. The detector and the feedback controller form a feedback control loop. The ripple generation device can be used to provide ripple signals for a constant on-time voltage regulator, which may be, for example, a Buck constant on-time voltage regulator in which the input voltage is higher than the output voltage, a Boost constant on-time voltage regulator in which the input voltage is lower than the output voltage, or a Buck-Boost constant on-time voltage regulator in which the input voltage is higher or lower than the output voltage. In a constant on-time voltage regulator, an active and inactive cycle is provided depending on the input voltage such that a defined on and off time is generated. In some embodiments, a timing signal with a constant on time (i.e., the time duration of an active portion of the waveform of the timing signal being constant) is generated in a constant on-time voltage regulator. Although the ripple generation device is shown in <FIG> as including certain components, in some embodiments, the ripple generation device includes less or more components to implement less or more functionalities.

The ripple generation device <NUM> depicted in <FIG> can use feedback control to regulate ripple signal amplitude. For example, the ripple generation device can use feedback control to regulate ripple signal amplitude in order to achieve the constant ripple amplitude regardless of the change of other parameters in a constant on-time voltage regulator. When the input voltage and the output voltage of a constant on-time voltage regulator are close to each other, the ripple generation device can use feedback control to regulate ripple signal amplitude in order to achieve the constant ripple amplitude, which keeps the propagation delay within the constant on-time voltage regulator within a tolerance threshold. For example, when the ripple amplitude decreases, the ripple generation device can compensate for the decrease in ripple amplitude. Consequently, sub-harmonic oscillation caused by the propagation delay can be reduced or eliminated, and the stability of the regulation loop of the constant on-time voltage regulator can be maintained.

The ripple generator <NUM> of the ripple generation device <NUM> is configured to generate a ripple signal. In some embodiments, the ripple signal is a voltage signal having a triangular waveform or other suitable waveform. In some embodiments, the ripple signal is added or subtracted from another signal, which may be a DC signal (e.g., an output voltage, VOUT, of a voltage regulator in which the ripple generation device <NUM> is included or another DC signal). The ripple generator may be implemented using one or more analog circuits and/or one or more digital circuits.

The detector <NUM> of the ripple generation device <NUM> is operably connected to the ripple generator <NUM> and is configured to detect a difference between an amplitude of the ripple signal and at least one reference amplitude. In some embodiments, the detector is implemented using one or more analog circuits and/or one or more digital circuits.

The feedback controller <NUM> of the ripple generation device <NUM> is operably connected to the ripple generator <NUM> and the detector <NUM> and is configured to generate a control signal for controlling the amplitude of the ripple signal based on the detected difference. The feedback controller is implemented using one or more analog circuits and/or one or more digital circuits. In some embodiments, the feedback controller is implemented using a processor such as a microcontroller or a central processing unit (CPU).

<FIG> depicts an embodiment of the ripple generation device <NUM> of <FIG>. In the embodiment depicted in <FIG>, a ripple generation device <NUM> includes a ripple generator <NUM>, a detector <NUM> and an up/down counter <NUM>. The ripple generator, the detector and the feedback controller form a feedback control loop. The ripple generation device can be used to provide ripple signals for a constant on-time voltage regulator. The ripple generation device <NUM> depicted in <FIG> is one possible embodiment of the ripple generation device <NUM> depicted in <FIG>. Specially, the ripple generator <NUM>, the detector <NUM> and the up/down counter <NUM> are embodiments of the ripple generator <NUM>, the detector <NUM> and the feedback controller <NUM> depicted in <FIG>, respectively. However, the ripple generation device depicted in <FIG> is not limited to the embodiment shown in <FIG>.

The ripple generator <NUM> of the ripple generation device <NUM> is configured to generate a ripple signal. In the embodiment depicted in <FIG>, a voltage, "Vbias," is applied to the ripple generator and to the detector <NUM>. The voltage, Vbias, is an output voltage of a constant on-time voltage regulator into which the ripple generation device <NUM> is included or other DC voltage. In some embodiments, the ripple generator is implemented using one or more analog circuits and/or one or more digital circuits.

