Amplifiers – With semiconductor amplifying device – Including push-pull amplifier
Patent
1990-01-25
1991-10-08
Mullins, James B.
Amplifiers
With semiconductor amplifying device
Including push-pull amplifier
330255, 330298, H03F 330
Patent
active
050557971
ABSTRACT:
An automatic bias control for substantially eliminating crossover distortion in power amplifiers. The bias current is measured in terms of a voltage developed across a resistor in series with the output device. This voltage is processed by a bias control function consisting of a summing circuit, a peak minimum detection circuit, a voltage reference and a mixing circuit added to the output stage in a controlled feedback loop. Elements of these circuits include operational amplifiers. The bias control system is compatible with other feedback loops in the amplifier so that transient and drift control are achieved and no instabilities are introduced. The bias control operates in the presence of widely varying high level signals.
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"Power Amplifier (Buffer) with Low Output Impedance and Current Measurement Capability", IBM Technical Disclosure Bulletin, vol. 30, No. 7, Dec. 1987, pp. 95-97.
W. T. Chater, "A 40W All-MOSFET Power Amp", Audio Amateur, summer edition 1988 (released to public by mail Apr. 29, 1988).
Karwoski and Suffern, "Automatic Bias Banishes Crossover Distortion in Class AB Amplifier", Electronic Design News, Feb. 5, 1986.
Memo from Aerospace Corp., Disclaiming Rights to Chater Invention.
Letter from Mr. R. L. Williams Witnessing Chater Inventorship.
Kearns William J.
Mullins James B.
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