A wideband LNA with dual-feedback for TV tuner

A wideband LNA is the first amplifying stage in TV tuner system. It requires a low noise figure with a sufficient gain and a high linearity such as high IIP2 and IIP3 due to the many adjacent channels. This paper represents the wideband CMOS LNA using a dual feedback for the tuner application, which can suppress the second and the third order distortions with a low noise and a suitable gain. In the dual feedback, the weak negative feedback improves the linearity of the transconductance partially, thereby maintaining the high gain and low noise. The residual distortion and the distortion of the buffer are cancelled by the positive feedback. Consequently, the proposed wideband LNA with the dual feedback improves noise figure and linearity with a high gain. The LNA fabricated in 0.18 µm RF CMOS demonstrates the expected performances.

[1]  Behzad Razavi,et al.  RF Microelectronics , 1997 .

[2]  Bumman Kim,et al.  A modified cascode type low noise amplifier using dual common source transistors , 2002, 2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278).

[3]  Mohamed A. Y. Abdulla,et al.  Distortion Analysis in Analog Integrated Circuits , 2002 .

[4]  Timo Rahkonen,et al.  Distortion in RF power amplifiers , 2003 .

[5]  Piet Wambacq,et al.  Distortion analysis of analog integrated circuits , 1998 .

[6]  Willy Sansen,et al.  Distortion in elementary transistor circuits , 1999 .

[7]  A. Ismail,et al.  A 3 to 10 GHz LNA using a wideband LC-ladder matching network , 2004, 2004 IEEE International Solid-State Circuits Conference (IEEE Cat. No.04CH37519).

[8]  T. Lee,et al.  A 1.5 V, 1.5 GHz CMOS low noise amplifier , 1996 .