The detector <NUM> of the ripple generation device <NUM> is operably connected to the ripple generator <NUM> and is configured to detect a difference between an amplitude of the ripple signal and at least one reference amplitude. In the embodiment depicted in <FIG>, the detector includes a first voltage source <NUM> having a voltage, "Vamp," a second voltage source <NUM> having a voltage, "Vwn," a third voltage source <NUM> having a voltage, "Vwp," a first comparator <NUM>, a second comparator <NUM>, an XOR gate <NUM> and an AND gate <NUM>. The first voltage source <NUM> is connected between the second voltage source <NUM> and the third voltage source <NUM>. The second voltage source <NUM> is connected to the first comparator and the third voltage source <NUM> is connected to the second comparator. The first and second comparators are connected to inputs of the XOR gate. An output of the XOR gate and a clock signal, "clk," are connected to inputs of the AND gate.

The up/down counter <NUM> of the ripple generation device <NUM> is operably connected to the ripple generator <NUM> and the detector <NUM> and is configured to generate a control signal for controlling the amplitude of the ripple signal based on the detected difference. In the embodiment depicted in <FIG>, the up/down counter includes a clock terminal <NUM> and an up/down control terminal <NUM>. The up/down counter is implemented using one or more analog circuits and/or one or more digital circuits. In some embodiments, the up/down counter is implemented using a processor such as a microcontroller or a CPU. In the embodiment depicted in <FIG>, the output of the AND gate <NUM> is input into the clock terminal of the up/down counter. In addition, an output signal, "cmp_n," of the first comparator is connected to the up/down control terminal of the up/down counter.

In an exemplary operation of the ripple generation device <NUM>, when a ripple signal from the ripple generator reaches its peak value, the detector <NUM> compares the peak value with two reference voltages, vbias+Vamp+Vwp, and, vbias+Vamp-Vwn. If the peak value of the ripple signal is larger than vbias+Vamp+Vwp, the output signal, "cmp_p," of the second comparator <NUM>, is at logic high (e.g., logic <NUM>) while the output signal, cmp_n, of the first comparator <NUM> is at logic low (e.g., logic <NUM>). Consequently, the output signal, "cmp_xor," of the XOR gate <NUM> is at logic high (e.g., logic <NUM>). Because the output signal, cmp_xor, of the XOR gate is at logic high, the output signal of the AND gate <NUM> is the clock signal, clk, which is then input into the clock terminal <NUM> of the up/down counter <NUM>. Because the output signal, cmp_n, of the first comparator is at logic low, the counter value of the up/down counter decreases and the up/down counter instructs the ripple generator to reduce the ripple amplitude. If the peak value of the ripple signal is smaller than vbias+Vamp-Vwn, the output signal, cmp_n, of the first comparator <NUM> is at high while the output signal, cmp_p, of the second comparator <NUM> is at logic low. Consequently, the output signal, cmp_xor, of the XOR gate <NUM> is at logic high (e.g., logic <NUM>). Because the output signal, cmp_xor, of the XOR gate is at logic high, the output signal of the AND gate <NUM> is the clock signal, clk, which is then input into the clock terminal <NUM> of the up/down counter <NUM>. Because the output signal, cmp_n, of the first comparator is at logic low, the counter value of the up/down counter increases and the up/down counter instructs the ripple generator to increase the ripple amplitude. If the peak value of the ripple signal is between vbias+Vamp-Vwn and vbias+Vamp+Vwp, the output signal, cmp_p, of the second comparator <NUM> is at logic low while the output signal, cmp_n, of the first comparator <NUM> is also at logic low. Consequently, the output signal, cmp_xor, of the XOR gate <NUM> is at logic low. Because the output signal, cmp_xor, of the XOR gate is at logic low, the output signal of the AND gate <NUM> is at logic low, which is then input into the clock terminal <NUM> of the up/down counter <NUM>. Consequently, the up/down counter keeps its output counter value not changed and the ripple generator maintains the ripple signal amplitude. Because the valley value of the ripple signal is vbias, the amplitude of the ripple signal (delta between peak and valley) can be regulated to the value between Vamp-Vwn and Vamp+Vwp.

