C-Ku Broadband GaN MMIC Low-noise Amplifiers with Less than 2.5-dB Noise Figure Using Frequency-selective Parallel Feedback Circuit

A C-Ku band GaN monolithic microwave integrated-circuit (MMIC) low-noise amplifier (LNA) for a transmitter and receiver module was developed. A frequency-selective parallel feedback circuit is proposed to achieve broadband performance and low noise figure (NF). The circuit makes stabilization possible at an out-of-band frequency and provides favorable NF and gain characteristics in the C-Ku band. It features an inductor, which resonates in series with a drain–source capacitance of the transistor near the maximum operation frequency. A resistor is employed in parallel with the inductor to stabilize the amplifier at the out-of-band high frequency. As a result, a GaN MMIC LNA with an NF of less than 2.5 dB and a practical gain of greater than 17 dB was achieved at a drain voltage of 12 V and a quiescent drain current of 100 mA/mm at 6-18 GHz. The C-Ku band GaN LNA exhibits a world-class low NF.