Browse Prior Art Database

CIRCUIT WITH IMPROVED COMMON MODE AND POWER SUPPLY REJECTION

IP.com Disclosure Number: IPCOM000009119D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-08
Document File: 2 page(s) / 79K

Publishing Venue

Motorola

Related People

Vladimir Koifman: AUTHOR [+3]

Abstract

The proposal relates a voltage-to-current con- verters with improved common mode and power supply rejection.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

0 M MO-LA

Technical Developments

CIRCUIT WITH IMPROVED COMMON MODE AND POWER SUPPLY REJECTION

by Vladimir Koifman, Yachin Afek and Eliezer Scind

INTRODUCTION

  The proposal relates a voltage-to-current con- verters with improved common mode and power supply rejection.

BACKGROUND

  Voltage-to-current converters (VICs) receive a differential input signal AV and provide a differen- tial output signal AI. For example, VICs are part of continuous-time ADCs, input stages of operational amplifiers, futers, and other devices. VICs should be implemented in modern devices which have small supply voltages such as, for example, 3.6 volts or less.

  For modem applications, there is a need to pro- vide low-voltage circuits which maintain high rejec- tions (both power supply and input common mode rejections) and which can be used in a spike inten- sive mixed-signal environment.

SOLUTION

  Figure 1 illustrates a proposed WC having (a) signal stage 100 with transistors pair lo/20 for trans- ferring a differential input signal AV to a differen- tial output signal A I and (b) compensation portion 200 with transistor pair 30/40 and transistors 50,60, 70 for compensating the common mode influence of the input signal. Portion 200 monitors the input sig-

nal AV and provides compensation signal IS to sig- nal stage 100. In portion 200, IR is a substantially constant current and IM his a measurement current mirrored into IS. IM and IS depend on common mode changes of AV (gate voltages shifting i...