RF microelectronics
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This paper describes a fully integrated CMOS low-IF mobile-TV RF tuner for Band-III T-DMB/DAB applications. Most of building blocks such as Low Noise Amplifier (LNA), mixers, Variable Gain Amplifiers (VGA), channel filter, Phase Locked Loop (PLL), Voltage Controlled Oscillator (LC-VCO) and even the PLL loop filter are integrated. The gain of LNA can be controlled from -10 dB to +15 dB with 4 steps of gain resolution. This provides a high signal-to-noise ratio and high linearity performance at a certain power level of RF input because the gain of LNA is not changed abruptly from low to high or otherwise. For further improving the linearity we propose the RF VGA exploiting Schmoock's technique and the mixer with current bleeding, which injects directly the charges to the transconductance stage. The sensitivity is -90 dBm and noise figure (NF) of the receiver is 5.2 ∼ 8.5 dB over the whole T-DMB band of 174 ∼ 239 MHz. The measured 3rd order input intercept point (IIP3) is +2.3 dBm. The tuner rejects the image signal over 50 dB. The chip is fabricated in a 0.18um mixed signal CMOS process. The power consumption is 54 mW at 1.8 V supply voltage. The chip area is 3.0 × 2.5 mm2.