Low-Power Single-Stage Narrowband Transmitter Front-End For 433-Mhz Band

This paper presents a single-stage CMOS narrowband transmitter front-end for the 433-MHz band for low-power applications. The architecture utilizes an off-chip copper loop both as an inductor in a digitally controlled LC oscillator and a radiating element. The carrier frequency can be tuned using on-chip capacitors in steps smaller than 130 kHz over a 141-MHz tuning range. Measured current consumption, drawn from a 1.2-volt supply, is 315 mu A and 2.7 nA during on-time and off-time, respectively. Approximate power of the radiated carrier signal is -27 dBm during continuous wave transmission. Due to a fast start-up time and low leakage, the front-end supports well data rates up to 5 Mbps and low-power modulation schemes where the carrier need not be generated all the time e.g. on-off keying (OOK), pulse-position modulation (PPM) and differential pulse-position modulation (DPPM).