Circuit and method for providing a reference signal
An integrated circuit for providing a reference signal to a regulator includes a comparison circuit and a first reference signal adjustor. The comparison circuit is configured to output a control signal based on a difference between levels of a constraint signal of the regulator, such as an input voltage signal or a supply voltage signal, and the reference signal. The regulator has a feedback control loop maintained by the reference signal. The first reference signal adjustor is operatively coupled to the comparison circuit and is configured to adjust the level of the reference signal based on the control signal such that the level of the reference signal increases toward a preset level and does not cause the feedback control loop of the regulator to become saturated when the regulator is in a start-up phase.
1. An integrated circuit for providing a reference signal to a regulator, comprising:
a comparison circuit configured to output a control signal based on a difference between levels of a constraint signal of the regulator and the reference signal, the regulator having a feedback control loop maintained by the reference signal;
a first reference signal adjustor operatively coupled to the comparison circuit, configured to adjust the level of the reference signal based on the control signal such that the level of the reference signal increases toward a preset level and does not cause the feedback control loop of the regulator to become saturated when the regulator is in a start-up phase; and
a second reference signal adjustor operatively coupled to the first reference signal adjustor, configured to maintain the reference signal at the preset level when the regulator is in a steady-state phase.
2. The integrated circuit of claim 1 , wherein the first reference signal adjustor comprises:
a capacitor configured to provide the reference signal at one end thereof; and
a charging controller operatively coupled to the capacitor, configured to control a slew-rate of the reference signal by adjusting charging of the capacitor based on the control signal from the comparison circuit.
3. The integrated circuit of claim 2 , wherein the charging controller comprises:
a current source configured to generate a constant current signal; and
a transistor operatively coupled to the comparison circuit, the current source, and the capacitor, configured to:
operate in a linear mode such that a level of a charging current signal applied to the capacitor is substantially equal to a level of the constant current signal if the level of the reference signal does not exceed the level of the constraint signal, and
operate in a saturation mode such that the level of the charging current signal applied to the capacitor is adjusted based on the difference between the levels of the reference signal and the constraint signal if the level of the reference signal exceeds the level of the constraint signal.
4. The integrated circuit of claim 2 , wherein the charging controller comprises:
a current controller operatively coupled to the comparison circuit, configured to:
provide a control current signal at an initial level if the level of the reference signal does not exceed the level of the constraint signal, and
adjust a level of the control current signal based on the difference between the levels of the reference signal and the constraint signal if the level of the reference signal exceeds the level of the constraint signal; and
a current mirror operatively coupled to the current controller and the capacitor, configured to generate a charging current signal at a level substantially equal to the level of the control current signal.
5. The integrated circuit of claim 4 , wherein the current controller comprises:
a current source comprising an amplifier, a first transistor, and a resistor, the current source configured to determine the initial level of the control current signal based on a control voltage signal; and
a second transistor operatively coupled to the current source, configured to switch between a saturation mode and a linear mode for adjusting the level of the control current signal based on the difference between the levels of the reference signal and the constraint signal.
6. The integrated circuit of claim 1 , wherein
the constraint signal includes an input voltage signal of the regulator; and
the level of the reference signal is adjusted based on the control signal such that the level of the reference signal does not exceed the level of the input voltage signal.
7. The integrated circuit of claim 1 , wherein
the constraint signal includes a supply voltage signal of the regulator whose level is adjusted based on a headroom requirement of the feedback control loop of the regulator; and
the level of the reference signal is adjusted based on the control signal such that the level of the reference signal does not exceed the adjusted level of the supply voltage signal.
8. The integrated circuit of claim 1 , wherein the second reference signal adjustor comprises a switching module configured to turn off the first reference signal adjustor when the level of the reference signal is within an offset range from the preset level.
9. The integrated circuit of claim 2 , wherein the second reference signal adjustor comprises a voltage source at the preset level operatively coupled to the charging controller such that a maximum voltage level at the capacitor is the preset level when the capacitor is fully charged.
10. An apparatus comprising:
a regulator configured to provide an output signal and regulate the output signal at a certain level, the regulator having a feedback control loop maintained by a reference signal;
a circuit operatively coupled to the regulator, configured to receive the output signal and perform one or more functions based on the output signal at the certain level;
a power source operatively coupled to the regulator, configured to provide a constraint signal to the regulator; and
an adaptive reference signal generator operatively coupled to the regulator, configured to generate the reference signal based on the constraint signal, the adaptive reference signal generator comprising:
a comparison circuit configured to output a control signal based on a difference between levels of the constraint signal and the reference signal,
a first reference signal adjustor operatively coupled to the comparison circuit, configured to adjust the level of the reference signal based on the control signal such that the level of the reference signal increases toward a preset level and does not cause the feedback control loop of the regulator to become saturated when the regulator is in a start-up phase, and
a second reference signal adjustor operatively coupled to first reference signal adjustor, configured to maintain the reference signal at the preset level when the regulator is in a steady-state phase.
11. The apparatus of claim 10 , wherein the first reference signal adjustor comprises:
a capacitor configured to provide the reference signal at one end thereof; and
a charging controller operatively coupled to the capacitor, configured to control a slew-rate of the reference signal by adjusting charging of the capacitor based on the control signal from the comparison circuit.
12. The apparatus of claim 10 , wherein
the constraint signal includes an input voltage signal of the regulator; and
the level of the reference signal is adjusted based on the control signal such that the level of the reference signal does not exceed the level of the input voltage signal.
