The new Inverse Class F operation mode for high-efficiency power amplifiers is analyzed. Unlike regular Class F, it requires an open circuit termination at the second harmonic and a small impedance termination at the third harmonic. The Inverse Class F features higher PAE than Class F but requires transistors with higher breakdown voltages. A study performed using the waveform measurement technique in conjunction with the activdpassive load-pull system showed PAE=83% for the Inverse Class F compared to PAE=64% for the Class F. The measured results are in good agreement with the analytical prediction.

No abstract

No abstract

No abstract

The breakdown voltage of a FET stack is limited by the unequally divided voltage drop among the stacked FETs. A novel stack composed of varying periphery FETs is proposed. Uniform voltage distribution, and thus much higher breakdown voltage, can be achieved by carefully designing the periphery of each FET. A FET stack with varying periphery was designed and fabricated. Significant improvement in breakdown voltage was experimentally confirmed. Unlike the approach of inserting feedforward capacitance, the breakdown voltage increase is achieved without isolation degradation.