Preliminary Technical Data

EVAL-AD5933EB

Rev. PrC | Page 11 of 32

4

3

2

1B

1A

Figure 14. AD5933 Evaluation Software Main Dialog Box (The Impedance Profile of a 200 kΩ Resistor Is Displayed.)

Choose the external oscillator as the system clock. Select

External Clock

in the System clock section of the front

panel (see Arrow 1B).

Set the output excitation voltage range of the AD5933 at Pin 6

(VOUT) to 2 V p-p (see Arrow 1B). The four possible output

ranges available are 2 V p-p, 1 V p-p, 0.4 V p-p, and 0.2 V p-p

typically.

In the PGA Control section, select the Gain = ×1 option to set

the gain on the receive stage (see Arrow 1B).

Refer to the Calibration Impedance box (see Arrow 1B). Prior

to making any measurements, calibrate the AD5933 with a

known (that is, accurately measured) calibration impedance

connected between the VIN and VOUT pins of the AD5933.

The choice of calibration impedance topology (for example, R1

in series with C1, R1 in parallel with C1, etc.) depends on the

application in question. However, you must ensure that each

component of the measured calibration impedance is entered

correctly into each chosen topology component text box (see

Arrow 1B). For example, in Figure 14 the Resistor only R1

option is selected to measure the impedance of a 200 kΩ

resistive impedance across frequency. For this example, type

200E3

(Ω) into the Resistor Value R1 box.

To program the sweep parameters as chosen above into the

interface, click Program Device Registers (see Arrow 2).

The value programmed into the Number of Settling Time

Cycles

box can be set so that the settling time is multiplied by a

factor of 2 or 4 for a sweep (Arrow 3A). Select the ×1 (Default)

option.

Now that the frequency sweep parameters and gain settings are

programmed, the next step is to calibrate the AD5933 system by

calculating the gain factor.