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US 4,786,877 AGranted
Amplifier for voltage or current to frequency converter
AssigneeSangamo Weston, Inc.
InventorRobert A. Leydier
Life of this patent
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Abstract
An autozeroing operational amplifier for a voltage or current-to-frequency converter includes a master amplifier and a slave amplifier. The master amplifier uses the voltage across a master capacitor to control the polarization level of an MOS transistor. Changing this level changes the operation of a differential pair connected to a load thereby changing the amplifier's input offset voltage. The slave amplifier, similarly constructed, is connected to periodically refresh the voltage across the master capacitor to compensate for drift and temperature effects.
Claims14
An amplifier comprising:
- a source of reference potential;
- a control transistor having a first electrode coupled to the source of reference potential;
- charge storage means coupled between the reference potential and a control electrode of the control transistor;
- a first load transistor connected to a second electrode of the control transistor and having a control electrode coupled to a second electrode of the first load transistor;
- a second load transistor having a first electrode connected to the reference potential and having a control electrode connected to the control electrode of the first transistor;
- a differential pair of transistors including a fourth transistor having a first electrode coupled to the first load transistor and having a control electrode coupled to an input terminal, and a fifth transistor having a first electrode coupled to a second electrode of the second load transistor and having a control electrode coupled to a second reference potential;
- a current source connected to a second electrode of the fourth transistor and to a second electrode of the fifth transitor for providing current thereto;
- and
- an output terminal connected to the second electrode of the second load transistor.
6 more elements
An amplifier comprising:
- a master amplifier having a first terminal connected to an input node, a second terminal connected to first charge storage means, and a first output terminal;
- a load connected to the first output terminal;
- a master differential pair of transistors connected to the load, the input node, and to the first output terminal;
- control means for controlling the load in response to a potential across the first charge storage means, the control means being connected to the load and to the first charge storage means;
- and
- a slave amplifier having a first terminal connected to the input node, a second terminal connected to second charge storage means, and a second output terminal switchably connectable to one of the first and second charge storage means.
3 more elements
Dependencies are inferred from the claim text.