Hello everyone,
I need to measure the spectral impedance of different DUTs (Devices Under Test) in sequence, i.e. one after another. So I'm trying to use an analog demultiplexer to switch between the DUTs automatically. The problem is that the measured impedances of the DUTs change when the Demux is connected, i.e. there is a deformation of the resulting signals across the DUTs.
According to the datasheet of the IC (CD4052B) , the ON resistance of the channels is very low in comparison with the impedances of the DUTs, and the cutoff frequencies are far above my measurement frequencies.
Some characteristics of the equipment:
Demultiplexer: CD4052B (DC voltage source: +- 5 V)
LCR-meter: Agilent E4980a
Frequency range: 20 Hz - 100 kHz
Signal amplitude: <= 100 mVrms
Impedance range of the DUTs: 1 kOhm - 1 MOhm
I don't understand the source of the error, but even if it's unavoidable: is there a way to correct/compensate the values? I tried the Open-Short-Load compensation described in page 4-6 of the "Agilent Impedance Measurement Handbook", but the compensation was not satisfactory.
If necessary, I could give quantitative examples.
I need to measure the spectral impedance of different DUTs (Devices Under Test) in sequence, i.e. one after another. So I'm trying to use an analog demultiplexer to switch between the DUTs automatically. The problem is that the measured impedances of the DUTs change when the Demux is connected, i.e. there is a deformation of the resulting signals across the DUTs.
According to the datasheet of the IC (CD4052B) , the ON resistance of the channels is very low in comparison with the impedances of the DUTs, and the cutoff frequencies are far above my measurement frequencies.
Some characteristics of the equipment:
Demultiplexer: CD4052B (DC voltage source: +- 5 V)
LCR-meter: Agilent E4980a
Frequency range: 20 Hz - 100 kHz
Signal amplitude: <= 100 mVrms
Impedance range of the DUTs: 1 kOhm - 1 MOhm
I don't understand the source of the error, but even if it's unavoidable: is there a way to correct/compensate the values? I tried the Open-Short-Load compensation described in page 4-6 of the "Agilent Impedance Measurement Handbook", but the compensation was not satisfactory.
If necessary, I could give quantitative examples.