A switchable CMOS LNA using capacitor switching

This paper discusses a design of single path low noise amplifier (LNA) architecture with variable capacitor switching, which can switch between standards of GSM 850 MHz and GSM 1.8 GHz. The LNA is designed using Silterra 0.18 μm CMOS technology process. The inductively degenerated cascode low noise amplifier topology has been adopted to develop this switchable LNA architecture. The post-layout simulations of the multi-standard LNA at 850 MHz for the input matching S₁₁ is -12.74 dB, reverse isolation S₁₂ is -55 dB, power gain S₂₁ is 10.67 dB, and output matching S₂₂ is -15.2 dB. On the other hand, the post-layout simulations at 1.8 GHz for the input matching S₁₁ is -6.9 dB, reverse isolation S₁₂ is -43.94 dB, power gain S₂₁ is 14.13 dB, and output matching S₂₂ is -11.36 dB. The noise figure of the multi-standard LNA at 1.8 GHz is 2.64 dB and 850 MHz is 3.92 dB. The total power consumption for both frequencies is 41.6 mW. The die size is 1.65 mm × 1.80 mm.