Original question:
Hello,
may I use a gain amplifier to increase sensor excitation voltage.
if yes, when i increase the voltage, is measurement more precisely.
Hello,
my main problem is that;
The measurement value is proportional with capacitor value. why i cant measure right value in single ended mode.
If i double excitation current may i read capacitor value more precisely.
Hello;
I do more test. I wait for your reply.
I use FDC2112 to measure capacitor with single ended mode. I read data from fdc and calculate frequency value. Also I measure frequency value with scope.
The frequency value is equal to each other. But when I convert to capacitor to frequency value, the cap value is wrong.
I use 22pF, 33pF, 47pF and 100pF ceramic capacitor for this test. In adition I measure this capacitor with LCR meter to lear exact value.
As you see all value is up. But calculated value with FDC data is wrong. You may see an scope screen below.
When I use to calculate above formula all result is wrong. It looks like tank capacitor change with frequency.
Please help.
Best Regards.
