Analysis and Design of a 20 MHz Bandwidth, 50.5 dBm OOB-IIP3, 5.4mW TIA for SAW-Less Receivers

A power-efficient transimpedance amplifier with wide channel bandwidth is proposed to meet the stringent linearity requirements of surface acoustic wave-less frequency-division duplexing receivers. A unity-gain loop bandwidth of 1.6 GHz is achieved with low-power dissipation. This was done without using any internal compensation but relying on zeros, both within the operational transconductance amplifier and in the feedback network, to ensure stability across all parameter variations. A simple non-linear analysis methodology is presented that provides important insights, useful for the design optimization. The prototype, implemented in 28-nm CMOS technology, has 14 dB of gain with 20-MHz bandwidth and achieves 21.1-μV in-band noise together with 33 and 50.5-dBm IIP3 at 6 and 100-MHz offset, respectively, while requiring only 5.4 mW. The corresponding filter figure of merit (FOM) of 183.2 dBJ⁻¹ at 100-MHz offset exceeds that of all previous designs. Simulation shows that an even better FOM could be achieved using a larger width (more linear) feedback resistor. Finally, the differential input impedance is less than 33 Ω at all frequencies.