Design and Analysis of a Programmable Receiver Front End Based on Baseband Analog-FIR Filtering Using an LPTV Resistor

This paper presents a programmable receiver front-end that uses periodically time-varying components. A sharp programmable filtering response was achieved at RF using a linear periodically time-varying (LPTV) resistor in conjunction with a passive mixer and an integrate-and-dump circuit. The LPTV resistor along with the integrate-and-dump circuit is shown to achieve a programmable finite-impulse response (FIR) baseband filter. The baseband filter is then upconverted with the passive mixer to achieve sharp bandpass filtering at the desired RF center frequency. Further, it is shown that an additional S-11 constraint can be imposed on the FIR filter design to allow for impedance matching to the antenna impedance. The implemented receiver achieved high close-in linearity with > 17 dBm of IIP3 at only 1.2x bandwidth frequency offset, while achieving a wideband impedance match with S-11 better than -10 dB throughout the local oscillator range of 0.1-1 GHz.