In some embodiments, the ripple generation device <NUM> of <FIG> is a Continuous Conduction Mode (CCM) ripple generation device that produces a continuous ripple waveform. <FIG> depicts an embodiment of the ripple generation device <NUM> of <FIG> with a Continuous Conduction Mode (CCM) ripple generator <NUM> having adjustable current sources <NUM>, <NUM>. In the embodiment depicted in <FIG>, a ripple generation device <NUM> includes the ripple generator <NUM>, the detector <NUM> and the up/down counter <NUM>. The detector and the feedback controller form a feedback control loop. The ripple generation device can be used to provide ripple signals for a constant on-time voltage regulator. In the embodiment depicted in <FIG>, a voltage, Vbias, is applied to the ripple generator and to the detector. The voltage, Vbias, is an output voltage of a constant on-time voltage regulator into which the ripple generation device is included or other DC voltage. The ripple generation device <NUM> depicted in <FIG> is one possible embodiment of the ripple generation device <NUM> depicted in <FIG>. Specially, the ripple generator <NUM> depicted in <FIG> is an embodiment of the ripple generator <NUM> depicted in <FIG>. However, the ripple generation device depicted in <FIG> is not limited to the embodiment shown in <FIG>.

In the embodiment depicted in <FIG>, the ripple generator <NUM> includes the first current source <NUM> with an adjustable current of "mVIN," (where m is a control factor or coefficient), the second current source <NUM> with an adjustable current of "mVOUT," a first switch <NUM> that is controlled by a Pulse Width Modulation (PWM) signal <NUM> or other control signal, a second switch <NUM> that is controlled by a reset signal <NUM>, and a capacitor, <NUM>. The value of the control factor or coefficient, m, is controlled by the up/down counter <NUM>. The control factor or coefficient, m, may be linear or non-linear with respect to the output of the up/down counter and/or the control signal at the up/down control terminal <NUM>. The ripple generator is configured to generate a ripple voltage signal, "Vripple. " In the embodiment depicted in <FIG>, the ripple voltage signal, Vripple, and a reference voltage, "Vc," are applied to inputs of a comparator <NUM> of a constant on-time voltage regulator in which the ripple generator is included. The output of the comparator is connected to a constant on timer <NUM> of the constant on-time voltage regulator. The constant on timer may be implemented by any type of on timer that can generate a timing signal with an active portion having fixed time duration. In some embodiments, the constant on timer is implemented using at least one processor such as a microcontroller or a CPU.

In an exemplary operation of the ripple generation device <NUM>, the detector <NUM> compares the ripple voltage signal, Vripple, with two reference voltages, vbias+Vamp+Vwp, and, vbias+Vamp-Vwn. Depending on the relationships between the ripple voltage signal, Vripple, with the two reference voltages, vbias+Vamp+Vwp, and, vbias+Vamp-Vwn, the outputs of the first and second comparators <NUM>, <NUM>, the XOR gate <NUM> and the AND gate <NUM> are set and the up/down counter <NUM> is controlled, similarly or identical to the operation of the ripple generation device <NUM> described with reference to <FIG>. When the counter value of the up/down counter decreases and the up/down counter instructs the ripple generator to reduce the ripple amplitude, the value of m for the first and second current sources <NUM>, <NUM> with the adjustable currents of mVIN, mVOUT, is reduced. When the counter value of the up/down counter increases and he up/down counter instructs the ripple generator to increase the ripple amplitude, the value of m for the first and second current sources <NUM>, <NUM> with the adjustable currents of mVIN, mVOUT, is increased. When the up/down counter keeps its output counter value not changed and the ripple generator maintains the ripple signal amplitude, the value of m for the first and second current sources <NUM>, <NUM> with the adjustable currents of mVIN, mVOUT, is maintained at its current value.

<FIG> is a signal timing diagram corresponding to the CCM ripple generation device <NUM> depicted in <FIG>. Signals illustrated in <FIG> include the PWM signal <NUM> for the first switch <NUM>, the ripple voltage signal, Vripple, and the reset signal <NUM> for the second switch <NUM>. Circuit mismatch in a previous charging/discharging cycle may cause some residue voltage at the capacitor <NUM>. The reset signal <NUM> can be used to ensure that each time when the charging of the capacitor <NUM> starts, the capacitor <NUM> is discharged first by, for example, shorting top and bottom plates of the capacitor <NUM>, in order to allow that the capacitor voltage starts from zero. At time point, t0, on a rising edge of the PWM signal and a falling edge of the reset signal, the ripple voltage signal, Vripple, begins to increase. At time point, t1, on a falling edge of the PWM signal, the ripple voltage signal, Vripple, reaches its peak. At time point, t2, on a rising edge of the PWM signal and a falling edge of the reset signal, the ripple voltage signal, Vripple, reaches its dip. At time point, t3, on a falling edge of the PWM signal, the ripple voltage signal, Vripple, reaches its peak.

