A 2.4-GHz RF sampling receiver front-end in 0.18-μm CMOS

This paper presents an integrable RF sampling receiver front-end architecture, based on a switched-capacitor (SC) RF sampling downconversion (RFSD) filter, for WLAN applications in a 2.4-GHz band. The RFSD filter test chip is fabricated in a 0.18-μm CMOS technology and the measurement results show a successful realization of RF sampling, quadrature downconversion, tunable anti-alias filtering, downconversion to baseband, and decimation of the sampling rate. By changing the input sampling rate, the RFSD filter can be tuned to different RF channels. A maximum input sampling rate of 1072 MS/s has been achieved. A single-phase clock is used for the quadrature downconversion and the bandpass operation is realized by a 23-tap FIR filter. The RFSD filter has an IIP₃ of +5.5 dBm, a gain of -1 dB, and more than 17 dB rejection of alias bands. The measured image rejection is 59 dB and the sampling clock jitter is 0.64 ps. The test chip consumes 47 mW in the analog part and 40 mW in the digital part. It occupies an area of 1 mm².