High linearity transconductance amplifier

Abstract

The high-linearity transconductance amplifier includes a first transistor, a second transistor, two source resistors, a load, a common-mode voltage correction device, and a common-mode voltage correction circuit. The first and second transistors generate a pair of output currents to the load. The two source resistors are connected in series between the sources of the first and second transistors, and the sources of the first and second transistors have first and second source voltages, respectively. The common-mode voltage correction circuit compares the input common-mode voltage with a reference voltage and counts based on the comparison result to adjust the input common-mode voltage, wherein the input common-mode voltage is related to the first and second source voltages. The common-mode voltage correction device provides a bias voltage to the load based on the system high voltage and the counting result of the common-mode voltage correction circuit.

Claims

1. A high linearity transconductance amplifier, comprising: A differential pair for receiving a pair of input voltages and generating a pair of output currents, wherein the differential pair includes a first transistor and a second transistor; Two source resistors, connected in series between the sources of the first transistor and the second transistor, wherein the sources of the first transistor and the second transistor have a first source voltage and a second source voltage, respectively; a load, coupled to the differential pair to receive the output current of the pair; a common-mode voltage correction circuit for comparing an input common-mode voltage with a reference voltage and counting based on the comparison result to adjust the input common-mode voltage, wherein the input common-mode voltage is associated with the first source voltage and the second source voltage; and a common-mode voltage correction device, coupled to the load and biased to a system high voltage, for providing a bias voltage to the load.

2. The high linearity transconductance amplifier as claimed in claim 1, wherein the value of the reference voltage is approximately a drain-source voltage at the boundary between the linear region and the saturation region of the first transistor or the second transistor.

3. The high linearity transconductance amplifier as described in claim 1, wherein the common-mode voltage correction circuit includes: A comparator is used to compare the input common-mode voltage with the reference voltage and generate a comparison result accordingly; and a counter, coupled to the comparator, for counting based on the comparison result and generating a count result accordingly.

4. The high linearity transconductance amplifier as described in claim 3, wherein the comparator is used to compare the input common-mode voltage with the reference voltage based on a clock signal, and wherein the counter is used to count based on the clock signal.

5. The high linearity transconductance amplifier as described in claim 3, wherein the common-mode voltage correction circuit further comprises: An input common-mode voltage generation circuit is coupled to the counter and used to select one of a plurality of reference voltage values ​​as the input common-mode voltage based on the counting result.

6. The high linearity transconductance amplifier as described in claim 5, wherein the input common-mode voltage generation circuit includes: A current source is used to generate a current; a plurality of resistors are connected in series and coupled to the current source. and a plurality of switches for turning on one of the switches according to the counting result, wherein one end of each of the switches is coupled between two adjacent resistors and has one of the reference voltage values, wherein the other end of each of the switches is used to provide the input common-mode voltage.

7. The high linearity transconductance amplifier as claimed in claim 3, wherein the common-mode voltage correction device is coupled between the comparator and the load, and is used to provide the bias voltage to the load based on the system high voltage and the comparison result.

8. The high linearity transconductance amplifier as claimed in claim 7, wherein the common-mode voltage correction device includes a transistor switch, the gate of which receives the comparison result, the source of which receives the system high voltage, and the drain of which provides the bias voltage to the load.

9. The high linearity transconductance amplifier as claimed in claim 1, wherein the common-mode voltage correction device is coupled between the common-mode voltage correction circuit and the load, and is used to provide the bias voltage to the load based on the system high voltage and the counting result of the common-mode voltage correction circuit.

10. A high linearity transconductance amplifier, comprising: A first transistor for receiving a first input voltage and generating a first output current accordingly; A second transistor for receiving a second input voltage and generating a second output current, wherein the first transistor and the second transistor form a differential pair; two source resistors connected in series between the sources of the first transistor and the second transistor, wherein the sources of the first transistor and the second transistor have a first source voltage and a second source voltage, respectively; a load coupled to the differential pair to receive the first output current and the second output current; a common-mode voltage correction device coupled to the load and biased to a system high voltage, and for providing a bias voltage to the load; and a common-mode voltage correction circuit for comparing an input common-mode voltage with a reference voltage, wherein the common-mode voltage correction device provides the bias voltage based on the comparison result, wherein the input common-mode voltage is associated with the first source voltage and the second source voltage.

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