Linear microwave amplification with Gunn oscillators

• Published in: IEEE transactions on electron devices 1967-09, Vol.14 (9), p.517-522
• Main Author: Thim, H.W.
• Format: Article
• Language: English
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/T-ED.1967.15997

Linear microwave amplifiers with continuous power outputs of 100 mW have been constructed utilizing the frequency-independent negative conductance observed externally in Gunn oscillators. This negative conductance is exhibited only in samples containing propagating dipole layers, in other words, n_{0} . L must be larger than 10 12 cm -2 for n-GaAs. The output power obtainable from this amplifier is substantially larger than that from a subcritically doped GaAs amplifier ( n_{0} . L < 10^{12} cm -2 ) because n_{0} . L can be increased. Power output and efficiency are discussed in terms of n 0 and L . The upper-frequency limit for amplification is determined by the time the domain takes to readjust itself after a change of external voltage which leads to an upper limit for the f. L product (about 10 8 cm/s). The essential feature of the amplifier circuit is to provide both a short circuit at the Gunn oscillation frequency and a broadband circuit at the signal frequency. An average gain of 3 dB was exhibited from 5.5 GHz to 6.5 GHz. Gain compression of 1 dB occurred at 60 mW output power with 9 dB gain, while the noise figure was about 19 dB.