280- μ W MICS/MedRadio CMOS Receiver Front-End for In-Vivo Biomedical Implants

This study presents an ultra-low power radio frequency receiver (RX) front-end implemented in complementary metal-oxide-semiconductor (CMOS) technology, designed for operation within the 401–406 MHz Medical Implant Communications Service (MICS) and Medical Device Radiocommunications Service (MedRadio) bands. The proposed direct-conversion RX front-end architecture incorporates a transconductance-boosted current-reuse low-noise amplifier with a feedforward capacitive-coupling technique, in-phase and quadrature complementary current-bleeding downconversion mixers with body voltage control, a two-stage passive-type polyphase filter and local oscillator buffers for quadrature LO signal generation, and output buffers. These techniques collectively enhance the overall RX front-end gain and power efficiency under constrained current consumption. Fabricated in a 65-nm CMOS technology, the implemented RX front-end occupies an active area of 0.16 mm2 (0.64 mm × 0.25 mm), excluding bonding pads. The design achieves input return losses (S11s) better than –10 dB, a conversion gain of 32.3 dB, a noise figure below 4.1 dB, an input 1-dB compression point greater than –35.5 dBm, and an input-referred third-order intercept point greater than –25.5 dBm across the targeted MICS/MedRadio band. The RX front-end draws a current of approximately 280 μA from a 1 V nominal supply.