A low-power, high data-rate CMOS ASK transmitter for wireless capsule endoscopy

This paper presents a low-power, high data-rate amplitude shift keying (ASK) radio frequency transmitter for wireless capsule endoscopy. This transmitter consists of a complementary LC voltage-controlled oscillator to generate the 900 MHz carrier frequency and a switchable driver amplifier (DA) controlled by the digital baseband signal to implement the direct ASK modulation. The modulated signal is amplified by the DA and radiated out by a miniaturized coil antenna. The proposed transmitter is implemented in a commercial 0.18-μm CMOS process with 0.32 mm² active area. Measurement results show that the peak output power is 1 dBm in the 902-928 MHz ISM band and the average DC power consumption is 7.2 mW at a data rate of 15 Mbps.