Design of Active Match SiGe HBT Low Noise Amplifier Employing Noise Cancellation

Based on Jazz 0.35 μm SiGe process,a SiGe HBT low-noise amplifier(LNA) for 2G,3G and WIMAX application is presented.Taking advantage of the characteristics of low input impedance of common base transistor and low output impedance of common collector transistor,active match in input and output is achieved by selecting the structure and bias current of transistors.The chip area with pad is only 0.33 mm×0.31 mm because the large area inductor is not used.Because the noise figure of the common base transistor is higher than that of the common emitter transistor,the adoption of noise cancellation reduces the noise introduced from the common base transistor.In the bandwidth of 0.6-3 GHz,the LNA shows that the gain is 17.8-19.2 dB,gain flatness is ±0.9 dB,the input and output match well,input and output reflections(S₁₁ and S₂₂) are both less than-10 dB,and the LNA is unconditionally stable in the whole band.