A 17pJ/bit 915MHz 8PSK/O-QPSK transmitter for high data rate biomedical applications

A 915MHz 8PSK/O-QPSK transmitter for high data rate biomedical applications is presented in this paper. The transmitter architecture is based on a sub-harmonic injection-locked ring oscillator and a direct modulated power amplifier to simplify the architecture and reduce the power consumption while achieving spectral efficient modulation. The spurious performance of the injection-locked ring oscillator and the impact of circuit non-idealities on the transmitter performance are also discussed. Fabricated prototype in 65nm CMOS consumes only 938μW at the data rate of 55Mbps and achieves energy efficiency of 17pJ/bit which is the lowest reported to date. The chip occupies an active area of 0.038mm². The measured EVM is better than 3.8% in 8PSK mode (at 55Mbps) while delivering -15dBm of output power.