A 370-pJ/b Multichannel BFSK/QPSK Transmitter Using Injection-Locked Fractional-N Synthesizer for Wireless Biotelemetry Devices

• Published in: IEEE journal of solid-state circuits 2017-03, Vol.52 (3), p.867-880
• Main Authors: Teng, Kok-Hin, Heng, Chun-Huat
• Format: Article
• Language: English
• Subjects: Biotelemetry; Broadband; Delays; Delta–sigma; energy efficient; Energy management; fractional; Frequency locking; Frequency shift keying; frequency-shift keying (FSK); injection-locked oscillator; Injection-locked oscillators; low power; Medical devices; Medical equipment; Modulation; multichannel; Multichannel communication; Phase shift keying; Power management; transmitter (TX); Tuning; Wireless communications
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2017.2650407

This paper presents a 401-428-MHz BFSK/QPSK transmitter (TX) with two types of fractional-injection-locking techniques for multichannel transmission capabilities. A ΔΣbased injection-locked ring oscillator is proposed to achieve fine frequency tuning with a frequency resolution of 1.3 kHz. The proposed method facilitates multichannel BFSK modulation. For high data rate wideband QPSK modulation, frequency tuning is achieved through sequential injection locking. The TX performs 550 Kb/s for BFSK and 11 Mb/s for band-shaped QPSK with EVM of 4.4% and 4.9%, respectively. It also achieves a settling time of less than 0.8 μs. This helps to save operating power of the wireless medical devices with duty-cycling protocol employed in the TX. Fabricated in 130-nm process technology, the TX achieves an energy efficiency of 370 pJ/b while delivering -13 dBm of output power with 1-V supply.