LC resonant circuits based matching networks for continuous mode MMIC power amplifiers

Abstract

This article presents a practical design methodology to construct output matching networks for broadband continuous mode monolithic microwave integrated circuit (MMIC) power amplifiers (PAs). Unlike conventional harmonic manipulation approaches, combinations of parallel and series LC resonant circuits are utilized to build the matching networks as it can generate frequencydependent components and locate the varying impedance of continuous mode. With a proper design, the impedance variation in frequency domain can be mapped to the frequency response of the matching network at the fundamental frequency and the second harmonic simultaneously. Matching network design procedures are demonstrated and results show that the frequency response of the network has very good approximation with the desired continuous mode conditions. A prototype PA is implemented on 0.25-μm gallium nitride (GaN) MMIC process, and tested with both continuous-wave and modulated signals. Measurement results show 50.82% maximum drain efficiency and 8.5 dB gain can be achieved across the operation bandwidth of 5.4 to 6.4 GHz.

Design of Broadband Continuous Mode MMIC Power Amplifiers With Bandwidth Improvement

“…Thus, δ becomes the function of frequency, and OMN is expected to provide frequencydependent fundamental reactance X 1 (f ) = −δ(f )R opt and second harmonic reactance X 2 (2f ) = δ(2f )R opt 3π/8. The bandwidth of the constructed OMN depends on how well its frequency response fit the δ variation at both frequencies, which is largely affected by the combination of LC circuits [4]. Poor fitting leads to bandwidth reduction or efficiency degradation in band.…”

“…The operating frequency ranges from 4.5 GHz to 6.5 GHz. The OMN can be constructed with two LC resonant circuits initially using the approach proposed in [4]. Fig.…”

“…In MMIC, the frequency-dependent behaviours of the OMN can be constructed with LC resonant circuits efficiently, since it can not only locate the harmonics but also generate equivalent frequency-dependent components [4]. But the bandwidth of the PA heavily relies on how well the frequency response of the circuits matches the desired impedance requirement.…”