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Tadashi TAKAGI Mitsuru MOCHIZUKI Yukinobu TARUI Yasushi ITOH Seiichi TSUJI Yasuo MITSUI
A novel nonlinear analysis method of high power amplifier instability has been developed. This analysis method deals with a loop oscillation in a closed loop circuit and presents the conditions for oscillation under large-signal operation by taking account of mixing effect of FETs. Applying this analysis to the high power amplifier instability that an output power for the fundamental wave (f0-wave) decreases at some compression point where a half of the fundamental wave (f0/2-wave) is observed, it has been found that this instability is caused by an f0/2 loop oscillation. In addition, it has been verified by analysis and experiment that the oscillation can be removed by employing an isolation resistor in a closed loop circuit.
Mitsuru MOCHIZUKI Yasushi ITOH Masatoshi NII Tadashi TAKAGI Yasuo MITSUI
A wideband monolithic lossy match power amplifier having an LPF/HPF-combined interstage network has been developed. As an interstage network, it employs an LPF (Low-Pass Filter) including FET's drain capacitance, an HPF (High-Pass Filter) comprised of a dc blocking capacitor and a drain bias circuit, and a constant-resistance network for wideband impedance matching and transformation. With the use of this interstage network, a wide bandwidth of 6 to 16.5 GHz and an output power of 30.40.9 dBm have been achieved.