A 0.66mW 400 MHz/900 MHz Transmitter IC for In-Body Bio-Sensing Applications

A sub-1GHz transmitter (TX) integrated chip (IC) with ultra-low power consumption and moderately high adjacent channel power rejection (ACPR) is presented for in-body bio-sensing applications. The 400 MHz 12-phase digital power amplifier (DPA) is implemented with the proposed 16QAM modulation scheme to improve the energy efficiency. The TX IC also contains a 900 MHz FSK TX realized with a symmetrical edge-combiner, which can be used in the low accuracy mode. A fully digital modulator with band shaping is integrated on the chip for the improvement of ACPR performance. Fabricated in 65-nm CMOS process, the chip occupies an active area of 0.75 mm². Under 0.5 V supply voltage, the TX consumes less than 0.66 mW power consumption while delivering -15 dBm of output power when operating at both bands. The presented TX has an energy efficiency performance comparable to the state-of-the-arts low power designs, with the measured average energy consumption of 64.5/220 pJ/bit, and the measured figure-of-merit (FoM) of 2.04/6.98 nJ/(bit · mW) for the two bands. Compared with the state-of-the-arts sub-1mW designs in literatures, the ACPR is improved by at least 13 dB.