Diode testing

o Purpose of the measurement

- Test Si QPDs (C30845EH) for ISC QPDs Qty 30 (i.e. 120 elements)

- Test InGaAs PDs (C30665GH) for OMC Qty 10 (i.e. 10 elements)

o Measurement Kit

- Inherited from Frank.

- Has relays in it.

- D0 and D1 switches the measurement instrument connected to an element

- D2 and D3 switches the element of the QPDs

- Digital switch summary

d0 d1 0 0 - ln preamp
d0 d1 1 0 - dark c
d0 d1 0 1 - omc preamp
d0 d1 1 1 - impedance

d2 d3 0 0 - A x x x
d2 d3 1 0 - C x o x
d2 d3 0 1 - B o x o
d2 d3 1 1 - D o o o

- The universal board in the box is currently configured for C30845.
  Pin1 - Elem A. Pin3 - B, Pin7 - C, Pin9 - D, Pin 12 - Case&Bias

o Labview interface

- Controls NI-USB-6009 USB DAQ interface and Agilent 82357B USB-GPIB interface

o Dark current measurement

- Borrowed Peter's source meter KEITHLEY 2635A

- For C30845GH the maxmum reverse bias is set to -20V. This drops the voltage of the each element to the bias voltage.

o Spectrum measurement

- The elements are connected to FEMTO LN current amp DLPCA-200.

- Bias voltage is set to +10V. This lifts up the outside of the amplifier input to +10V.

o Impedance measurement

- Agilent 4395A at PSL lab with impedance measurement kit

- For C30845GH the maxmum reverse bias is set to -15V. This drops the voltage of the each element to the bias voltage.

- Calibration: open - unplug the diode from the socket, short - use a piece of resister lead, 50Ohm - a thin metal resister 51Ohm

- Freq range: 30-50MHz where the response of the cables in the setup is mostly flat.

- Labview VI is configured to read the equivalent circuit parameters in the configuration "D" (series LCR).

- Labview fails to read the series resistance. This was solved by first read the equiv circuit param and then read it with Sim F-CHRST.
  F-CHRST does nothing on the parameters so the second request successfully acquires the first ones.