Recent content by Chengjun Li

  1. C

    Create and output a waveform Vout=k*(t)^1/2 using Agilent 33250A

    Hi, I want to output a waveform Vout=k*(t)^1/2, k is a constant,t is time in sec. can I achieve this using Agilent 33250A? And how? Thanks.
  2. C

    How to use a Side-Brazed Dual In-Line Ceramic Package

    I have a silicon chip which has a built in capacitor pair. I use a Side-Brazed Dual In-Line Ceramic Package(shown below) to carry the chip. Wire bonding is used to connect the chip and package. http://www.spectrum-semi.com/CSB02810.pdf is the link to the package. I connect the package to an...
  3. C

    Drift issue in capacitance measurement, why?

    Thanks a lot for your reply and your precious time. I am still not clear about several things you mentioned. "use twisted pairs using SiS guard for shield" I am not sure how to do this. Do you mean something like what's shown below?(I know the leads need to be shorten,here I just want to figure...
  4. C

    Drift issue in capacitance measurement, why?

    I actually realized that I connect the SIS terminal to nothing,that may cause some problem, but using the external capacitors, I don't know where the SIS terminal should be connected to. That's why I surrounded the whole setup with a faraday cage in my experiment. I hope this cage can replace...
  5. C

    Drift issue in capacitance measurement, why?

    Thanks for your reply. I will do the test as you suggest and update the result. I think one thing I need to mention is yesterday I did another test with the socket soldered on board through copper wire but without external capacitors. The result is not stable, either. Now I am suspecting...
  6. C

    Drift issue in capacitance measurement, why?

    Thanks for the advisement. The link to the board specs is http://www.actlsi.co.jp/pdf/at1006_manual.pdf#zoom=75 The manual was written by Japanese, they don't have English version. I use Google translate to understand some important information.
  7. C

    Drift issue in capacitance measurement, why?

    Hi everyone, Please be patient allowing me to introduce the problem shortly. I bought an evaluation board from a Japanese company recently. The board is used to measure very small capacitance difference by transfer input capacitance difference to output voltage, the resolution can reach 0.1fF...
  8. C

    Signal drifting/EM signal/Faraday cage/metal box with connector

    Hi, I am using a evaluation board to measure extreme small differential capacitance on the aF scale. I always got a drifting output, although the speed of drift is slow. I think this might due to the influence of environmental EM signal. I want to use a faraday cage to isolate the EM signal...
  9. C

    Where to solder electronic components on PCB in USA?

    Hi, I got a PCB and want to solder some electronic components on it. The components are very small, I want to find someone who can solder them for me. Is there such a company who are doing such business in America? Can anyone has experience telling me what I need to do?
  10. C

    amplifier gain not stable

    Yes, I did exactly like that, I am sorry I forgot to mention that. I do have a return path for the input current. Is there any other reason that could lead to the strange measurement result? I actually did the same thing for another amplifier in this board(LM324N has four op amp and therefore...
  11. C

    amplifier gain not stable

    Thanks very much for your reply. You are correct, the gain is wrong due to my mistake. Actually the R1=R4=1000kohm. I deduce the equation by myself by considering the current is same between V+&V- and Vout & GND.
  12. C

    amplifier gain not stable

    Thanks for your reply. Please allow me to give a little more description. The voltage I want to amplify is the output voltage of a Linear displacement sensor. This sensor has four electrical connections, two for excitation voltage(here I use 5V DC from a power supply), two for signal output...
  13. C

    amplifier gain not stable

    Hi, I found a differential amplifier board which was made several years ago. The gain of this differential amplifier is 213.765, but I made a simple measurement and found that the gain decrease as the input voltage increases. I wonder is this something normal? Does this ampilifer still...
  14. C

    What does this symbol mean

    But why the numbers are negative. I think the last three triangles with x2 in them seem to be amplifier stage.
  15. C

    What does this symbol mean

    Hi, I got a diagram of a capacitance readout chip like shown below. Could anyone please tell me what do those triangles with different numbers inside them mean? Thanks.
See more
Top