Circuitry and methods for common-mode rejection calibration

摘要

Circuitry and methods are disclosed that may employ common mode calibration circuitry configured to at least partially calibrate out impedance differences or mismatches between the differential signal paths of differential signal circuitry. The common mode calibration circuitry may be integrated as an internal part of integrated differential signal circuitry that includes a differential amplifier to reject common mode noise, and may be used to reduce or substantially eliminate any external and/or internal difference in signal path resistance that exists between the differential signal paths of the integrated differential signal circuitry. A common mode calibration signal may be internally or externally applied to the signal inputs of differential signal circuitry, and used to determine a setting for the common mode calibration circuitry that at least partially calibrates out impedance differences or mismatches between the differential signal paths of differential signal circuitry.

主权项

1. Differential signal circuitry having at least one differential input source configured to receive positive and negative signal components of an analog differential signal pair, the differential circuitry comprising:
a differential amplifier having a positive input coupled to receive the positive signal of the analog differential signal pair across a positive signal path from the differential input source, and a negative input coupled to receive the negative signal of the analog differential signal pair across a negative signal path from the differential input source; and common mode calibration circuitry coupled within at least one of the positive signal path or negative signal path between the differential input source and the inputs of the differential amplifier, the common mode calibration circuitry being configured to programmably vary the impedance of at least one of the positive signal path or negative signal path when a difference exists between an impedance of the positive signal path and an impedance of the negative signal path so as to reduce the existing difference in signal path impedance between the positive and negative signal paths.