A 50-Mb/s CMOS QPSK/O-QPSK transmitter employing injection locking for direct modulation

作者：Diao Shengxi^*; Zheng Yuanjin; Gao Yuan; Cheng San Jeow; Yuan Xiaojun; Je Minkyu; Heng Chun Huat

来源：IEEE Transactions on Microwave Theory and Techniques, 2012, 60(1): 120-130.

DOI：10.1109/TMTT.2011.2174377

• Area savings
• Building blockes
• Capacitor bank switching
• CMOS
• CMOS technology
• Core area
• Direct modulation
• Error vector magnitude
• High-quality imaging
• Injection frequencies
• Injection-locking
• Low Power
• Output power
• QPSK modulation
• Self resonant frequency
• Supply voltages
• Voltage controlled oscillator

A 50-Mb/s quadrature phase-shift keying (QPSK)/offset quadrature phase-shift keying (O-QPSK) transmitter suitable for biomedical high-quality imaging application is presented. Centered at 915 MHz, the phase modulation is achieved by directly modifying the self-resonant frequency of an LC voltage-controlled oscillator through capacitor bank switching. By eliminating many unnecessary building blocks in the conventional QPSK/O-QPSK transmitter, significant power and area savings are achieved. Implemented in 0.18-μm CMOS technology, it occupies an active core area of 0.28 mm2. With 305-MHz injection frequency and consuming 5.6 mW under 1.4-V supply, the transmitter achieves error vector magnitude (EVM) of 11.4%/5.97% for O-QPSK/QPSK modulation while delivering output power of -3 dBm at 50 Mb/s. By lowering the injection frequency to 101.67 MHz, it consumes 5.88 mW under the same supply voltages while delivering an output power of -3.3 dBm. The transmitter achieves measured EVM of 6.4% at 50 Mb/s under QPSK modulation.

• 出版日期2012
• 单位National university of Singapore; the National University of Singapore