A CMOS “soft-switched” transconductor and its application in gain control and filters

Author

Mensink, Clemens H.J. ; Nauta, Bram ; Wallinga, Hans

Author_Institution

MESA Res. Inst., Twente Univ., Enschede, Netherlands

Volume

32

Issue

7

fYear

1997

fDate

7/1/1997 12:00:00 AM

Firstpage

989

Lastpage

998

Abstract

This paper presents a transconductor suitable for implementation in submicron CMOS technology. The transconductor is nearly insensitive for the second-order effects of the MOS transistors, which become more and more prevalent in today´s submicron processes. The transconductor relies on a differential pair with variable degeneration resistance, while the degeneration resistors are “soft-switched” by means of MOS transistors. The transconductance is continuously tunable. A transconductor, using a device in which the degeneration resistors and “soft switches” are merged, is optimized for a maximum tuning range and can be used in variable gain stages like in an automatic gain control (AGC) circuit. Besides, a third-order 5.5 MHz low-pass filter has been realized in a 0.5-μm CMOS process using the “soft-switched” transconductor. At a 3.3 V supply voltage the filter dissipates 12 mW and the dynamic range equals 62 dB where the total harmonic distortion (THD) is -48 dB for an input voltage of 1 Vpp

Keywords

CMOS analogue integrated circuits; automatic gain control; circuit tuning; continuous time filters; differential amplifiers; harmonic distortion; low-pass filters; 0.5 micron; 12 mW; 3.3 V; 5.5 MHz; CMOS soft-switched transconductor; automatic gain control; continuously tunable; differential pair; dynamic range; input voltage; low-pass filter; maximum tuning range; second-order effects; submicron CMOS technology; total harmonic distortion; variable degeneration resistance; CMOS technology; Circuit optimization; Low pass filters; MOSFETs; Resistors; Switching circuits; Transconductance; Transconductors; Tunable circuits and devices; Voltage;

fLanguage

English

Journal_Title

Solid-State Circuits, IEEE Journal of

Publisher

ieee

ISSN

0018-9200

Type

jour

DOI

10.1109/4.597289

Filename

597289