| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 101 === In recent year, the rapid development of medical electronics improves the quality of medical care. For long-term bio-medical monitoring applications, using implantable or wearable wireless product makes patient more comfortable and mobile. For these applications, a low power, small area wireless transmitters are required. In June 2002, in order to solving interference problem, FCC allocated 14-MHz of radio spectrum to Wireless Medical Telemetry Services. However, no transmitter front-ends circuits using WMTS band has been published.
In this thesis, the design methodology and implementation of a 1.4-GHz RF transmitter front-end for WMTS band are presented. The proposed transmitter which consists of a power amplifier, an IQ modulator and a quadrature voltage-controlled oscillator is designed in 0.18-μm CMOS technology. The proposed power amplifier uses Doherty amplifier architecture. In simulation results, the power amplifier achieves power added efficiency (PAE) of 29% at P1dB and 15% at 6 dB back-off power level. IQ modulator and QVCO with low power consumption of 2.45 mW and 2.26 mW achieve function of up-conversion. In experimental results, it consumes 35 mW under 1.5-V power supply for 5 dBm output power. The efficiency is 9.04%. The conversion gain of whole TX is 20 dB. The image rejection is 20 dBc, and LO rejection is also 20 dBc. The die area is 2.06 mm2.
Finally, discussions about the reasons of degradations of LO rejection and image rejection are made. A modified differential transmitter is proposed. The modified differential Doherty PA achieves PAE of 25% at P1dB and 13% at 6 dB back-off power level. The re-designed TX achieves P1dB of 8 dBm. The conversion gain is 20 dB. The power dissipation is 62 mW under 1.5V power supply, and the efficiency is 10.1%. The image rejection and LO rejection are 52 dBc and 51 dBc, respectively. The die area is 2.59 mm2. The re-designed TX will be implemented in TSMC 0.18-μm CMOS technology.
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