A 9.4 pJ/bit 432 MHz 16-QAM/MSK transmitter based on edge-combining power amplifier

An energy-efficiency 16-QAM/MSK transmitter (TX) working at 432 MHz is presented for the short range communications. By adopting the edge-combining power amplifier (ECPA), only an injection-locked ringing oscillator (ILRO) with very low frequency is required, in comparison to the high frequency local oscillator in conventional TX's, which helps to reduce the power consumption of this TX significantly. A new method to control the amplitude of the edge-combined quadrature signals is proposed to generate the 16-quadrature amplitude modulation (16-QAM) and minimum shift keying (MSK) modulations in this work. A finite impulse response (FIR) filter is introduced in the ECPA for side lobe suppression enhancement. Implemented in a 0.18 μm CMOS process, the proposed TX consumes 468 μW when outputting -15 dBm 50 Mbps 16-QAM/MSK signals in simulation. Under 1 V supply, the TX can achieve an energy efficiency of 9.4 pJ/bit at the maximum data rate of 50 Mbps. The phase noise of the RF output in the injection-locked state is -103 dBc/Hz, at 1MHz offset.