Mixer-amplifier for e.g. mobile telephone set, has filter arranged between parallel branches and modifying current circulating in source current circuit during detection of imbalance between branches by comparator

摘要

The mixer-amplifier has amplifying and mixing stages jointly serving to amplify an incident signal and to transpose a frequency of the signal to an intermediate frequency (Fi). A trap filter (B) is arranged between parallel branches (B1, B2) connected to a P-channel MOS transistor (T9), and has a comparator (A) detecting an imbalance between the branches. The filter modifies a current circulating in a source current circuit, formed of N-channel MOS transistors of the amplifying stage, during detection of the imbalance, where the mixer-amplifier is obtained from double balanced Gilbert cells.