Standby regulator
View Patent ↗A standby regulator circuit includes a standby bias circuit and a standby operational amplifier. The standby regulator circuit provides a standby regulated control voltage to a multiplexer. A regular operational amplifier provides a regulated control voltage to the multiplexer. During regular operation, the multiplexer selects the regular operational amplifier and selects the standby regulator circuit in a low-power mode. The multiplexer couples to a native pass transistor gate having a threshold voltage about equal to 0 V. The native pass transistor provides a regulated output voltage with relatively low-level input control voltages. In low-power mode, a power-down signal, provided to the multiplexer, smoothly transitions regulated control voltage from the regular operational amplifier to regulated control voltage sourcing from the standby operational amplifier. In low-power operation regular operational amplifier power is saved and the standby operational amplifier is appropriate for regulating the low threshold voltage native pass transistor.
1. A voltage regulator system, comprising:
a biasing module, operable to generate a first reference biasing signal using a first magnitude of power;
a first amplifier module, operable to generate a first regulated control signal as a function of the first reference biasing signal;
a second amplifier module, operable to generate a second regulated control signal as a function of a second reference biasing signal, the second reference biasing signal being generated using a second magnitude of power that is higher than the first magnitude of power;
a standby detect module, operable to detect an operational condition being selected from a group consisting of a regular mode and a standby mode, and to output a selector input signal as a function of the operational condition;
a selector module, operable to receive the first regulated control signal and the second regulated control signal, and to output a selector output signal as a function of the selector input signal, such that:
when the operational condition is the standby mode, the selector output signal is a function of the first regulated control signal; and
when the operational condition is the regular mode, the selector output signal is a function of the second regulated control signal; and
an output module operable to receive a source voltage and to output a regulated output voltage as a function of the selector output signal, the output voltage being lower than the source voltage.
2. The voltage regulator system of claim 1 , wherein:
the biasing module comprises a bandgap reference generator unit operable to generate a bandgap reference; and
the first reference biasing signal is generated as a function of the bandgap reference.
3. The voltage regulator system of claim 2 , wherein:
the standby detect module is further operable to generate a bias startup signal indicating the operating condition; and
the biasing module further comprises a startup unit operable to:
detect the bias startup signal; and
start up the bandgap reference generator when the bias startup signal indicates that the operating condition is the standby mode.
4. The voltage regulator system of claim 2 , wherein the biasing module further comprises a reference ready detect unit operable to:
detect whether the first reference biasing signal is valid for use as a reference level; and
when the first reference biasing signal is valid for use as a reference level, output a reference ready signal.
5. The voltage regulator system of claim 4 ,
wherein detecting whether the first reference biasing signal is valid for use as a reference level comprises detecting whether the first reference biasing signal is greater than a threshold level.
6. The voltage regulator system of claim 4 , wherein:
the reference ready detect unit comprises a delay unit operable to provide a magnitude of delay; and
detecting whether the first reference biasing signal is valid for use as a reference level comprises waiting for a duration of time that is greater than or equal to the magnitude of delay.
7. The voltage regulator system of claim 4 , wherein the standby detect module is further operable to:
receive the reference ready signal; and
output the selector input signal as a function of the operational condition only when the reference ready signal indicates that the first reference biasing signal is valid for use as a reference level.
8. The voltage regulator system of claim 4 , wherein the standby detect module is further operable to:
receive the reference ready signal; and
direct the first amplifier module to start up when the reference ready signal indicates that the first reference biasing signal is valid for use as a reference level.
9. The voltage regulator system of claim 1 , wherein:
the first amplifier module is further operable to generate the first regulated control signal in negative feedback as a function of the first reference biasing signal and a first feedback signal, the first feedback signal being generated as a function of the regulated output voltage.
10. The voltage regulator system of claim 9 , wherein the first feedback signal is tied to the regulated output voltage.
11. The voltage regulator system of claim 1 , wherein:
the second amplifier module is further operable to generate the second regulated control signal in negative feedback as a function of the second reference biasing signal and a second feedback signal, the second feedback signal being generated as a function of the regulated output voltage.
12. The voltage regulator system of claim 1 , wherein the second reference biasing signal is generated as a function of an external biasing signal generated by an external biasing module communicatively coupled with the second amplifier module.
13. The voltage regulator system of claim 1 , wherein the selector module comprises a multiplexer.
14. The voltage regulator system of claim 1 , wherein the output module comprises a low-threshold device, having:
a gate driven as a function of the selector output signal;
a first terminal coupled with the source voltage;
a second terminal coupled with the regulated output voltage; and
the native pass transistor is a field effect transistor having a threshold voltage about equal to zero volts.
15. The voltage regulator system of claim 14 , wherein the low-threshold device is a field effect transistor having a threshold voltage substantially equal to zero volts.
16. The voltage regulator system of claim 1 , wherein the output module comprises a load current path, operable to be disabled when the operational condition is the standby mode.
17. The voltage regulator system of claim 1 , wherein the output module comprises a bypass unit, operable to disable the output module as a function of an externally generated bypass signal.
18. The voltage regulator system of claim 1 , wherein:
the first reference biasing signal provides a lower accuracy reference than the second reference biasing signal.
