A 100M–1.5 GHz harmonic-rejection SDR receiver front-end

A 0.1-1.5 GHz harmonic-rejection software-defined radio (SDR) receiver front-end is presented. The front-end consists of a wideband LNA with the differential feedback inverter configuration and a harmonic rejection mixer with three Gilbert mixer paths. By using the feedback resistor, the LNA shows wideband input impedance matching characteristics and good gain and NF performance. Based on the detailed harmonic rejection analysis, a harmonic rejection mixer is presented. In order to make the harmonic rejection robust to gain and phase mismatch, the gm cells are set in array to calibrate the conversion gain of each mixer and realize the vector calibration which significantly improves the harmonic rejection ratio. The proposed RF front-end achieves an input impedance matching S11 <;-10 dB, NF <;2.6 dB and a conversion gain higher than 30dB. The third and fifth harmonics can be attenuated by higher than 40dB before the calibration. With the gm calibration method, the HRR can achieve ~60dB. The front-end consumes 13-15.1 mA current.