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US 4,365,206 AGranted
Differential amplifier
AssigneeU.S. Philips Corporation
InventorKarl H. Rehfeldt
Life of this patent
Estimating the term…
Abstract
A low-pass transfer is effected between the two stages in an asymmetrically driven differential amplifier, which transfer has a negative effect on the high frequencies. The measure embodying the invention provides by means of a further transistor a negative feedback circuit which causes the low-pass filter to be of a low resistance or because of which it need only process low voltages. This greatly improves the transmission for high frequencies.
Claims4
A differential amplifier comprising:
- two transistors connected by means of their emitters, each of said transistors having an emitter resistor connected in series to a current source, the other side of said current source being connected to a ground terminal of a supply source, the bases of said transistors being connected by means of a current supply impedance to the positive terminal of said supply source, the control of said differential amplifier being effected by a signal applied to a base electrode of one of said two transistors;
- a network circuit, a symmetrical output signal being taken from said network circuit which is connected to the collector-branches of said two transistors, and;
- said differential amplifier further comprising a third transistor whose base is connected to the junction point of said emitter resistors of said two transistors, said third transistor being connected between the base branch of at least one of said two differentially connected transistors and the ground terminal of said supply source.
Dependencies are inferred from the claim text.