A tuning circuit for an RF communications system and method includes a master block that outputs a control signal to a slave block. The master block can include a first filter having a high pass filter and a low pass filter that each receive the control signal, a first rectifier coupled to the high pass filter, a second rectifier coupled to the low pass filter, and a converter coupled to the first and second rectifiers that outputs the control signal. The first filter is preferably a gm-C poly-phase filter. Output signals of the gm-C poly-phase filter include high and low pass filtering signals resulting from similarly configured circuits so that the output signals have the same electrical characteristics, which results in an increased accuracy, for example, in a cut-off frequency.