Design of C-band Low Noise Amplifier with Switch

Low noise amplifier with switch can effectively solve the problem of the high level and the wide dynamic rang of the input signal in communication systems. This paper presents two types of C-band microstrip LNA circuits with switches. Both using two stages of amplifier and microstrip matching networks, one circuit realizes the adjustable gain about -4 dB to 19 dB, a gain deviation about ldB, noise figure less than 1.6 dB and the work bandwidth over 200 MHz; the other realizes the adjustable gain about -6 dB to 29 dB, max input power about 23 dBm, noise figure less than 1.5 dB, the max gain about 29 dB at 5.25 GHz, a gain deviation about ldB and the work bandwidth over 200 MHz. Additionally, comparisons between these two circuits and between the simulated and measured results are also presented.