Title :
A continuous-time common-mode feedback circuit (CMFB) for high-impedance current-mode applications
Author :
Lah, L. ; Choma, John, Jr. ; Draper, Jeffrey
Author_Institution :
Univ. of Southern California, Los Angeles, CA, USA
fDate :
4/1/2000 12:00:00 AM
Abstract :
A continuous-time common-mode feedback circuit (CMFB) is presented. A two-stage high-gain architecture is used to stabilize and minimize the offset of the common-mode voltage. A long-channel differential-difference amplifier (DDA) input stage enables this CMFB circuit to have a wide input voltage range without a serious linearity problem. A special compensation scheme enables this circuit to be used in high-impedance current-mode systems without a stability problem. This circuit has been implemented within a continuous-time switched-current ΣΔ modulator in a 2 μm CMOS process. It achieves a ±1 V input voltage range with an active area of 100 μm×60 μm and a power dissipation of 270 μW from a single 5 V power supply
Keywords :
CMOS analogue integrated circuits; circuit feedback; compensation; continuous time systems; current-mode circuits; electric impedance; sigma-delta modulation; switched current circuits; 2 micron; 270 muW; 5 V; CMFB circuit; CMOS process; SI sigma-delta modulator; common-mode feedback circuit; compensation scheme; continuous-time circuit; high-impedance current-mode applications; input stage; long-channel differential-difference amplifier; stability; switched-current ΣΔ modulator; two-stage high-gain architecture; wide input voltage range; Circuit noise; Circuit stability; Current mode circuits; Differential amplifiers; Feedback circuits; Impedance; Poles and zeros; Signal processing; Switching circuits; Voltage;
Journal_Title :
Circuits and Systems II: Analog and Digital Signal Processing, IEEE Transactions on
