公开(公告)号：US10250198B2

公开(公告)日：2019-04-02

申请号：US15887199

申请日：2018-02-02

Applicant: Microchip Technology Incorporated

Inventor： Serban Motoroiu ,  Jim Nolan

IPC: H03F1/12 ,  H03F3/45 ,  H03F1/34 ,  H03G1/00

Abstract: A current feed-back instrumentation amplifier (CFIA) comprises a differential pair with degeneration for amplifying small differential voltages in the presence of large common-mode voltages. The CFIA includes input and feedback transconductors and a trimming circuit that trims the back-bias voltages of the transistors in each transconductor. The trimming circuit includes a plurality of selectable resistors disposed in the signal path of the tail current in each transconductor. Each of the plurality of selectable resistors has a switch coupled to it. When a switch is closed, only the resistors up to the respective switch are in the signal path of the bulk-to-source voltage of the differentially paired transistors. The resistor trimming circuit reduces the mismatch between transconductances of the respective differential pair transistors, in turn reducing mismatch of the overall transconductances of the transconductors, and thereby reducing the CFIA's gain error.

公开(公告)号：US20180323762A1

公开(公告)日：2018-11-08

申请号：US15901623

申请日：2018-02-21

Applicant: Microchip Technology Incorporated

Inventor： Serban Motoroiu ,  Jim Nolan

IPC: H03G3/30 ,  H03F3/45 ,  H03F1/26

CPC classification number: H03G3/30 ,  H03F1/26 ,  H03F3/45179 ,  H03F3/45183 ,  H03F3/45659 ,  H03F2200/129 ,  H03F2200/261 ,  H03F2203/45048 ,  H03F2203/45392 ,  H03F2203/45466 ,  H03F2203/45468 ,  H03F2203/45504 ,  H03F2203/45511 ,  H03F2203/45521 ,  H03F2203/45528 ,  H03F2203/45534 ,  H03G1/0023 ,  H03G1/0029

Abstract: A current feed-back instrumentation amplifier (CFIA) comprises a differential pair with degeneration for amplifying small differential voltages in the presence of large common-mode voltages. The CFIA includes input and feedback transconductors and a chopping modulator circuit that continuously swaps tail current sources between the transconductors. This tail current swapping reduces the contribution to the CFIA's gain error caused by random mismatch between the tail currents of the input and feedback transconductors. The modulator circuit operates on a clock cycle to periodically swap the tail current sources. As a result, even if the tail currents are mismatched, on average the tail currents (transconductor gains) will approximately equal out, and the contribution of the tail current difference to the gain error is canceled out.