US Patent 7483684 Mixer

To realize a mixer with a charge subsampling circuit with which a base band signal can be readily obtained without being affected by noise from wide bandwidth signals or undesired signals. A current generating circuit 8 outputs a current in proportion to the input signal voltage. In response to a control signal from the timing generating block 6, a charge subsampling circuit 7 samples the current at the same sampling frequency as the carrier frequency. In a charge-integrating process accompanying the sampling, weighting is carried out on terms in the transfer function of the FIR filter using a set of selected weights.