Tunable wideband SAW-less receiver front-end in 65 nm CMOS

A surface acoustic wave-less receiver front-end for GSM, TD-LTE and TD-SCDMA standards featuring a novel low noise amplifier (LNA) architecture and harmonic rejection technique is presented. The two-stage LNA uses capacitive feedback in the first stage for wideband input matching. It can operate from 500 MHz up to 2.5 GHz with an S-11 below -15 dB. The harmonic rejection mixer structure operates using two- and four-phase local oscillator signals and is capable of achieving a high harmonic rejection over a wide channel bandwidth. The average harmonic rejection is above 60 dB measured over a 20 MHz LTE channel and above 70 dB over a GSM channel. The mixer structure contains digitally tunable resistor and capacitor banks for precise tuning, causing the peak harmonic rejection in the channel to exceed 80 dB. The precise tuning capability ensures good harmonic rejection in the presence of process mismatch and duty cycle mismatch. The 1-dB received signal compression point with a blocker present at 20/80 MHz offset for low-/high-band is 0 and +2 dBm, respectively. In-band IIP3, and IIP2 are -14.8 and > 49 dBm, respectively, for low-band. For high-band they are -18.2 and > 44 dBm. Implemented in 65 nm CMOS, the complete front-end consumes 80 mW of power.