Dynamic current supply
AssigneeRCA Corporation
InventorOtto Heinrich Schade, Jr.
Life of this patent
Estimating the term…
Abstract
A dynamic current supply is connected between the emitter electrode of an output transistor and a point of reference potential, to progressively increase the magnitude of the flow of current therebetween, as the output signal at the emitter electrode approaches the point of reference potential. The dynamic current supply includes a current mirror, the output of which is in the path of and controls the flow of current. An MOS transistor, the conductivity of which is a function of the difference in potential between the operating voltage supplied to the output transistor and the output signal, supplies the input or control current to the current mirror.
Claims20
In combination:
- a power terminal for receiving an operating voltage;
- a reference terminal for receiving a reference voltage;
- an input terminal;
- an output terminal;
- an output transistor having a collector electrode connected to said power terminal, a base electrode coupled to said input terminal, and an emitter electrode connected to said output terminal;
- a controlled-current-supply transistor having a principal conduction path between a first electrode thereof and a second electrode thereof, the conductivity of said path being directly related to the potential between said first electrode and a third electrode of said controlled-current-supply transistor, the first and second electrodes of said controlled-current-supply transistor being connected respectively to said reference terminal and to said output terminal;
- and
- means for sensing the potential appearing at said output terminal to generate a control signal applied between the first and third electrodes of said controlled-current-supply transistor to increase its conduction as the potential between said reference terminal and said output terminal decreases in value.
An amplifier comprising, in combination:
- first and second terminals for an operating voltage source;
- a transistor having base, emitter and collector electrodes, connected at its collector electrode to the first of said terminals;
- controllable impedance means coupling said emitter electrode to said second terminal, further including means responsive to the voltage at said emitter electrode, when it approaches the voltage at said second terminal, for reducing the impedance of said controllable impedance means between said emitter electrode and said second terminal to a value such that the voltage between said two terminals reduces to lower than 1V.sub.be, 1V.sub.be being the voltage between the base and emitter electrodes of a transistor which is necessary to support conduction through the transistor.
An amplifier comprising, in combination:
- first and second terminals between which an operating voltage may be applied;
- a signal input terminal;
- a signal output terminal;
- an output transistor having a collector electrode connected to said first terminal, a base electrode coupled to said input terminal, and an emitter electrode connected to said output terminal;
- solid-state means having a current path connected between said emitter electrode and said second terminal, and a control electrode receptive of a control signal for controlling the impedance of said current path;
- and
- means coupled to said output terminal, to said second terminal, and to said control electrode, responsive to an output signal at said output terminal, for applying a control signal to said control electrode, for reducing the impedance of said current path, as the output signal amplitude approaches the voltage level at said second terminal.
Dependencies are inferred from the claim text.