Fully differential adjustable gain devices and methods for use therewith

A method for use with a fully differential adjustable gain device, wherein the fully differential adjustable gain device includes

• differential input terminals of the fully differential adjustable gain device including a negative (−) input terminal and a positive (+) input terminal;
• differential output terminals of the fully differential adjustable gain device including a positive (+) output terminal and a negative (−) output terminal;
• fully differential signal processing circuitry including differential inputs and differential outputs, the differential inputs including a negative (−) input and a positive (+) input, the differential outputs including a positive (+) output and a negative (−) output;
• the positive (+) output of the fully differential signal processing circuitry providing the positive (+) output terminal of the fully differential adjustable gain device;
• the negative (−) output of the fully differential signal processing circuitry providing the negative (−) output terminal of the fully differential adjustable gain device;
• the method comprising:
• coupling a first cross-coupled segment between the differential input terminals of the fully differential adjustable gain device and the negative (−) input of the fully differential signal processing circuitry;
• coupling a second cross-coupled segment between the differential input terminals of the fully differential adjustable gain device and the positive (+) input of the fully differential signal processing circuitry;
• and
• adjusting a gain of the fully differential adjustable gain device, while maintaining a substantially consistent frequency response and a substantially consistent input impedance of the fully differential adjustable gain device, by adjusting one or more component values of the first and second cross-coupled segments while keeping substantially constant a specified relationship between the component values of the first and second cross-coupled segments.

A receiver, comprising:

• a low noise amplifier (LNA) configured to amplify a radio frequency (RF) signal;
• a mixer downstream of the LNA and configured to frequency down-convert the RF signal following amplification thereof by the LNA;
• and
• a fully differential adjustable gain device downstream of the mixer and configured to at least one of filter and amplify the RF signal following the frequency down-conversion thereof by the mixer, the fully differential adjustable gain device including:
• differential input terminals of the fully differential adjustable gain device including a negative (−) input terminal and a positive (+) input terminal;
• differential output terminals of the fully differential adjustable gain device including a positive (+) output terminal and a negative (−) output terminal;
• fully differential signal processing circuitry including differential inputs and differential outputs, the differential inputs including a negative (−) input and a positive (+) input, the differential outputs including a positive (+) output and a negative (−) output;
• the positive (+) output of the fully differential signal processing circuitry providing the positive (+) output terminal of the fully differential adjustable gain device;
• the negative (−) output of the fully differential signal processing circuitry providing the negative (−) output terminal of the fully differential adjustable gain device;
• a first cross-coupled segment coupled between the differential input terminals of the fully differential adjustable gain device and the negative (−) input of the fully differential signal processing circuitry;
• a second cross-coupled segment coupled between the differential input terminals of the fully differential adjustable gain device and the positive (+) input of the fully differential signal processing circuitry;
• and
• the fully differential adjustable gain device having a gain that is adjustable by adjusting one or more component values of the first and second cross-coupled segments, while maintaining a substantially consistent frequency response and a substantially consistent input impedance of the fully differential adjustable gain device, so long as a specified relationship between the component values of the first and second cross-coupled segments is kept substantially constant.