Analysis and Design of a 260-MHz RF Bandwidth +22-dBm OOB-IIP3 Mixer-First Receiver With Third-Order Current-Mode Filtering TIA

The design of a mixer-first wideband receiver with RF bandwidth of 260 MHz suitable for 5G applications below 6 GHz is presented. The transimpedance amplifier immediately following the passive mixer is based on a low-power modified regulated cascode with enhanced selectivity, instead of a conventional shunt-feedback architecture. At the mixer output, thanks to a positive feedback capacitance multiplication, a third-order low-pass filtering in the current domain is performed. A simplified non-linear model is used to demonstrate that, thanks to the improved selectivity, linearity close to the band edge is highly improved. Wide bandwidth, high linearity, and low power are thus achieved. Measurements on a 28-nm CMOS chip prototype show alternate channel IIP3, IIP2, and P1 dB of +22, +70, and +3 dBm, respectively. Receiver (RX) noise figure (NF) is 5.5 dB, while power consumption is 21.6 mW (in the signal path) and 7.8 mW/GHz (for local oscillator (LO) generation) with 1.8-/1.2-V supply.