1.9 ∼ 2.6GHz tuning range variable gain low-noise amplifier with digital assisted automatic tuning loop

A novel wide tuning range variable gain differential low-noise amplifier (LNA) with digital assisted automatic tuning loop for multi-mode receiver is proposed in this paper. Common gate LNA with cross-coupled capacitor (CCC) and positive feedback is applied for tuning flexibility and high gain, low noise performance. Digital assisted automatic tuning mechanism reuses the output load inductor and capacitor tank to configure an auxiliary oscillator while tuning, and re-configures it back to narrowband LNA, without extra chip area and power consumption. A testchip is fabricated in 0.13μm CMOS. Measurement results show an LNA performance of 8~26dB variable voltage gain, 2dB NF, -5.5dBm IIP3 and S11<;-10dB. The digital assisted automatic frequency tuning range covers 1.9-2.6GHz with 1% tuning error. The circuit consumes 8mA with 1.2V power supply and the core layout size is 0.35mm×0.55mm.