A 150 kHz-80 MHz BW DT analog baseband for SDR RX using a 5th-order IIR LPF, active FIR and 10b 300 MS/s ADC in 28nm CMOS

Abstract

A Discrete-Time (DT) analog baseband for Software-Defined-Radio (SDR) receivers is presented. A zero-IF baseband signal at the input of a programmable gm is converted to current, which is integrated on a 5th order DT IIR filter with a bandwidth ranging from 150 kHz to 80 MHz. The IIR is followed by a DT amplifier which integrates freely selectable samples to implement active FIR filtering while simultaneously offering variable-gain amplification. This integration happens on the DAC capacitance of a 2x interleaved 10b ADC, which finally quantizes the filtered signal at a maximum rate of 300 MS/s. The 28 nm prototype achieves +10 dBm IIP3, 2 nV/VHz IRN and 52 dB gain range while consuming a maximum power of 15 mW.