An 11 pJ/Bit Multichannel OOK/FSK/QPSK Transmitter With Multi-Phase Injection-Locking and Frequency Multiplication Techniques

A 423.5-450 MHz low-power OOK/FSK/QPSK wireless transmitter is proposed with multi-phase injection locking and frequency multiplication techniques. A low-frequency phase-rotation-based frequency synthesizer is employed to provide multichannel support and FSK modulation. The far-out phase noise caused by the quantization noise of the Δ Σ modulator is filtered through a proposed N-path filter and two-stage injection-locked ring oscillators (ILROs). Phase modulation is achieved by changing the offset frequency between the oscillator free-running frequency and the injected frequency to control the steady-state phase offset of the injection-locked oscillator. Finally, a current mode class-D edge-combining power amplifier with high energy efficiency is used to achieve 5X frequency multiplication to generate the required carrier frequency. A prototype transmitter is fabricated in TSMC 90 nm CMOS process. It is shown that the device delivers an output power of -7 dBm with a power consumption of 870 μW under a 0.75 V supply voltage and supports data rates of 40/5/80 Mbps under OOK/BFSK/QPSK modulation, respectively, achieving the energy efficiency of 11 pJ/bit and 23% global efficiency.