A Near-Threshold Energy-Efficient ASK Transmitter for Biomedical Implants

A near-threshold amplitude shift keying (NT-ASK) transmitter for biomedical implants is presented in this paper. The ASK transmitter supports a 100-Mb/s baseband data rate with a carrier frequency of 2.4 GHz. The design incorporates an LC voltage-controlled oscillator (VCO), ASK modulator, and a class-E power amplifier. The carrier is generated by a low phase noise LC-VCO, and then directly modulated by an NT-ASK modulator. The modulated signal is amplified by a class-E power amplifier and transmitted through an inductive coil. The transmitter achieves a total power consumption of 1.65 mW at 0.5 V, an energy efficiency of 16.5 pJ/b, and a phase noise of -115.7 dBc/Hz at 1-MHz offset at a center frequency of 2.4 GHz. The output power level of the transmitter is -14 dBm. The ASK transmitter is implemented in a standard 0.13-μm CMOS process with a core area of 0.63 mm
²
.