Strain Gauge Chip Design

Discussion in 'The Projects Forum' started by Denny1234, Nov 23, 2008.

  1. Denny1234

    Thread Starter Member

    Feb 17, 2008
    Hi, I'm having to design a strain gauge using a commercial analogue CMOS process that can detect the strain in a metal sheet.

    Some of the suggested components I have been given on my design program are pmos differential amplifiers, current source and mirror, low pass filter, Instrumentation amplifier - all of which I understand on a simple building block basis - I know what they do on their own if you get what I mean but I just cant see how to put them into a design?

    Anyway I've tried to read up on strain gauges, and so as a result know a lot about the obvious need for a Wheatstone bridge but as far as that (and reading up on DAC's - which I was told I should do to help me) im so blank.

    Is their anywhere I can find similar circuits to help me out and give me an idea? I doubt it will work as im useless at this project :(

    Any help would be appreciated regardless of how small, subtle or obsure it is.

    Thanks for any assistance


    EDIT* I kinda understand a bit more after further reading about the instrumentation amplifier, this could be my output I think. Also from reading more up on current sources I found that they are common in powering resistance strain gauges. If the simulated source resistance appears to be high enough (which I will try to find out about), the output voltage from the strain gauge will be directly proportional to the resistance of the gauge and, therefore, the amount of strain.
    Last edited: Nov 23, 2008
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    These people - - taught me everything about using strain gauges. They describe everything.

    For a quick rundown, the strain gauge bridge usually has a DC excitation of 10 volts. The bridge outputs are applied to an instrumentation amplifier, whose output is then digitized. Those are the building blocks - voltage source, differential amp, and then an A to D converter.