A PLL-based BFSK transmitter with reconfigurable and PVT-tolerant class-C PA for medradio & ISM (433MHz) standards

An RF transmitter that uses closed-loop PLL-based BFSK modulation and is reconfigurable for both the MedRadio (402-405MHz) and 433 MHz ISM bands is introduced. Innovations include the first reconfigurable class-C PA, the first class-C PA with automatic calibration against PVT variations, and a low-power NMOS delay-based ring-VCO PLL. Several performance records are achieved: (1) The PA realizes a peak efficiency of 47% in the high-power (ISM) (-2 dBm) mode and 43% (33%) in the MedRadio -12 dBm (-16 dBm backoff) modes. (2) The PLL dissipates only 72 μW with a phase noise of-111 dBc/Hz @ 1 MHz, and (3) the overall transmit efficiencies are 29% and 17% for the -12 dBm and -16 dBm backoff levels for the MedRadio band and 44% for the ISM (433 MHz) bands.