<FIG> depicts an embodiment of the ripple generation device <NUM> of <FIG> with a CCM ripple generator <NUM> with an adjustable capacitor <NUM>. In the embodiment depicted in <FIG>, a ripple generation device <NUM> includes the ripple generator <NUM>, the detector <NUM> and the up/down counter <NUM>. The detector and the feedback controller form a feedback control loop. The ripple generation device can be used to provide ripple signals for a constant on-time voltage regulator. In the embodiment depicted in <FIG>, a voltage, Vbias, is applied to the ripple generator and to the detector. The voltage, Vbias, is an output voltage of a constant on-time voltage regulator into which the ripple generation device is included or other DC voltage. The ripple generation device <NUM> depicted in <FIG> is one possible embodiment of the ripple generation device <NUM> depicted in <FIG>. Specially, the ripple generator <NUM> depicted in <FIG> is an embodiment of the ripple generator <NUM> depicted in <FIG>. However, the ripple generation device depicted in <FIG> is not limited to the embodiment shown in <FIG>.

In the embodiment depicted in <FIG>, the ripple generator <NUM> includes a first current source <NUM> with a current of mVIN, (where m is a control factor or coefficient), a second current source <NUM> with a current of mVOUT, the first switch <NUM> that is controlled by the PWM signal <NUM> or other control signal, the second switch <NUM> that is controlled by the reset signal <NUM>, and a capacitor <NUM> with adjustable capacitance. The capacitor may include multiple capacitance sections, such as capacitor banks, that can be activated or deactivated to increase or decrease its capacitance by the up/down counter <NUM>. The value of the control factor or coefficient, m, is controlled by the up/down counter <NUM>. The control factor or coefficient, m, may be linear or non-linear with respect to the output of the up/down counter and/or the control signal at the up/down control terminal <NUM>. The ripple generator is configured to generate a ripple voltage signal, Vripple. In the embodiment depicted in <FIG>, the ripple voltage signal, Vripple, and a reference voltage, Vc, are applied to inputs of the comparator <NUM> of a constant on-time voltage regulator in which the ripple generator is included. The output of the comparator is connected to the constant on timer <NUM> of the constant on-time voltage regulator.

In an exemplary operation of the ripple generation device <NUM>, the detector <NUM> compares the ripple voltage signal, Vripple, with two reference voltages, vbias+Vamp+Vwp, and, vbias+Vamp-Vwn. Depending on the relationships between the ripple voltage signal, Vripple, with the two reference voltages, vbias+Vamp+Vwp, and, vbias+Vamp-Vwn, the outputs of the first and second comparators <NUM>, <NUM>, the XOR gate <NUM> and the AND gate <NUM> are set and the up/down counter <NUM> is controlled, similarly or identical to the operation of the ripple generation device <NUM> described with reference to <FIG>. When the counter value of the up/down counter decreases and the up/down counter instructs the ripple generator to reduce the ripple amplitude, the capacitance of the capacitor <NUM> is reduced. When the counter value of the up/down counter increases and he up/down counter instructs the ripple generator to increase the ripple amplitude, the capacitance of the capacitor is increased. When the up/down counter keeps its output counter value not changed and the ripple generator maintains the ripple signal amplitude, the capacitance of the capacitor is maintained at its current capacitance value.

In some embodiments, the ripple generation device <NUM> of <FIG> is a Discontinuous Conduction Mode (DCM) ripple generation device that produces a discontinuous ripple waveform. <FIG> depicts an embodiment of the ripple generation device <NUM> of <FIG> with a DCM ripple generator <NUM> having adjustable current sources <NUM>, <NUM>. In the embodiment depicted in <FIG>, a ripple generation device <NUM> includes the ripple generator <NUM>, the detector <NUM> and the up/down counter <NUM>. The detector and the feedback controller form a feedback control loop. The ripple generation device can be used to provide ripple signals for a constant on-time voltage regulator. In the embodiment depicted in <FIG>, a voltage, Vbias, is applied to the ripple generator and to the detector. The voltage, Vbias, is an output voltage of a constant on-time voltage regulator into which the ripple generation device is included or other DC voltage. The ripple generation device <NUM> depicted in <FIG> is one possible embodiment of the ripple generation device <NUM> depicted in <FIG>. Specially, the ripple generator <NUM> depicted in <FIG> is an embodiment of the ripple generator <NUM> depicted in <FIG>. However, the ripple generation device depicted in <FIG> is not limited to the embodiment shown in <FIG>.

