Re: How to measure millivolt drop?

On Sun, 19 Aug 2007 14:40:27 -0700, DAXU@xxxxxxxxxxx wrote:

Hello,

I am doing a project and one of the requirement is to measure
millivolt voltage signal, need 16-bit ADC. The actual input range is
below 100milivolt. If I choose a ADC with input range to 4V,
1LSB=0.06mV. Shall I just measure the input without any voltage
amplifier added in front of the ADC input pin?

Another requirement is another analog measurement, whose input
impedance is over 20MOhm. Can I just use a normal ADC chip connect to
that input without any other circuit? Or I need a very low bias
current OPamp to amplify the input signal, and have the voltage
amplifier's output connected to the ADC input.

Many thanks,

Regards
Jerry

Them thar homework problems are getting difficult ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave
.

Relevant Pages

  • Re: zero - hundred display
    ... non-inverting op amp with non inverting pin ... connected to a voltage divider of 0.05v. ... 10K linear pot acting as the feedback ... fed to an ADC input -- probably the ADC in the PIC. ...
    (sci.electronics.design)
  • Re: re:using pseudo bipolar ADC
    ... This ADC is just a side track that is needed for the whole project. ... Let's assume gyro zero is significant, but you have to get pretty much ... You can start with the idea above of using a voltage ... look for analog switch IC that will switch bipolar voltages ...
    (sci.electronics.basics)
  • Re: Questions on interfacing to current sense transformer
    ... only one ADC, so I'll have to sample serially, but it should be close. ... Voltage waveforms are rather distorted nowadays, ... The result is true power. ...
    (sci.electronics.design)
  • Re: A/D Precision on a budget
    ... passives, yet would like to maximize the performance of those that I *do* ... Using your existing ADC, simply measure the charging curve using one of the resistances in an RC network. ... You can do a lot with relative resistances, but as mentioned getting a stable, accurate, reference voltage is probably the most difficult part. ...
    (sci.electronics.design)
  • Re: how I can connect 89c51serial port to telephone lineto send data?
    ... I try to send vedio from cctv via telephone line I connect the cctv ... camera output to ADC and the output of the ADC to Atmel 89c51 ... from the ring voltage. ... Your only chance is to store up a bunch of video and then send it ...
    (sci.electronics.basics)