19. A voltage regulator system, comprising:
a biasing module, operable to generate a first reference biasing signal using a first magnitude of power;
a standby detect module, operable to detect an operational condition being selected from a group consisting of a regular mode and a standby mode, and to output a selector input signal as a function of the operational condition;
a selector module, operable to:
receive the first reference biasing signal and a second reference biasing signal, the second reference biasing signal being generated using a second magnitude of power that is higher than the first magnitude of power; and
output a selector output signal as a function of the selector input signal, such that:
when the operational condition is the standby mode, the selector output signal is a function of the first reference biasing signal; and
when the operational condition is the regular mode, the selector output signal is a function of the second reference biasing signal;
an amplifier module, operable to generate a regulated control signal as a function of the selector output signal; and
an output module operable to receive a source voltage and to output a regulated output voltage as a function of the regulated control signal, the output voltage being lower than the source voltage.
20. The voltage regulator system of claim 19 , wherein:
the biasing module comprises a bandgap reference generator unit operable to generate a bandgap reference; and
the first reference biasing signal is generated as a function of the bandgap reference.
21. The voltage regulator system of claim 20 , wherein:
the standby detect module is further operable to generate a bias startup signal indicating the operating condition; and
the biasing module further comprises a startup unit operable to:
detect the bias startup signal; and
start up the bandgap reference generator when the bias startup signal indicates that the operating condition is the standby mode.
22. The voltage regulator system of claim 20 , wherein the biasing module further comprises a reference ready detect unit operable to:
detect whether the first reference biasing signal is valid for use as a reference level; and
when the first reference biasing signal is valid for use as a reference level, output a reference ready signal.
23. The voltage regulator system of claim 22 , wherein the standby detect module is further operable to:
receive the reference ready signal; and
output the selector input signal as a function of the operational condition only when the reference ready signal indicates that the first reference biasing signal is valid for use as a reference level.
24. The voltage regulator system of claim 19 , wherein:
the amplifier module is further operable to generate the regulated control signal in negative feedback as a function of the first reference biasing signal and a feedback signal, the feedback signal being generated as a function of the regulated output voltage.
25. The voltage regulator system of claim 19 , wherein the second reference biasing signal is generated as a function of an external biasing signal generated by an external biasing module communicatively coupled with the selector module.
26. A method for voltage regulation, comprising:
configuring a voltage regulator to generate a regulated output voltage as a function of a second reference biasing signal;
monitoring an operational condition to detect a transition from a regular mode to a standby mode;
directing a biasing module to generate a first reference biasing signal when the transition from the regular mode to the standby mode is detected;
monitoring the first reference biasing signal to determine when the first reference biasing signal is valid for use as a reference level, the first reference biasing signal being generated using less power than used to generate the second reference biasing signal; and
when the first reference biasing signal is valid for use as a reference level, reconfiguring the voltage regulator to generate the regulated output voltage as a function of the first reference biasing signal.
27. The method of claim 26 , further comprising:
when the transition from the regular mode to the standby mode is detected, using an amplifier module to generate a regulated control signal as a function of the first reference biasing signal,
wherein reconfiguring the voltage regulator to generate the regulated output voltage as a function of the first reference biasing signal comprises reconfiguring the voltage regulator to generate the regulated output voltage as a function of the regulated control signal.
28. The method of claim 26 , further comprising:
using a first amplifier module to generate a first regulated control signal as a function of the first reference biasing signal; and
using a second amplifier module to generate a second regulated control signal as a function of the second reference biasing signal,
wherein configuring the voltage regulator to generate the regulated output voltage as a function of the second reference biasing signal comprises configuring the voltage regulator to generate the regulated output voltage as a function of the second regulated control signal, and
wherein reconfiguring the voltage regulator to generate the regulated output voltage as a function of the first reference biasing signal comprises reconfiguring the voltage regulator to generate the regulated output voltage as a function of the regulated control signal.
29. The method of claim 28 , wherein using the second amplifier module to generate the second regulated control signal as a function of the second reference biasing signal comprises:
when the first reference biasing signal is valid for use as a reference level, directing the second amplifier module to generate the second regulated control signal as a function of the second reference biasing signal.
30. The method of claim 28 , further comprising:
after reconfiguring the voltage regulator to generate the regulated output voltage as a function of the first reference biasing signal, shutting down the first amplifier module.
31. The method of claim 28 , further comprising:
after reconfiguring the voltage regulator to generate the regulated output voltage as a function of the first reference biasing signal, reducing a magnitude of load current drawn by the voltage regulator.
32. The method of claim 26 , further comprising:
monitoring the operational condition to detect a transition from the standby mode to the regular mode;
when the transition from the standby mode to the regular mode is detected, reconfiguring the voltage regulator to generate the regulated output voltage as a function of the second reference biasing signal; and
after reconfiguring the voltage regulator to generate the regulated output voltage as a function of the second reference biasing signal, directing the biasing module to stop generating the first reference biasing signal.
33. The method of claim 32 , further comprising:
when the transition from the standby mode to the regular mode is detected, monitoring the second reference biasing signal to determine when the second reference biasing signal is valid for use as a reference level,
wherein the voltage regulator is reconfigured to generate the regulated output voltage as a function of the second reference biasing signal only when the second reference biasing signal is valid for use as a reference level.