An RF powered, wireless temperature sensor in quarter micron CMOS

We present a wireless CMOS temperature sensor that gathers power through RF power telemetry, and transmits data wirelessly at 2.3 GHz to a base station. Power is gathered by a low threshold voltage rectifier-multiplier circuit decreasing the minimum incident peak signal amplitude required at the receiving port compared to the state of the art power telemetry systems. A low power integrated LC voltage controlled oscillator (VCO) lies at the heart of the system. The oscillation frequency of the VCO is modulated by change in the ambient temperature, and is transmitted via an integrated power amplifier. The measured phase noise of the oscillator is -101 dBc/Hz (@1 MHz offset) while consuming 400 μA, achieving a figure of merit of 171 dBc/Hz. A linear temperature sensitivity of 126 ppm/°C is achieved with a total sensor current consumption of 1.1 mA.