Amplifier circuit having controllable gain
AssigneeRCA Corporation
InventorArthur J. Leidich
Life of this patent
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Abstract
An amplifier circuit, having voltage gain responsive to a control signal, includes a transistor stage having a transistor and a load, and an amplifier stage in cascade connection, and a control transistor connected to the transistor. The control signal varies the collector current of the transistor via the control transistor whereby the voltage gain of the transistor stage correspondingly varies. Degenerative feedback couples the output to the input for stabilizing the quiescent output potential so that the amplifier circuit is susceptible of being direct coupled to subsequent circuits.
Claims21
An amplifier circuit having controllable gain comprising:
- a transistor stage having input and output connections and including load means coupled in its main current-conduction path;
- current conductive means responsive to a control signal, coupled to the main current-conduction path of said transistor stage for conducting a current flow for varying the quiescent main current flow of said transistor stage with respect to the quiescent current flow of said load means;
- amplifing means having an input connection and having an output connection;
- an input terminal and an output terminal;
- means for coupling said input terminal to the input connection of one of said transistor stage and said amplifying means, for coupling the output connection of the other of said transistor stage and said amplifying means to said output terminal, and for coupling the output connection of said one to the input connection of said other;
- and
- means completing a fixed degenerative feedback connection for coupling a predetermined proportion unaffected by said control signal of the potential at said output terminal to said input terminal to control the quiescent operating potential at said output terminal.
An amplifier circuit having controllable gain comprising:
- a transistor stage including load means coupled in its main current-conduction path;
- current conductive means responsive to a control signal, coupled to the main current-conduction path of said transistor stage for conducting a current flow for varying the quiescent main current flow of said transistor stage with respect to the quiescent current flow of said load means;
- amplifying means having an input connection coupled for receiving input signals and having an output connection coupled to said transistor stage;
- and
- means for completing a fixed degenerative feedback connection from said transistor stage to the input connection of said amplifying means for controlling the quiescent operating point of said transistor stage.
Dependencies are inferred from the claim text.