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This paper presents a noise suppression technique that is based on the feedback topology for wideband low-noise amplifiers. By nulling the signal in the noise feedback loop, the noise suppression and the signal performance like gain, input matching and output linearity can be considered independently. The overhead on power dissipation is small since the extra loop has less linearity concern. To demonstrate its feasibility, a shuntfeedback type LNA with the proposed noise suppression loop is implemented in a 0.18 m CMOS process. The signal bandwidth is 1.3GHz. The voltage gain and noise figure are 14.1dB and 4.8dB respectively. The current consumption is 1.18mA from a 1.3V supply voltage.Index Terms-shunt-amplifiers, wide band, noise suppression.

This work presents a circuit technique for broadband LNA-mixer to improve the noise and distortion performance simultaneously. By introducing an auxiliary feedforward path that carries the LNA noise and third-order intermodulation distortion (IM3) with equal magnitude and opposite phase to mixer output, the overall noise and IM3 are reduced while the signal is enhanced. The power overhead is small compared to the conventional tradeoff between the power consumption and linearity performance. The test circuit using a 0.18 process includes a shunt-feedback LNA and two cross-coupled active mixers. All the circuits consume 7.7 mA from a 1.8 V supply. The signal bandwidth is 2 GHz. At 900MHz the voltage gain and noise figure are 19 dB and 6.2 dB respectively. There is 2.7dB NF and 10.1dB IM3 improvements with only 15% power overhead.

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