Techniques for controlling an auto-zero amplifier
AssigneeAnalog Devices International Unlimited Company
InventorsHai Chen, Gregory J. Hughes
Life of this patent
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Abstract
This disclosure describes auto-zero amplifier circuit that include an additional capacitor (or other capacitive component) that can be switchably coupler to a reference voltage. The auto-zero amplifier circuit can generate an auto-zero compensation signal using a difference between the reference voltage stored on the additional capacitor and a voltage stored on another auto-zero capacitor.
Claims19
An auto-zero amplifier circuit to compensate for offset drift, and generate an output signal, the circuit comprising:
- a first amplifier circuit having a first input offset voltage;
- a second amplifier circuit having a second input offset voltage;
- a first auto-zero capacitor switchably coupled, using a first switch, to the first amplifier circuit to receive and store a first reference voltage;
- a second auto-zero capacitor switchably coupled, using a second switch, to the second amplifier circuit to receive and store the first input offset voltage,
- wherein the first amplifier circuit is coupled to generate a first amplifier circuit compensation signal using a difference between the first input offset voltage and the first reference voltage;
- a third auto-zero capacitor switchably coupled, using a third switch, to the second amplifier circuit to receive and store the second input offset voltage;
- and
- a fourth auto-zero capacitor switchably coupled, using a fourth switch, to the second amplifier circuit to receive and store a second reference voltage,
- wherein the second amplifier circuit is coupled to generate a second compensation signal using a difference between the second input offset voltage stored on the third auto-zero capacitor and the second reference voltage stored on the fourth auto-zero capacitor, and
- wherein an output of the second amplifier circuit is coupled to a nulling input of the first amplifier circuit, and an output of the first amplifier circuit to generate the output signal.
A method of compensating an auto-zero amplifier circuit for offset drift and generate an output signal, the method comprising:
- coupling, using a first switch, a first auto-zero capacitor to a first amplifier circuit to receive and store a first reference voltage;
- coupling, using a second switch, a second auto-zero capacitor to a second amplifier circuit to receive and store a first input offset voltage of the first amplifier circuit;
- and
- generating a first compensation signal using a difference between the first input offset voltage and the first reference voltage,
- coupling, using a third switch, a third auto-zero capacitor to the second amplifier circuit to receive and store a second input offset voltage of the second amplifier circuit;
- coupling, using a fourth switch, a fourth auto-zero capacitor to the second amplifier circuit to receive and store a second reference voltage;
- generating a second compensation signal using a difference between the second input offset voltage and the second reference voltage;
- coupling an output of the second amplifier circuit to a nulling input of the first amplifier circuit;
- and
- generating the output signal using an output of the first amplifier circuit.
An auto-zero amplifier circuit to compensate for offset drift and generate an output signal, the circuit comprising:
- a first amplifier circuit having a first input offset voltage;
- means for storing a first input offset voltage of the first amplifier circuit;
- means for storing a first reference voltage,
- wherein the first amplifier circuit is coupled to generate a first amplifier circuit compensation signal using a difference between the stored first input offset voltage and the stored first reference voltage,
- a second amplifier circuit having a second input offset voltage;
- means for storing the second input offset voltage;
- and
- means for storing a second reference voltage,
- wherein the second amplifier circuit is coupled to generate a second compensation signal using a difference between the stored second input offset voltage and the stored second reference voltage,
- wherein an output of the second amplifier circuit is coupled to a nulling input of the first amplifier circuit, and an output of the first amplifier circuit to generate the output signal.
Dependencies are inferred from the claim text.