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US 4,302,726 AGranted
Current sources
AssigneeGeneral Electric Company
InventorDavid E. Shobbrook
Life of this patent
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AssigneeGeneral Electric Company
InventorDavid E. Shobbrook
Estimating the term…
A current source in which the output current from an output amplifier stage (2) is controlled by an input signal, originating in a signal source (11), to an input amplifier stage (1) incorporates, additionally to a negative feedback path from the current input path of the output stage (2) to the input amplifier (1), monitoring means (5) in the signal input path to the output amplifier (2) and control means (4) in an input path to the input amplifier (1). Monitoring means (5) monitors the current flow in the input path to the output amplifier (2) and applies, via control means (4) a signal to the input amplifier (1) such that the dependence of the current flow in the current output path on the gain of the output stage (2) is reduced. A circuit is described, as well as an application to driving a telephone subscriber line and using two current sources working in push-pull mode.
A current source arrangement in which the magnitude of current flowing in an output path of a transistor amplifier stage is arranged to be controlled by an input signal applied to an input of the arrangement, said input signal being applied to the transistor amplifier stage by way of a differential amplifier, comprising means to derive a negative feedback signal whose magnitude is dependent upon that of said current in said output path, means to apply said negative feedback signal to an input of said differential amplifier, means to derive a further feedback signal whose magnitude is dependent upon the value of input current to said transistor amplifier stage, and means to apply said further feedback signal as a positive feedback signal to an input of said differential amplifier whereby to reduce the dependence of the current flowing in said output path on the gain of the transistor amplifier stage.
A current source arrangement comprising a differential amplifier having inverting and non-inverting inputs and an output, and a transistor having an input electrode, an output electrode, and a control electrode, the input electrode being connected by way of a resistive element to one pole of power supply means and the output electrode being connected by way of a load circuit to the other pole of said power supply means, the output of the differential amplifier being electrically coupled to the control electrode of the transistor , means to apply a control signal to one input of the differential amplifier, feedback means to apply to another input of the differential amplifier a first feedback signal dependent upon the voltage developed in operation across said resistive element, means to derive a second feedback signal dependent on the current flow to the control electrode of the transistor, and means to apply said second feedback signal as a positive feedback signal to said one input of the differential amplifier.
Dependencies are inferred from the claim text.