US PATENT SUBCLASS 330 / 75
SIGNAL FEEDBACK

Current as of: June, 1999
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330 /   HD   AMPLIFIERS

75SIGNAL FEEDBACK {20}
76  DF  .~> Compensating for inter-electrode impedance (e.g., neutralization) {4}
81  DF  .~> At least one push-pull signal stage {2}
84  DF  .~> Plural amplifier channels
85  DF  .~> Amplifier in signal feedback path
86  DF  .~> Variable impedance in feedback path varied by separate control path
87  DF  .~> Cathode impedance feedback {4}
96  DF  .~> Combined with control of bias voltage of signal amplifier
97  DF  .~> Including D.C. path for signal feedback
98  DF  .~> In cascade amplifiers {1}
101  DF  .~> Positive and negative feedback in same path at different frequencies
102  DF  .~> Current and voltage feedback
103  DF  .~> Multiple feedback paths {1}
105  DF  .~> From impedance in series with output load (e.g., current feedback)
106  DF  .~> In series with input source
107  DF  .~> Phase shift means in loop path
108  DF  .~> Potentiometer common to signal and feedback path
109  DF  .~> Frequency responsive feedback means
110  DF  .~> Nonlinear impedance element in loop path
111  DF  .~> To or from an auxiliary grid or to the anode
112  DF  .~> Positive feedback

DEFINITION

Classification: 330/75

(under the class definition) Subject matter wherein signal feedback circuit means are provided to superimpose a portion of the electrical signal output energy on the amplifier input signal.

(1) Note. The above amplifier may be any stage or group of stages of a cascaded amplifier.

(2) Note. The signal feedback of amplifiers classified in this and indented subclasses is distinguished from the type of feedback which may be found in amplifier gain control circuits principally in subclasses 129+ in that the latter involves the development from the signal, of a D.C.. voltage which is filtered and smoothed and then applied to an amplifier electrode to control the bias thereon; whereas in this and indented subclasses the feedback voltage which is applied to the input electrode varies in each instant in the same manner that the signal varies and may be in any phase relationship with the input signal (i.e., in phase, 180 deg. out of phase or any other phase angle relationship).

(3) Note. The term "loop path" as used in some of the indented subclasses refers to the loop formed by the forward signal path from the signal input electrode in the circuit to which the signal feedback is applied to the output and in

addition the signal feedback path from the signal output electrode from which the feedback is derived to the signal input electrode to which the signal feedback is applied.

(4) Note. In feedback amplifiers there is an impedance shared by the input and output circuits which may be a transformer.

SEE OR SEARCH THIS CLASS, SUBCLASS: 291+, for semiconductor amplifiers having signal feedback.

SEE OR SEARCH CLASS

327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems,

590, for miscellaneous circuits with signal feedback.

329, Demodulators,

319, for feedback used in frequency demodulation noise reduction, and subclass 367 for regenerative feedback in an amplitude demodulator.

331, Oscillators, appropriate subclasses, for oscillator circuits utilizing feedback.

364, Electrical Computers and Data Processing Systems, appropriate subclasses for data processing control systems, particularly

130+, for closed loop feedback systems.