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US 4,788,461 AGranted
Solid state inductance simulator
OwnerGary K. Snyderinventor
Life of this patent
Estimating the term…
Abstract
An active choke circuit. The circuit can be used in place of a conventional discrete coil to permit a precise marriage of logic functions to analog functions in a telephone powered by the current in a telephone line.
Claims1
An active choke circuit for providing a high AC impedance, regulated DC and low DC voltage drop, said circuit including
- (a) a DC input source;
- (b) a first transistor having a base connected to said DC voltage source and having an emitter and a collector;
- (c) a second transistor having a base connected to said collector of said first transistor and having an emitter and a collector;
- (d) a third transistor having an emitter connected to the collector of said second transistor, having a collector connected to ground, and having a base;
- (e) at least one diode
- (i) connected between the base of said third transistor and the emitter of said second transistor, and
- (ii) also connected to a first resistor, said resistor being connected between ground and the base of said third transistor,
- such that third transistor is biased when current passes through said diode and said resistor;
- (f) a second resistor connected to the emitter of said first transistor and connected to ground;
- (g) a third resistor connected to said emitter of said first transistor and to the collector of said second transistor;
- (h) a capacitor connected between the base and emitter of said second transistor and to said diode;
- the resistance of said first resistor regulating the current bias input to said third transistor,
- said circuit producing a regulated differential current output at the collector of said second transistor and at the emitter of said third transistor,
- said base of said second transistor being biased by current from said second and third resistors flowing through said first transistor to said base of said second transistor,
- said base of said third transistor being biased by current passing through said diode and said first resistor, and
- current taken from said collector of said second transistor flowing through said third transistor.
13 more elements
Dependencies are inferred from the claim text.