Low-Power Wireless Transceiver With 67-nW Differential Pulse-Position Modulation Transmitter

This article presents a low-power wireless narrowband (NB) transceiver consisting of a 434-MHz NB transmitter (NBTX) and a 434-MHz NB receiver (NBRX) implemented in 0.18 μm CMOS. The NBTX utilizes differential pulse-position modulation (DPPM) to decrease consumed energy per bit (EPB) by up to 67% compared to on-off keying (OOK). The packet error performance of DPPM with a soft-decision decoding scheme is analyzed. According to the results, the packet error ratio (PER) does not deteriorate compared to OOK except at very low signal-to-noise levels. The lowest power consumption of the NBTX is 8.3 μW when DPPM data is transmitted continuously. Utilizing packet-mode transmission, the average power consumption is 67 nW at a data rate of 4.8 kbps. The transmitted data was received with a PER of 0.1% by a receiver placed at a 30-meter distance from the NBTX. With a higher power consumption of 2.5 μW at the same data rate, the estimated line-of-sight (LOS) uplink range is up to 200 meters. The NBRX is a mixer-first uncertain-IF receiver. A temperature-compensated ring oscillator (TCRO) is utilized as a local oscillator. Its measured deviation of frequency is from +0.1% to -1.2% over a temperature range from -40 to +85 °C. The NBRX utilizes Manchester encoding and the sensitivity is -87 to -82 dBm over the temperature range at a data rate of 40 kbps. The NBRX consumes 85 μW.