DocumentCode :
846297
Title :
Intermodulation distortion analysis of class-F and inverse class-F HBT amplifiers
Author :
Ohta, Akira ; Inoue, Akira ; Goto, Seiki ; Ueda, Kazuhiro ; Ishikawa, Takahide ; Matsuda, Yoshio
Author_Institution :
Mitsubishi Electr. Corp., Hyogo, Japan
Volume :
53
Issue :
6
fYear :
2005
fDate :
6/1/2005 12:00:00 AM
Firstpage :
2121
Lastpage :
2128
Abstract :
The third-order intermodulation distortions (IM3s) of class-F and inverse class-F heterojunction bipolar transistor amplifiers were compared experimentally. It was revealed that the IM3 of inverse class F is lower than that of class F at high input power (Pin), although the better class for IM3 at low Pin changes from class F to inverse class F according to the increase of the quiescent current (Iq). The different IM3 behaviors are mainly caused by the different gain variations in both amplifiers. At a low Pin, the gain of class F is larger than that of inverse class F. The larger gain in class F causes a gradual gain decrease and a steep gain rise at high and low Iq, respectively. On the other hand, the gain of inverse class F is larger than that of class F at a high Pin. The larger gain in inverse class F causes a gradual gain decrease at all Iq values. These gradual gain decreases are one of main causes of a lower IM3. These phenomena can be explained by the output current (Iout) and voltage (Vout) waveforms, which differ according to the harmonic loads. The Iout and Vout positive half-sinusoidal waveforms, which consist of in-phase second harmonics, are effective for large-gain operations. The positive half-sinusoidal Iout waveform of the class-F amplifier prevents a gain decrease at a low Pin and high Iq, and the similar Vout waveform in inverse class F prevents a gain decrease at a high Pin.
Keywords :
UHF power amplifiers; code division multiple access; heterojunction bipolar transistors; intermodulation distortion; code division multiple access; half-sinusoidal waveforms; harmonic loads; heterojunction bipolar transistor; in-phase second harmonics; intermodulation distortion analysis; inverse class-F HBT amplifiers; large-gain operations; output current waveforms; output voltage waveforms; power amplifiers; quiescent current; third-order intermodulation distortions; Heterojunction bipolar transistors; Impedance; Intermodulation distortion; Multiaccess communication; Operational amplifiers; Optical amplifiers; Power amplifiers; Power system harmonics; Telephone sets; Voltage; Code division multiple access (CDMA); heterojunction bipolar transistor (HBT); intermodulation distortion; power amplifiers;
fLanguage :
English
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9480
Type :
jour
DOI :
10.1109/TMTT.2005.848769
Filename :
1440732
Link To Document :
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