In the embodiment depicted in <FIG>, the ripple generator <NUM> includes the first current source <NUM> with an adjustable current of "mVIN," (where m is a control factor or coefficient), the second current source <NUM> with an adjustable current of "mVOUT," a high-side switch <NUM>-<NUM> that is controlled by a control signal <NUM>-<NUM> (e.g., a PWM signal), a low-side switch <NUM>-<NUM> that is controlled by a control signal <NUM>-<NUM> (e.g., a PWM signal), a second switch <NUM> that is controlled by a reset signal <NUM>, and a capacitor, <NUM>. The value of the control factor or coefficient, m, is controlled by the up/down counter <NUM>. The control factor or coefficient, m, may be linear or non-linear with respect to the output of the up/down counter and/or the control signal at the up/down control terminal <NUM>. The ripple generator is configured to generate a ripple voltage signal, Vripple. In the embodiment depicted in <FIG>, the ripple voltage signal, Vripple, and a reference voltage, Vc, are applied to inputs of a comparator <NUM> of a constant on-time voltage regulator in which the ripple generator is included. The output of the comparator is connected to a constant on timer <NUM> of the constant on-time voltage regulator. The constant on timer may be implemented by any type of on timer that can generate a timing signal with an active portion having fixed time duration. In some embodiments, the constant on timer is implemented using at least one processor such as a microcontroller or a CPU.

<FIG> is a signal timing diagram corresponding to the DCM ripple generation device <NUM> depicted in <FIG>. Signals illustrated in <FIG> include the PWM signal <NUM>-<NUM> for the switch <NUM>-<NUM>, the PWM signal <NUM>-<NUM> for the switch <NUM>-<NUM>, the ripple voltage signal, Vripple, and the reset signal <NUM> for the second switch <NUM>. At time point, <NUM>, on a rising edge of the PWM signal <NUM>-<NUM> and a falling edge of the reset signal, the ripple voltage signal, Vripple, begins to increase. At time point, t1, on a falling edge of the PWM signal <NUM>-<NUM> and a rising edge of the PWM signal <NUM>-<NUM>, the ripple voltage signal, Vripple, reaches its peak. At time point, t2, on a falling edge of the PWM signal <NUM>-<NUM> and a rising edge of the reset signal, the ripple voltage signal, Vripple, reaches its dip. At time point, t3, on a rising edge of the PWM signal <NUM>-<NUM> and a falling edge of the reset signal, the ripple voltage signal, Vripple, begins to increase again. At time point, t4, on a falling edge of the PWM signal <NUM>-<NUM> and a rising edge of the PWM signal <NUM>-<NUM>, the ripple voltage signal, Vripple, reaches its peak. At time point, t5, on a falling edge of the PWM signal <NUM>-<NUM> and a rising edge of the reset signal, the ripple voltage signal, Vripple, reaches its dip.

In some embodiments, the ripple generation device <NUM> of <FIG> generates ripple signals based on inductor DC resistance (DCR) current sensing. <FIG> depicts an embodiment of the ripple generation device <NUM> of <FIG> with a ripple generator <NUM> with an amplifier <NUM> with an adjustable gain for DCR current sensing. In the embodiment depicted in <FIG>, a ripple generation device <NUM> includes the ripple generator <NUM>, the detector <NUM> and the up/down counter <NUM>. The ripple generator <NUM> includes the amplifier <NUM> with an adjustable gain, a resistor, Rs, a capacitor Cs, and a resistor, DCR. The resistor, Rs, the capacitor Cs, and the resistor, DCR, may be connected to an inductor and a power stage of a constant on-time voltage regulator into which the ripple generation device <NUM> is included. The ripple generator is configured to generate a ripple voltage signal, Vripple. The ripple generator, the detector and the feedback controller form a feedback control loop. The ripple generation device can be used to provide ripple signals for a constant on-time voltage regulator. In the embodiment depicted in <FIG>, a voltage, Vbias, is applied to the ripple generator and to the detector. The voltage, Vbias, is an output voltage of a constant on-time voltage regulator into which the ripple generation device <NUM> is included or other DC voltage. The ripple generation device <NUM> depicted in <FIG> is one possible embodiment of the ripple generation device <NUM> depicted in <FIG>. Specially, the ripple generator <NUM> depicted in <FIG> is an embodiment of the ripple generator <NUM> depicted in <FIG>. However, the ripple generation device depicted in <FIG> is not limited to the embodiment shown in <FIG>.

