Voltage regulator using front and back gate biasing voltages to output stage transistor
A method involves regulating an output voltage of an output transistor of a voltage regulator circuit by providing a first voltage to a front gate of the output transistor, and simultaneously with providing the first voltage to the output transistor, providing a second voltage to a back gate of the output transistor, in a manner that regulates the output voltage around a target value.
1. A replica biased voltage regulator comprising:
an output transistor;
first and second voltage sources configured to simultaneously supply first and second voltages to a front gate and a back gate, respectively, of the output transistor; and
a control circuit to vary the second voltage on the back gate of the output transistor to maintain an output voltage of the replica biased voltage regulator around a target value.
2. The circuit of claim 1 , further comprising:
an input stage transistor coupled in series with a voltage divider network between a power supply node and ground;
the control circuit configured to compare a feedback voltage provided by the voltage divider network to a first reference voltage.
3. The circuit of claim 2 , wherein the control circuit comprises an operational amplifier coupled to provide an input feedback loop with the input stage transistor and the voltage divider network.
4. The circuit of claim 1 , further comprising:
the output transistor coupled in series with a voltage divider network between a power supply node and ground;
a load circuit coupled in parallel with the voltage divider network at an output node of the replica bias voltage regulator; and
a comparator configured to compare a feedback voltage provided by the voltage divider network to a reference voltage.
5. The circuit of claim 4 , wherein the load circuit comprises a load capacitor.
6. The circuit of claim 4 , wherein the comparator is coupled to provide an output feedback loop with the voltage divider network and the back gate of the output transistor.
7. The circuit of claim 4 , wherein the comparator is one of a linear amplifier and a non-linear voltage comparator.
8. The circuit of claim 4 , wherein the first and second voltages are each supplied from a reference voltage source.
9. The circuit of claim 4 , wherein the first voltage comprises a reference voltage supplied from a reference voltage source, and wherein the second voltage comprises a feedback voltage provided by the voltage divider network.
10. The circuit of claim 4 , wherein at least one of the first and second voltages is supplied from a band gap reference voltage source.
11. A method of load regulation in a replica biased voltage regulator circuit, the method comprising:
applying a first voltage to a front gate of an output transistor of the replica biased voltage regulator circuit simultaneously with applying a second voltage to the back gate of the output transistor; and
varying the second voltage on the back gate to regulate an output voltage of the output transistor around a target value.
12. The method of claim 11 , further comprising:
adjusting a threshold voltage of the output transistor by applying the second voltage to the back gate of the output transistor.
13. The method of claim 11 , further comprising:
generating the first voltage by applying a reference voltage and a first feedback voltage provided by an input feedback loop.
14. The method of claim 13 , further comprising:
generating the second voltage by applying the reference voltage and a second feedback voltage provided by an output feedback loop.
15. The method of claim 13 , further comprising:
generating the second voltage is by applying the first feedback voltage and a second feedback voltage provided by an output feedback loop.
16. The method of claim 15 , further comprising:
maintaining stability in the output feedback loop by way of a load capacitor coupled to the output transistor.
17. The method of claim 11 , further comprising:
generating the second voltage using a comparator.
18. The method of claim 11 , further comprising:
generating the second bias voltage by way of a non-linear voltage comparator.
19. The method of claim 18 , further comprising:
maintaining stability in the output feedback loop by way of hysteresis included within the non-linear voltage comparator.
20. A method, comprising:
regulating an output voltage of an output transistor of a voltage regulator circuit by providing a first voltage to a front gate of the output transistor, and simultaneously with providing the first voltage to the output transistor, providing a second voltage to a back gate of the output transistor, in a manner that regulates the output voltage around a target value.