Method and device for implementing tracking filters and rf front end of software defined radios

Abstract

A tracking circuit has first and second filters controlled by clock signals and a combiner. Each filter has N paths in parallel between an input and an output, each path comprising a respective first/second sub-circuit and a switch (N is an integer >1). The clock signals selectively control each of the N switches of the first and second filters at a same frequency, and in variously described embodiments the first and second on-time durations may be different, the first and second sub-circuits may be different, or both first/second on-time durations and first/second sub-circuits may be different. Signals output from the first and second filter are added at a combiner. In certain examples each path in the first and second filter is controlled by same-phase clock signals, and every path on either filter are controlled with different-phase clock signals.