Patent ID: 8010074
Filing Date: 2011-08-30
Classification: H03D,H04B

Abstract:
1. A circuit for calibrating a second order intercept point of a mixer, comprising: an oscillator circuit for providing a local oscillator signal (LO_ a mixer having IN_P and IN_M input nodes for receiving differential input signals, and output nodes for outputting differential output currents, the mixer further comprising two balanced differential pairs, in which: a digital signal processor, which receives output signals from the mixer, for generating an IIP2 calibration digital control word indicative of an optimal IIP2 setting for the mixer to compensate for imbalance in the differential output currents, thereby calibrating a value of the second order intercept point of the mixer to a maximum value; and a single digital-to-analog converter, coupled to the digital signal processor, for converting the calibration digital control word to an IIP2 correction voltage and having one output terminal, coupled to the gate of the first device, for outputting a DAC_P differential correction signal that consists of a common-mode voltage plus the IIP2 correction voltage, and having another output terminal, coupled to the gate of the fourth device, for outputting a DAC_M differential correction signal that consists of the common-mode voltage minus the IIP2 correction voltage.