A C-band injection-locked balanced oscillator for direct-conversion QPSK modulation applications
✍ Scribed by Guangjun Wen; Fuzhen Xie; Zhongxiang Shen; Choilook Law; Jiayin Li; Peng Ge
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 110 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0895-2477
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✦ Synopsis
Abstract
A novel quadrature phase shift keying (QPSK) modulation method for RF signal is proposed in this paper. An injection‐locked balanced oscillator (ILBO) operating in the 5.8‐GHz ISM band is developed to demonstrate the approach using a hybrid integrated microwave‐circuit technique. The developed ILBO shows a free‐running performance with anti‐phase outputs of −0.33 dBm at 5.8 GHz under dc bias of 1.183 V and 7.2 mA, total DC‐to‐RF efficiency of 21.8%, and phase noise of −114.85 dBc/Hz at 100‐kHz offset. In the locked state by a 5.8‐GHz injection signal of −23.0 dBm, the device achieved a locking bandwidth of 39 MHz from 5.7806–5.8196 GHz with a 22.5‐dB locking gain, and acquired an output signal phase variation of up to 178° by altering the bias. Four different phase‐state RF signals were obtained from the ILBO by combining the injection‐locking phase‐modulation scheme with a balanced oscillator topology of anti‐phase outputs. As a consequence, the ILBO with a single‐polar double‐throw switch can function as a direct‐conversion QPSK modulator by modulating both the oscillator and switch bias. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 378–381, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11065