Operational amplifier with programmable gain
AssigneeRCA Corporation
InventorOtto H. Schade, Jr.
Life of this patent
Estimating the term…
Abstract
An operational amplifier includes a differential-input amplifier stage supplying first and second drive currents responsive to input signals applied to its input connections. A first current amplifier exhibiting gain factor G supplies currents to an output terminal responsive to the first drive current, and a second current amplifier exhibiting gain factor H supplies currents to that output terminal responsive to the second drive current. Each of the first and second current amplifiers includes means for switching the value of its respective gain factor G or H between a plurality of values responsive to a control signal, so the gain of the operational amplifier is programmable responsive to the control signal.
Claims24
An amplifying circuit with switchable gain comprising:
- first and second supply terminals for receiving an operating potential therebetween;
- an output terminal;
- differential-input amplifying means receiving operating potential from said first and second supply terminals, having first and second input terminals at which first and second input signals are respectively received, and having first and second output connections from which first and second drive currents are supplied, varying responsive to the difference between said first and second input signals;
- first current amplifying means of a type having an input circuit for receiving said first drive current, having an output circuit connected between said first supply terminal and said output terminal for conducting current -G times as large as said first drive current, where G is a positive number, and responding to a first control signal to determine the value of said positive number G;
- second current amplifying means of a type having an input circuit for receiving said second drive current, having an output circuit connected between said output terminal and said second supply terminal for conducting current H times said second drive current where H is a positive number, and responding to a second control signal to determine the value of said positive number H;
- and
- means for selectively applying said first and second control signals to said first and second current amplifying means, respectively.
Dependencies are inferred from the claim text.