Low-Power Transceiver Analog Front-End Circuits for Bidirectional High Data Rate Wireless Telemetry in Medical Endoscopy Applications

• Published in: IEEE transactions on biomedical engineering 2007-07, Vol.54 (7), p.1291-1299
• Main Authors: Chi, Baoyong, Yao, Jinke, Han, Shuguang, Xie, Xiang, Li, Guolin, Wang, Zhihua
• Format: Article
• Language: English
• Subjects: AGC; Amplifiers, Electronic; Amplitude shift keying; ASK modulator/demodulator; Capsule Endoscopes; Circuits; CMOS analog integrated circuit; Electric Power Supplies; Electronics, Medical; Endoscopes; endoscopy capsule system; Energy Transfer; Equipment Design; Equipment Failure Analysis; Integrated circuits; Low-noise amplifiers; low-power IC; Medical control systems; Radio control; Radio frequency; Radio transmitters; Radiofrequency amplifiers; RF integrated circuit; Signal Processing, Computer-Assisted - instrumentation; Telemetry; Telemetry - instrumentation; Telemetry - methods; Transceivers; Transmitters; wireless telemetry
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2006.889768

State-of-the-art endoscopy systems require electronics allowing for real-time, bidirectional data transfer. Proposed are 2.4-GHz low-power transceiver analog front-end circuits for bidirectional high data rate wireless telemetry in medical endoscopy applications. The prototype integrates a low-IF receiver analog front-end [low noise amplifier (LNA), double balanced down-converter, bandpass-filtered automatic gain controlled (AGC) loop and amplitude-shift keying (ASK) demodulator], and a direct up-conversion transmitter analog front-end [20-MHz IF phase-locked loop (PLL) with well-defined amplitude control circuit, ASK modulator, up-converter, and power amplifier] on a single chip together with an internal radio frequency oscillator and local oscillating (LO) buffers. Design tradeoffs have been made over the boundaries of the different building blocks to optimize the overall system performance. All building blocks feature circuit topologies that enable comfortable operation at low power consumption. The circuits have been implemented in a 0.25-mum CMOS process. The measured sensitivity of the receiver analog front-end is -70 dBm with a data rate of 256 kbps, and the measured output power of the transmitter analog front-end could achieve -23 dBm with a data rate of 1 Mbps. The integrated circuit consumes a current of 6 mA in receiver mode and 5.6 mA in transmitter mode with a power supply of 2.5 V. This paper shows the feasibility of achieving the analog performance required by the wireless endoscopy capsule system in 0.25 mum CMOS.