Amplifiers – With semiconductor amplifying device – Including signal feedback means
Patent
1994-02-09
1995-03-14
Mottola, Steven
Amplifiers
With semiconductor amplifying device
Including signal feedback means
330104, H03F 134
Patent
active
053980042
ABSTRACT:
A wideband low noise amplifier is provided which includes an input for receiving an input signal and an output for providing an amplified output signal which may vary over a wide frequency range while exhibiting minimum noise interference. The amplifier includes a first amplification stage having a first bipolar transistor with a base connected to the input, an emitter coupled to ground and a collector. A second amplification stage is provided which has second and third Darlington-connected bipolar transistors. The second and third transistors each have a base, collector and emitter with the emitter of the second transistor connected to the base of the third transistor. A first feedback path which includes a first feedback resistor is coupled between each of the collectors of the second and third transistors and the base of the second transistor. The collector of the first transistor is also connected to the base of the second transistor. A second feedback path is connected between the emitter of the second transistor and the base of the first transistor. The second feedback path has a second feedback resistor with an impedance selected so as to optimize noise match, provide gain-bandwidth adjustment and DC bias stabilization. In addition, the second feedback path may further include an inductor for providing an inductive reactance component to further optimize the noise match. Alternately, the inductor may be coupled between the input and the base of the first transistor.
REFERENCES:
patent: 3267386 (1966-08-01), Davis et al.
patent: 3899742 (1975-08-01), Yum et al.
patent: 4559501 (1985-12-01), Akutagawa et al.
patent: 4916409 (1990-04-01), Tracy
I. Kipnis, J. F. Kukielka, J. Wholey and C. P. Snapp "Silicon Bipolar Fixed and Variable Gain Amplifier MMICs for Microwave and Lightwave Applications Up to 6 GHz", IEEE 1989 Microwave and Millimeter-Wave Monolithic Circuits Symposium, pp. 101 through 104.
Mottola Steven
TRW Inc.
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