Ripple filter circuit
First Claim
1. A ripple filter circuit for eliminating ripple, the ripple filter circuit comprising:
- a driving transistor, connected to a power supply line, for supplying output voltage to a driving subject connected to a ground line;
a reference transistor and a dummy load connected in series between the power supply line and the ground line, wherein the reference transistor functions as a replica of the driving transistor, and the dummy load corresponds to load of the driving subject;
a compensation circuit, connected to a gate terminal of the reference transistor, for canceling a characteristic variation in the reference transistor, wherein the compensation circuit provides its output to a gate terminal of the drive transistor via a low pass filter.
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Accused Products
Abstract
A ripple filter circuit for ensuring the driving of a driving subject while efficiently eliminating ripple even when the operational voltage margin is small. A first transistor, which is connected to a power supply voltage line, is connected to a ground line via a load of the driving subject. A second transistor, which has substantially the same characteristics as the first transistor, and a dummy load are arranged between the power supply voltage line and the ground line. An operational amplifier includes an inverting input terminal, connected between the second transistor and the dummy load, and a non-inverting terminal at which the voltage is decreased by a predetermined voltage from the power supply voltage. The operational amplifier also includes an output connected to the gate terminal of the second transistor and to the gate terminal of the first transistor via a lowpass filter.
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Citations
6 Claims
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1. A ripple filter circuit for eliminating ripple, the ripple filter circuit comprising:
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a driving transistor, connected to a power supply line, for supplying output voltage to a driving subject connected to a ground line; a reference transistor and a dummy load connected in series between the power supply line and the ground line, wherein the reference transistor functions as a replica of the driving transistor, and the dummy load corresponds to load of the driving subject; a compensation circuit, connected to a gate terminal of the reference transistor, for canceling a characteristic variation in the reference transistor, wherein the compensation circuit provides its output to a gate terminal of the drive transistor via a low pass filter. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification