Summary:

I measured the maximum output of the DAC at 1Y4 as well as its power spectrum. The results are as follows (plots below):

• Maximum amplitude of differential output: + 10V.
• Power spectrum has a peak at 64 kHz.

Therefore, the gain of the high-voltage amplification stage on the PZT driver boards do not need to be changed again, as the required output range of 0-100V from the DAC board was realised when the input voltage ranged from -10V to +10 V w.r.t ground. The AI board converts the differential input to a single ended output as required by the driver board.

I will now change some resistors/capacitors on the AI board such that the position of the notches can be moved from 16k and 32k to 64k and 128k.

Procedure:

 Max. amplitude measurement

My previous measurement of the maximum output amplitude of the DAC was flawed as I made the measurement using a single channel of the oscilloscope, which meant that the negative pin of the DAC channel under test was driven to ground. I redid the measurement to avoid this problem. The set up this time was as follows:

• Positive pin of DAC connected to channel 1 of oscilloscope using break out cable and mini-grabber probe
• Negative pin of DAC connected to channel 2 of oscilloscope
• Grounds of channels 1 and 2 connected (I just hooked the mini-grabbers together)
• Measurement mode on oscilloscope set to channel 1 - channel2
• Used excitation points set up earlier to output a 3 Hz sine wave with amplitude of 32000 counts from channel 9 of the DAC. 

The trace on the oscilloscope is shown below;

So with reference to ground, the DAC is capable of supplying voltages in the range [-10V 10V]. This next image shows all three traces: positive and negative pins of DAC w.r.t ground, and the difference between the two.

 Power spectrum measurement

I used the SR785 to make the measurement. The set up was as follows:

• Positive pin of DAC to A-input of SR560
• Negative pin of DAC to B-input of SR560
• A-B output to Channel 1 input A of the SR785
• SR785 configured to power spectrum measurement

Initially, I output no signal to the DAC, and obtained the following power spectrum. The peak at 65.554 kHz is marked.

I then re-did the measurement with a 200 Hz (left) and 2000 Hz(right), 1000 counts amplitude (I had to change the Ch1 input range on the SR785 from -18dBm to -6dBm) sine wave from channel 9 of the DAC, and obtained the following. The peaks at ~64 kHz are marked.

Now that this peak has been verified, I will work on switching out the appropriate resistors/capacitors on the AI board to move the notches from 16k and 32k to 64k and 128k.