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Lock-in amplifier

XinJing

Jun 7, 2017
2
Joined
Jun 7, 2017
Messages
2
The device under test is a resistor and capacitor paralleled. The impedance (the resistor and the capacitor are time varied), the result is gotten from the lock-in amplifier, i.e.
R = √ (X 2 + Y 2 )
Θ=arctan(Y/X)
The input signal is sin(wt+Θsig),
The reference oscillators r X (t)=sin(2?f ref t+ θ ref ) ; r Y (t)=cos(wt+ θ ref )

How are the values of the resistor and the reactance Xc calculated respectively from the above result?
 

XinJing

Jun 7, 2017
2
Joined
Jun 7, 2017
Messages
2
Thanks for your response. I am able only get the total impedance, Z=R-1/Xc i.e. R-1/jwc and the phase from lock-in amplifier. But there are two unknown parameters R and Xc. I have not implemented the test until finish my homework. I have not figured out the second equation.
The paralleled resistor and capacitor are excited by sine signal.
 
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