A 10.7 MHz CMOS SC radio IF filter with variable gain and a Q of 55

Low-cost low-power fully-integrated receivers are desirable for portable radio applications. CMOS offers integration of both receiver and digital processing circuitry on a single chip, if an extremely accurate and fully integrated CMOS IF filter is available. As the RF gain control range is limited in CMOS designs, an IF filter that can provide some of this gain control is preferred. A general simplified FM receiver chain is shown as well as application of the switched-capacitor (SC) IF filter. This high-Q 10.7 MHz SC filter exceeds the accuracy of ceramic filters for radio applications. It also provides a 36 dB IF gain control.