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Self Biasing Amplifier for Capacitor Balance

IP.com Disclosure Number: IPCOM000240607D
Publication Date: 2015-Feb-12
Document File: 1 page(s) / 595K

Publishing Venue

The IP.com Prior Art Database

Related People

Mark C. Fischer: INVENTOR

Abstract

An integrated differential amplifier circuit compares the voltage across an integrated divider with the voltage on the center tap of a series connected supercapacitor and balances the voltage on the pair using a novel self-biasing technique which minimizes the overhead current in the amplifier. This has the effect of limiting the balancing current to exactly what is required to balance the supercapacitors. When balanced, the amplifier current diminishes to less than a nanoampere.

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E20140100 -- Self Biasing Amplifier for Capacitor Balance

Background:

An integrated differential amplifier circuit compares the voltage across an integrated divider with the voltage on the center tap of a series connected supercapacitor and balances the voltage on the pair using a novel self-biasing technique which minimizes the overhead current in the amplifier. This has the effect of limiting the balancing current to exactly what is required to balance the supercapacitors. When balanced, the amplifier current diminishes to less than a nanoampere.

Description:

A differential pair of N-Channel MOSFET'S is Source-connected to the drains of two other NChannel MOSFET's which are biased by the difference in current between the differential pair. This is accomplished by mirroring the current in each differential transistor and sourcing the current from one side into one of two differencing mirrors while the current from the other side is mirrored and translated to a sink current for the same side of the differencing mirrors. The bias current in the amplifier is thus proportional to the difference in voltage at the amplifier inputs. The amplifier output is achieved by a P- and N-Channel buffer driven by the same difference in current between the positive and negative inputs of the differential pair. This part of the circuit is a simple operational transconductance amplifier plus buffer. By incorporating the divider into the integrated circuit, the net current load on the supercapa...