Question

What is the purpose of setting the function generator to High Z.

Answer 1

The purpose of setting the function generator to High Z or High Impedance setting is to match the Input and Output voltage waveforms as set by user .

Selecting these high Z mode set up the generator of the type of impedance to expect from the circuit being measured which allows the generator to modify its output so as per user selected waveform

Zckt = impedance of circuit being measured

Zgen = impedance of generator

If Zckt >>Zgen

Then we are required to choose high Z mode ,

So that ,

By Voltage divider rule ,

Vout = Vin * Z ckt / (Zckt + Z gen)

Vout = Vin * Zckt /Zckt = Vin (since Zckt >>Zgen in our case)

So waveform matching is easily done in high Z mode !!