Research And Design Of Broadband Low Noise Amplifier Based On Noise Cancellation

As the key module of multiple-band and multiple standard wireless receiver front-end,the gain and Noise performance of Broadband Low Noise Amplifier(LNA)directly restricts the whole performance of the wireless receiver front-end.However,there are some mutual constraint between the key performances of LNA,such as input matching,noise factor,gain and bandwidth.Broadband noise cancellation structure LNA mentioned in this paper is based on the combination of capacitance cross coupling common-gate(CG)and shunt feedback,it's input matching condition limits the input transconductance value of the MOS transistor.So that,compared to the circuit's gain,the thermal noise produced by MOS transistor is larger,the noise cancellation rate of the circuit is low.It's difficult to satisfy both input match and low noise figure.To solve this problem,based on the noise cancellation structure of the combination of capacitive cross-coupling CG and shunt feedback,a broadband LNA architecture based on noise cancellation and substrate cross-coupling technology is constructed by using the substrate cross-coupling technology.By adopting capacitive cross-coupling on the substrate of input MOS transistor,the transconductance's freedom of input MOS transistor is increased.When the input matching condition is satisfied,the equivalent transconductance of the input stage increases compared to the MOS transistor's transconductance,which increases the cancellation rate in the noise cancellation path and reduces the noise factor of the circuit.The matter of mutual restriction between input matching and noise factor is improved.In order to further improve the noise cancellation rate,based on the noise cancellation structure of the combination of capacitive cross-coupling CG and shunt feedback,a broadband LNA architecture based on noise cancellation and substrate active gm-boosting technology is constructed by using the substrate active gm-boosting technology.The substrate active gmboosting technology makes the input MOS transistor's transconductance and channel thermal noise current relatively decrease,while the circuit satisfies the input matching and maintains a high gain.The high gain of substrate active gm-boosting technology will also increases the noise cancellation rate and reduces the overall noise factor in the noise cancellation path.In this paper,gain,input matching and noise factor of these two structures are analyzed,and these two structures are designed and simulated by TSMC 0.18?m CMOS process based on Cadence platform.Compared with the noise cancellation structure of the combination of capacitive cross-coupling CG and shunt feedback,In the frequency band range of 0.1? 1.06 GHz,the power gain of wideband LNA architecture based on noise cancellation and substrate crosscoupling technology is improved by 0.5d B,and the noise factor is reduced by 0.4d B and 13%.In the frequency band range of 0.1?1.15 GHz,the power gain of the broadband LNA architecture based on noise cancellation and substrate active gm-boosting technology increased by about 0.6d B,and the noise factor decreased by 0.5d B and 16%.The results show that both the substrate cross coupling technology and substrate active gm-boosting technology can effectively improve the noise cancellation rate and alleviate the mutual restriction between the input matching and the noise factor in the original structure.