My SURF week-1 work...
Motivation:
To measure the transimpedence of the Broadband photodiode (D1002969-v8), using a New focus photodiode (1611) as reference. The amplitude modulated Jenne Laser (1.2mW) was used.
The steps involved in getting the transimpedence are as follows:
Acquiring data
- Get 2 sets of data from Network Analyzer Agilent 4395: One set of data will be for the transfer function of Ref PD over RF out. The other set for Test PD over Ref PD.
- The following conditions were set:
1) Frequency sweep range: 1MHz to 200 MHz.
2) Number of Points sampled in the range: 201
3) Type of sweep: Logarithmic
- Set the NA to give the corresponding transfer function values in dB and also Phase response in degrees.
- Save the data into floppy disk for processing on the computer (The wireless way of acquiring data was not working when the experiment was conducted )
Plotting
- The matlab code attached (TransimpedencePlot.m) will then give plots for the absolute values of transimpedence in V/A.
- Logic involved in the code:
- Transimpedence = Voltage response / (Responsivity of the photodiode * Power incident)
- Responsivity for BBPD is taken as 0.1 A/W and for NF1611 as 0.68 A/W as given in their datasheets.
- Voltage response of Test PD w.r.t RF output of NA (in dB) = Voltage response of Test PD w.r.t Ref PD (in dB) + Voltage response of Ref PD w.r.t RF output of NA (in dB)
Results
The Plots of transimpedence obtained are attached (results.pdf) . The results obtained for BBPD is consistent with the ones obtained before, but the same method and code gives a different transimpedence for 1611.
The transimpedence of NF 1611 was obtained to be around 4-5 V/A which is very much off-track compared to the one given in the datasheet (elog: 2906).
The transimpedence of Broadband photodiode (D1002969-v8) was around 1200 - 1300 V/A for most of the range, but the value started falling as the frequency approached 100 MHz. This result is consistent with DCC document: T1100467-v2.
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