<FIG> depicts another embodiment of the ripple generation device <NUM> of <FIG>. In the embodiment depicted in <FIG>, a ripple generation device <NUM> includes the ripple generator <NUM>, a detector <NUM> and the up/down counter <NUM>. The detector and the feedback controller form a feedback control loop. The ripple generation device can be used to provide ripple signals for a constant on-time voltage regulator. The ripple generation device <NUM> depicted in <FIG> is one possible embodiment of the ripple generation device <NUM> depicted in <FIG>. However, the ripple generation device depicted in <FIG> is not limited to the embodiment shown in <FIG>. A difference between the ripple generation device <NUM> depicted in <FIG> and the ripple generation device <NUM> depicted in <FIG> is that the detector <NUM> depicted in <FIG> includes an adjustable voltage source <NUM> having an adjustable voltage, Vamp. Specifically, in the embodiment depicted in <FIG>, the detector includes the adjustable voltage source <NUM> having an adjustable voltage, Vamp, the second voltage source <NUM> having a voltage, Vwn, the third voltage source <NUM> having a voltage, Vwp, the first comparator <NUM>, the second comparator <NUM>, the XOR gate <NUM> and the AND gate <NUM>. The voltage value of Vamp can be changed according to different input and output voltage combinations of a constant on-time voltage regulator in which the ripple generation device is included. In some embodiments, the voltage value of Vamp is changed by feed-forward control (e.g., from an input voltage and/or an output voltage of a constant on-time voltage regulator in which the ripple generation device is included).

<FIG> depicts an embodiment of a Boost constant on-time voltage regulator <NUM> in which the ripple generation device <NUM> of <FIG> can be used. In the embodiment depicted in <FIG>, the Boost constant on-time voltage regulator includes the ripple generation device <NUM>, a constant on timer <NUM>, a comparator <NUM>, a power stage circuit <NUM> that includes power field-effect transistors (FETs) <NUM>, <NUM>, a driver device <NUM>, an inductor <NUM>, a voltage summation device <NUM>, and an optional RC network <NUM>, which includes a capacitor <NUM> and resistors RC, RL. The RC network can be used as a load for the boost constant on-time voltage regulator. In some embodiments, the RC network is not a component of the boost constant on-time voltage regulator. The ripple generation device <NUM>, the comparator and the constant on timer form a feedback control loop. The driver device is a common voltage regulator component, and consequently is not described in detail herein. In some embodiments, the driver device is implemented using at least one processor such as a microcontroller or a CPU. The constant on timer is a common voltage regulator component, and consequently is not described in detail herein. The constant on timer may be implemented by any type of on timer that can generate a timing signal having an active portion with fixed time duration. In some embodiments, the constant on timer is implemented using at least one processor such as a microcontroller or a CPU. The boost constant on-time voltage regulator converts an input voltage, VIN, into an output voltage, VOUT, which is higher than the input voltage, VIN. Although the Boost constant on-time voltage regulator is shown in <FIG> as including certain components, in some embodiments, the Boost constant on-time voltage regulator includes less or more components to implement less or more functionalities.

In the embodiment depicted in <FIG>, the ripple generation device <NUM> is configured to generate a ripple signal for the boost constant on-time voltage regulator <NUM>. The voltage summation device <NUM> is configured to sum up the voltage of the ripple signal that is generated by the ripple generation device with the output voltage, VOUT, of the boost constant on-time voltage regulator. The comparator <NUM> is configured to compare the result from the voltage summation device with a reference voltage, Vref. The constant on timer <NUM> is configured to provide an active and inactive cycle depending on the input voltage, started by the comparator <NUM>, such that a defined on and off time is generated. The driver device is configured to drive the power stage based on the timing signal received from the constant on timer. The power stage is configured to convert an input voltage, VIN, received through the inductor <NUM> into the output voltage, VOUT, of the boost constant on-time voltage regulator using the power FETs <NUM>, <NUM>.

