A modal analysis of MMIC power amplifier stability

A technique for predicting power amplifier stability is presented. Monolithic microwave integrated circuit (MMIC) power amplifiers use large periphery output devices to meet their output power goals. Bandwidth and impedance matching considerations typically require that the large output device be subdivided into smaller devices and power combined on-chip. This power combining introduces n possible modes of oscillation when n devices are combined. The usual stability analyses only address one mode. The author presents an approach for predicting and stabilizing oscillations for all n modes. Specific cases for n=2, 3 and 4 are discussed. The approach can be implemented using standard small-signal analysis software.<<ETX>>

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