Highly linear dual capacitive feedback LNA for L-band atmospheric radars

Abstract

This paper presents the design of ultra-low noise amplifier (LNA) with dual capacitive shunt feedback in conjunction with source degenerated inductance methodology to simultaneously improve gain, noise figure (NF), and linearity. Addition of two feedback capacitors from drain to gate of the two transistors will relieve the trade-off between NF and linearity and the cascode design will increase the gain. To demonstrate this methodology, a single stage LNA is designed for UHF atmospheric radar application at 1.3 GHz and pHEMT technology is used for the design of LNA and fabricated on low-loss dielectric substrate. Measured results show that LNA has a gain of 24.1 dB and a very low NF of 0.38 dB. The input and output return losses are less than 11 dB and the third-order input intercept point is 48 dBm.

Keywords:

• Atmospheric radar
• capacitive shunt feedback
• low noise amplifier
• noise figure
• third-order input intercept point (IIP3)

Acknowledgments

The authors would like to thank Siddaganga Institute of Technology, Tumkur, India-572103. The authors are also thankful to Modelithics, Inc. as Modelithics models utilized under the University License Program from Modelithics, Inc, Tampa, FL.