<FIG> depicts an embodiment of a Buck constant on-time voltage regulator <NUM> in which the ripple generation device <NUM> of <FIG> can be used. In the embodiment depicted in <FIG>, the Buck constant on-time voltage regulator includes the ripple generation device <NUM>, a constant on timer <NUM>, a comparator <NUM>, a power stage circuit <NUM> includes power FETs <NUM>, <NUM>, a driver device <NUM>, an inductor <NUM>, a voltage summation device <NUM>, and an optional RC network <NUM>, which includes a capacitor <NUM> and resistors RC, RL. The RC network can be used as a load for the boost constant on-time voltage regulator. In some embodiments, the RC network is not a component of the boost constant on-time voltage regulator. The driver device, the power stage circuit, the comparator, and the constant on timer form a feedback control loop. The driver device is a common voltage regulator component, and consequently is not described in detail herein. In some embodiments, the driver device is implemented using at least one processor such as a microcontroller or a CPU. The constant on timer is a common voltage regulator component, and consequently is not described in detail herein. The constant on timer may be implemented by any type of on timer that can generate a timing signal having an active portion with fixed time duration. In some embodiments, the constant on timer is implemented using at least one processor such as a microcontroller or a CPU. The Buck constant on-time voltage regulator converts an input voltage, VIN, into an output voltage, VOUT, which is lower than the input voltage, VIN. Although the Buck constant on-time voltage regulator is shown in <FIG> as including certain components, in some embodiments, the Buck constant on-time voltage regulator includes less or more components to implement less or more functionalities.

In the embodiment depicted in <FIG>, the ripple generation device <NUM> is configured to generate a ripple signal for the buck constant on-time voltage regulator <NUM>. The voltage summation device <NUM> is configured to sum up the voltage of the ripple signal that is generated by the ripple generation device with the output voltage, VOUT, of the buck constant on-time voltage regulator. The comparator <NUM> is configured to compare the result from the voltage summation device with a reference voltage, Vref. The constant on timer <NUM> is configured to provide an active and inactive cycle depending on the input voltage, started by the comparator <NUM>, such that a defined on and off time is generated. In some embodiments, the constant on timer generates a timing signal with a constant on time. The driver device is configured to drive the power stage based on the timing signal received from the constant on timer. The power stage and the inductor <NUM> are configured to convert an input voltage, VIN, into the output voltage, VOUT, of the buck constant on-time voltage regulator using the power FETs <NUM>, <NUM>.

<FIG> is a process flow diagram of a method for ripple generation for a constant on-time voltage regulator in accordance with an embodiment of the invention. At block <NUM>, a ripple signal is generated. At block <NUM>, a difference between an amplitude of the ripple signal and at least one reference amplitude is detected. At block <NUM>, a control signal for controlling the amplitude of the ripple signal is generated based on the detected difference. The constant on-time voltage regulator may be similar to or the same as the boost constant on-time voltage regulator <NUM> depicted in <FIG> and/or the buck constant on-time voltage regulator <NUM> depicted in <FIG>. Embodiments of ripple generation devices for a constant on-time voltage regulator and methods for ripple generation for a constant on-time voltage regulator are described. In one embodiment, a ripple generation device for a constant on-time voltage regulator includes a ripple generator configured to generate a ripple signal, a detector operably connected to the ripple generator and configured to detect a difference between an amplitude of the ripple signal and at least one reference amplitude and a feedback controller operably connected to the ripple generator and the detector and configured to generate a control signal for controlling the amplitude of the ripple signal based on the detected difference. Other embodiments are also described.

Although the operations of the method herein are shown and described in a particular order, the order of the operations of the method may be altered so that certain operations may be performed in an inverse order or so that certain operations may be performed, at least in part, concurrently with other operations.

In addition, although specific embodiments of the invention that have been described or depicted include several components described or depicted herein, other embodiments of the invention may include fewer or more components to implement less or more features.

Claim 1:
A ripple generation device (<NUM>) for a constant on-time voltage regulator, the ripple generation device (<NUM>) comprising:
a ripple generator (<NUM>) configured to generate a ripple signal;
a detector (<NUM>) operably connected to the ripple generator (<NUM>) and configured to detect a difference between a voltage of the ripple signal and a first reference voltage and a second reference voltage; and
a feedback controller (<NUM>) operably connected to the ripple generator (<NUM>) and the detector (<NUM>) and configured to generate a control signal for controlling the voltage of the ripple signal based on: (i) the detected difference, and (ii) a bias voltage receivable from an output of the constant on-time voltage regulator;
wherein:
if the voltage of the ripple signal is larger than the first reference voltage, then the feedback controller (<NUM>) is configured to generate the control signal for reducing the voltage of the ripple signal; and
if the voltage of the ripple signal is smaller than the second reference voltage, then the feedback controller (<NUM>) is configured to generate the control signal for increasing the voltage of the ripple signal.