Patent ID: 7308244
Filing Date: 2007-12-11
Classification: H03D

Abstract:
1. A mixer comprising: a pair of low frequency mixer inputs for receiving a low frequency input signal therebetween; a pair of high frequency mixer inputs for receiving a high frequency input signal therebetween; a pair of mixer outputs; four switching units, each switching unit comprising a low frequency switching unit input, a high frequency switching unit input, a switching unit output, a node connected via a high pass filter to the respective high frequency switching unit input and via a low pass filter to the respective low frequency switching unit input and a switching device arranged to provide an output at the respective switching unit output in dependence on the voltage at the respective node; and the mixer further comprising: a first feedback loop responsive to the voltage at the first low frequency mixer input and arranged to regulate the current through the outputs of the first and second ones of the switching units so that the total current through the outputs of the first and second ones of the switching units is substantially proportional to the voltage at the first low frequency mixer input; and a second feedback loop responsive to the voltage at the second low frequency mixer input and arranged to regulate the current through the outputs of the third and fourth ones of the switching units so that the total current through the outputs of the third and fourth ones of the switching units is substantially proportional to the voltage at the second low frequency mixer input.