Hello sir,I am having difficulty in Calibrate AD59333 evaluation board? Please guide me sir.

Hello sir,I am in my BTech final year.I  am doing my project on accurate  capacitance measuremt.I have Ad5933 evaluation board ,but I unable to calibrate it.Please help me Calibrate the device

  • I unable to calibrate it

    Could you be more specific, unable in what sense?

    The calibration procedure is explained in the manual, beginning on page 18. The easiest way to start is with the resistors: program in frequencies of interest, number of settling cycles > 0, gain = x1,  Excitation = 2Vp-p , resistor only, type in the value of your calibration resistor (it should preferably be about the same as the feedback resistor R2), you may try leaving everything else default. Connect your calibration resistor between Vin and Vout connectors and push Calculate Gain Factor button. Replace your calibration resistor with unknown resistor and push Start Sweep button. the software should show you the unknown resistor values measured at frequency points specified in your sweep settings. The values should be reasonably accurate for the unknown resistors higher in value than your calibration resistor.

    It is also worth reviewing the calibration description in the datasheet beginning p.17 and in https://www.analog.com/media/en/technical-documentation/application-notes/AN-1252.pdf beginning p.5.

  • sir , the calibrated value of the unknown resistor  is coming same as the value of the feedback resistor in the impedance excel sheet?

  • How do we know that the sweep has been completed if we opt for continuous sweep?

  • the calibrated value of the unknown resistor

    Not sure how to interpret this... The only parameter to be calibrated is the system gain. What is the "impedance excel sheet"?

    There is a calibration resistor of a known value, which has to be connected to the system, the system output value has to be recorded and from the system output and the known value of the calibration resistor the system gain is calculated. Then the unknown resistor is connected to the system, the system output value is recorded and form the system output and system gain the unknown resistor value is calculated.

    Calibration and measurement steps are:
    1. Connecting known calibration resistor Rcal between J3 and J4, measuring complex output (re and im) Out = Gain / Rcal.
    2. Calculating complex system Gain by multiplying the complex output value Out by the resistor value Rcal: Gain = Out * Rcal
    3. Attaching unknown impedance Zx and measuring complex output Outx = Gain / Zx
    4. Dividing complex gain from step #2 by Outx from step #3, which yields the unknown complex impedance Zx: Zx = Gain / Outx.

    If the chip settings programmed in are Vexc = 2V p-p and PGA gain = 1x the calibration resistor Rcal value should be about equal to Rfb and with that calibration the chip will be able to measure unknown impedances of a value equal or higher than Rfb. 

  • Since you mentioned you had the evaluation board, you probably have the demo software that came with it. In the same  manual mentioned early, on page 6 there is a chapter "PERFORMING A FREQUENCY SWEEP."

    The sweep is not continuous in a sense that it is never-ending, on the contrary "sweep" implies an action of a certain, usually predefined, duration or magnitude. Like when somebody is sweeping the floor, it is expected that it is done in repetitive, similar strokes. Frequency sweep usually means that  a certain number of different frequencies is going to be generated and/or measured sequentially within a sweep, without any intervention form the operator in between, hence the word "continuous." The operator sets up the parameters of the sweep and lets the system to perform it on its own, so the manual says: "To setup a typical sweep ... use the following steps:"