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| A LO Buffer with Tunable I/Q Phase for WLAN |
| Luo Ke-xin①; Luo Rong①; Zheng Ji-hua②; Yang Hua-zhong① |
| ①Dept. of Electronic Engineering, Tsinghua University, Beijing 100084, China; ②RFIC, Beijing 100084, China |
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Abstract This paper presents a Local Osicillator (LO) buffer for WLAN which can tune the I/Q phase of the LO signal in order to calibrate IQ imbalance in direct conversion transceiver. It can tune the phase by means of switching the MOS capacitor array to delay the LO signal. It is implemented in SMIC 0.18μm, the layout of 4.8~6GHz I/Q LO buffer occupies a total die area of 650×550μm2. Post simulation shows that the phase shift of the I or Q LO buffer varies almost linearly from 0° to 8° with the action of 5bit control word, whereas the output power of the LO buffer varies within 0.2 dB.
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Received: 23 February 2006
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2007, Vol. 29 