13. The apparatus of claim 10 , wherein
the constraint signal includes a supply voltage signal of the regulator whose level is adjusted based on a headroom requirement of the feedback control loop of the regulator; and
the level of the reference signal is adjusted based on the control signal such that the level of the reference signal does not exceed the adjusted level of the supply voltage signal.
14. The apparatus of claim 10 , wherein
the regulator is one of a voltage regulator or a current regulator;
the circuit is a processor; and
the power source is a battery.
15. A method for providing a reference signal to a regulator comprising:
receiving a constraint signal of the regulator, the regulator having a feedback control loop maintained by the reference signal;
outputting a control signal based on a difference between levels of the reference signal and the constraint signal;
adjusting charging of a capacitive component based on the control signal to provide the reference signal at one end of the capacitive component;
controlling a slew-rate of the reference signal based on the adjusting of the charging of the capacitive component;
adjusting the level of the reference signal based on the controlling of the slew-rate of the reference signal such that the level of the reference signal increases toward a preset level and does not cause the feedback control loop of the regulator to become saturated when the regulator is in a start-up phase; and
maintaining the reference signal at the preset level when the regulator is in a steady-state phase.
16. The method of claim 15 , wherein
the constraint signal includes an input voltage signal of the regulator; and
the level of the reference signal is adjusted based on the control signal such that the level of the reference signal does not exceed the level of the input voltage signal.
17. The method of claim 15 , wherein
the constraint signal includes a supply voltage signal of the regulator whose level is adjusted based on a headroom requirement of the feedback control loop of the regulator; and
the level of the reference signal is adjusted based on the control signal such that the level of the reference signal does not exceed the adjusted level of the supply voltage signal.
18. A computer readable medium storing instructions executable by one or more integrated circuit design systems that causes the one or more integrated circuit design systems to design an integrated circuit comprising:
a comparison circuit configured to output a control signal based on a difference between levels of a constraint signal and a reference signal of a regulator, the regulator having a feedback control loop maintained by the reference signal;
a first reference signal adjustor operatively coupled to the comparison circuit, configured to adjust the level of the reference signal based on the control signal such that the level of the reference signal increases toward a preset level and does not cause the feedback control loop of the regulator to become saturated when the regulator is in a start-up phase; and
a second reference signal adjustor operatively coupled to the first reference signal adjustor, configured to maintain the reference signal at the preset level when the regulator is in a steady-state phase.
19. The integrated circuit of claim 1 , wherein the comparison circuit and the first reference signal adjustor form a feedback control loop such that the level of the reference signal does not increase beyond the level of the constraint signal.
20. The apparatus of claim 10 , wherein the comparison circuit and the first reference signal adjustor form a feedback control loop such that the level of the reference signal does not increase beyond the level of the constraint signal.
21. The medium of claim 18 , wherein the comparison circuit and the first reference signal adjustor form a feedback control loop such that the level of the reference signal does not increase beyond the level of the constraint signal.
22. An integrated circuit for providing a reference signal to a regulator, comprising:
a comparison circuit configured to output a control signal based on a difference between levels of a constraint signal of the regulator and the reference signal, the regulator having a feedback control loop maintained by the reference signal; and
a first reference signal adjustor operatively coupled to the comparison circuit, configured to adjust the level of the reference signal based on the control signal such that the level of the reference signal increases toward a preset level and does not cause the feedback control loop of the regulator to become saturated when the regulator is in a start-up phase, the first reference signal adjustor comprising:
a capacitor configured to provide the reference signal at one end thereof, and
a charging controller operatively coupled to the capacitor, configured to control a slew-rate of the reference signal by adjusting charging of the capacitor based on the control signal from the comparison circuit, the charging controller comprising:
a current source configured to generate a constant current signal, and
a transistor operatively coupled to the comparison circuit, the current source, and the capacitor, configured to:
operate in a linear mode such that a level of a charging current signal applied to the capacitor is substantially equal to a level of the constant current signal if the level of the reference signal does not exceed the level of the constraint signal, and
operate in a saturation mode such that the level of the charging current signal applied to the capacitor is adjusted based on the difference between the levels of the reference signal and the constraint signal if the level of the reference signal exceeds the level of the constraint signal.
23. An integrated circuit for providing a reference signal to a regulator, comprising:
a comparison circuit configured to output a control signal based on a difference between levels of a constraint signal of the regulator and the reference signal, the regulator having a feedback control loop maintained by the reference signal; and
a first reference signal adjustor operatively coupled to the comparison circuit, configured to adjust the level of the reference signal based on the control signal such that the level of the reference signal increases toward a preset level and does not cause the feedback control loop of the regulator to become saturated when the regulator is in a start-up phase, the first reference signal adjustor comprising:
a capacitor configured to provide the reference signal at one end thereof, and
a charging controller operatively coupled to the capacitor, configured to control a slew-rate of the reference signal by adjusting charging of the capacitor based on the control signal from the comparison circuit, the charging controller comprising:
a current controller operatively coupled to the comparison circuit, configured to:
provide a control current signal at an initial level if the level of the reference signal does not exceed the level of the constraint signal, and
adjust a level of the control current signal based on the difference between the levels of the reference signal and the constraint signal if the level of the reference signal exceeds the level of the constraint signal, and
a current mirror operatively coupled to the current controller and the capacitor, configured to generate a charging current signal at a level substantially equal to the level of the control current signal.