A Micropower Chopper-Stabilized Operational Amplifier Using a SC Notch Filter With Synchronous Integration Inside the Continuous-Time Signal Path

Author

Burt, Rod ; Zhang, Joy

Author_Institution

Texas Instruments Inc., Tucson, AZ

Volume

41

Issue

12

fYear

2006

Firstpage

2729

Lastpage

2736

Abstract

A micropower chopper stabilized opamp is presented. The new topology incorporates a switched capacitor filter with synchronous integration inside the continuous time signal path virtually eliminating chopping noise. A three-stage amplifier with multipath nested Miller compensation is modified to incorporate chopping of the input stage, sinc filtering to notch any chopping ripple, and a compensation scheme to maintain an undistorted high-speed signal path. Characteristics of the amplifier presented include rail to rail input and output operating on supplies of 1.8 to 5.5 V over -40degC to 125degC. Quiescent supply current is 17 muA, input offset is 3 muV, input offset drift is 0.02 muV/degC, GBW is 350 kHz, and the chopping frequency is 125 kHz. Die area is 0.7 mm² using a precision analog mixed-signal CMOS process combining low-noise 0.6-mum analog transistors with 0.3-mum digital CMOS capability

Keywords

CMOS analogue integrated circuits; choppers (circuits); compensation; mixed analogue-digital integrated circuits; notch filters; operational amplifiers; switched capacitor filters; -40 to 125 C; 0.3 micron; 0.6 micron; 1.8 to 5.5 V; 125 kHz; 17 muA; 350 kHz; CMOS analog integrated circuits; SC notch filter; analog mixed-signal CMOS process; chopping noise; chopping ripple; continuous-time signal path; digital CMOS capability; low-noise analog transistors; micropower chopper-stabilized operational amplifier; multipath nested Miller compensation; switched capacitor filter; synchronous integration; three-stage amplifier; CMOS process; Capacitors; Choppers; Current supplies; Filtering; Filters; Operational amplifiers; Rail to rail amplifiers; Rail to rail inputs; Topology; CMOS analog integrated circuits; Choppers; operational amplifiers;

fLanguage

English

Journal_Title

Solid-State Circuits, IEEE Journal of

Publisher

ieee

ISSN

0018-9200

Type

jour

DOI

10.1109/JSSC.2006.884195

Filename

4014603