Title :
Harmonic tuning of power FETs at X-band
Author :
Khatibzadeh, M.A. ; Tserng, H.Q.
Author_Institution :
Texas Instrum. Inc., Dallas, TX, USA
Abstract :
A study is presented of high-efficiency, harmonic-tuned, class-B operation of power MESFETs at X-band. Hybrid, single-stage 1200- mu m power FET (field-effect transistor) amplifiers were fabricated with the output circuit designed to provide optimum load impedance at the fundamental frequency (10 GHz) and short at the second harmonic. Power-added efficiency of 61% at an output power level of 450 mW and 7-dB power gain were obtained at 10 GHz. The corresponding drain efficiency was 75%. The second harmonic level in the output was suppressed to less than -40 dBc over a 4% frequency bandwidth. The efficiency was improved at the expense of a lower operating voltage and power density (0.4 W/mm) when compared with class-A or class-AB amplifiers made from similar devices. Theoretical harmonic-balance analyses of these tuned class-B amplifiers were also performed, and the results agree fairly well with the measured data.<>
Keywords :
Schottky gate field effect transistors; microwave amplifiers; power amplifiers; power transistors; solid-state microwave circuits; solid-state microwave devices; tuning; 10 GHz; 1200 micron; 450 mW; 61 percent; 7 dB; X-band; class-B operation; fundamental frequency; harmonic tuning; harmonic-balance analyses; operating voltage; optimum load impedance; output power level; power FET amplifiers; power MESFETs; power added efficiency; power density; power gain; second harmonic level; Bandwidth; Circuit optimization; FETs; Frequency; Impedance; MESFETs; Power amplifiers; Power generation; Power system harmonics; Tuning;
Conference_Titel :
Microwave Symposium Digest, 1990., IEEE MTT-S International
Conference_Location :
Dallas, TX
DOI :
10.1109/MWSYM.1990.99745
