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US 6,175,276 B1Granted
Indirect emitter-coupling preamplifier for magneto-resistive heads with single-ended feedback
AssigneeNational Semiconductor Corporation
InventorPerry S. Lorenz
Life of this patent
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Abstract
A preamplifier amplifies a differential signal from a magneto-resistive read head. The preamplifier is designed to maximize gain and minimize introduction of noise, while maintaining wide bandwidths and common mode rejection performance. The emitters of the differential amplifier are coupled together by a third transistor and a capacitor.
Claims14
An amplifier comprising:
- a differential stage receiving a feedback signal, including first and second input terminals for receiving an input differential signal, and first and second output terminals for providing a differential output signal indicative of the input differential signal;
- a differential amplifier receiving said differential output signal, and providing a single-ended amplified output signal indicative of said differential output signal;
- and
- a coupling circuit comprising a first transistor and a low pass filter, said low pass filter for receiving said single-ended amplified output signal, filtering said amplified signal, and providing a filtered amplified output signal through said first transistor to said differential stage as said feedback signal.
1 more element
An amplifier comprising:
- a differential stage receiving a feedback signal, including first and second transistors, first and second input terminals each coupled to a control terminal of said first and second transistors respectively for receiving an input differential signal, and first and second output terminals for providing a differential output signal indicative of the input differential signal;
- a differential amplifier receiving said differential output signal, and providing a single-ended amplified output signal indicative of said differential output signal;
- and
- a coupling circuit, receiving said single-ended amplified output signal, and including a low pass filter for filtering said single-ended amplified output signal and a third transistor coupling into said differential stage said filtered single-ended amplified output signal as said feedback signal.
1 more element
Dependencies are inferred from the claim text.