Amplifier with adjustable input and feedback resistance

A method of operating a programmable gain amplifier (PGA) circuit for adjusting a signal gain between a signal input and a signal output, the method comprising:

• comparing the signal gain to a specified signal gain;
• adjusting a fine gain control in a direction indicated by the comparison;
• and
• in response to the fine gain control reaching one of an upper limit or a lower limit, adjusting a coarse gain control in the direction indicated by the comparison and setting the fine gain control to one of the upper limit or the lower limit opposite to the limit reached, wherein the PGA circuit includes:
• a differential-input amplifier including a first input node, a second input node, and a first output node, wherein the differential-input amplifier is configured to amplify a difference in signal level between the first input node and the second input node for being provided at the first output node;
• a first configurable input impedance circuit, arranged between a first signal input node and the first input node, wherein the first configurable input impedance circuit is configured to provide a first specified input impedance value;
• and
• a first configurable feedback impedance circuit, arranged between a first signal output node and the first input node, wherein the first configurable feedback impedance circuit is configured to provide a first specified feedback impedance value.

At least one non-transitory machine-readable medium for controlling a programmable gain amplifier (PGA) circuit for adjusting a signal gain between a signal input and a signal output, including instructions, which when executed, cause processing circuitry to perform operations to:

• compare the signal gain to a specified signal gain;
• adjust a fine gain control in a direction indicated by the comparison;
• and
• in response to the fine gain control reaching one of an upper limit or a lower limit, adjust a coarse gain control in the direction indicated by the comparison and setting the fine gain control to one of the upper limit or the lower limit opposite to the limit reached, wherein the PGA circuit includes:
• a differential-input amplifier include a first input node, a second input node, and a first output node, wherein the differential-input amplifier is configured to amplify a difference in signal level between the first input node and the second input node for being provided at the first output node;
• a first configurable input impedance circuit, arranged between a first signal input node and the first input node, wherein the first configurable input impedance circuit is configured to provide a first specified input impedance value;
• and
• a first configurable feedback impedance circuit, arranged between a first signal output node and the first input node, wherein the first configurable feedback impedance circuit is configured to provide a first specified feedback impedance value.