Circuit for filtering a power supply for noise sensitive devices
First Claim
1. A circuit for filtering a power supply for noise sensitive devices, comprising:
- a transistor having a base, an emitter, and a collector;
a first resistor to couple said emitter to a first power supply;
a second resistor to couple said collector to a ground;
a third resistor coupled to said base;
an operational amplifier having a positive input, a negative input, and an output, said output coupled to said base to control the impedance of said transistor via said third resistor, said negative input coupled to said emitter, said op amp coupled to a second power supply and said ground to receive power;
a fourth resistor coupled between said first power supply and said positive input;
a fifth resistor coupled between said positive input and said ground; and
,a capacitor coupled between said positive input and said ground such that said op amp controls a shunt current flowing from said first power supply to said ground via said transistor to produce a filtered power output for a noise sensitive device at said emitter.
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Accused Products
Abstract
The present invention comprises an active shunt filter for filtering a power supply for noise sensitive devices. The active shunt filter includes a transistor and an op amp. A first resistor is coupled between the emitter of the transistor and a first power supply. A second resistor is coupled between the collector of the transistor and a ground. A third resistor is coupled between the base of the transistor and the output of the op amp. The output of the op amp controls the impedance of the transistor. The op amp is coupled to receive power from a second power supply. The negative input of the op amp is coupled to the emitter. The positive input of the op amp is coupled to the first power supply via a fourth resistor. A fifth resistor couples the positive input of the op amp to ground. A capacitor is also coupled between the positive input of the op amp and ground. The op amp controls a shunt current flowing from the first power supply to ground via the transistor to produce a filtered power output for a noise sensitive device at the emitter of the transistor.
23 Citations
8 Claims
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1. A circuit for filtering a power supply for noise sensitive devices, comprising:
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a transistor having a base, an emitter, and a collector; a first resistor to couple said emitter to a first power supply; a second resistor to couple said collector to a ground; a third resistor coupled to said base; an operational amplifier having a positive input, a negative input, and an output, said output coupled to said base to control the impedance of said transistor via said third resistor, said negative input coupled to said emitter, said op amp coupled to a second power supply and said ground to receive power; a fourth resistor coupled between said first power supply and said positive input; a fifth resistor coupled between said positive input and said ground; and
,a capacitor coupled between said positive input and said ground such that said op amp controls a shunt current flowing from said first power supply to said ground via said transistor to produce a filtered power output for a noise sensitive device at said emitter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification