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Entry  Mon Aug 1 23:26:32 2011, Koji, Update, LSC, REFL33 PD REFL33_schematic_110801_KA.pdfP8011390.JPG
    Reply  Wed Aug 3 02:20:33 2011, Koji, Update, LSC, REFL165 PD REFL165_schematic_110802_KA.pdfP8031393.JPGP8031391.JPG
       Reply  Wed Aug 3 22:22:47 2011, Koji, Update, LSC, REFL165 PD 
          Reply  Fri Aug 5 04:03:16 2011, Koji, Update, LSC, REFL165 PD P8041394.JPGP8041395.JPGREFL165_test_110804_KA.pdf
    Reply  Wed Aug 3 22:31:38 2011, Koji, Update, LSC, REFL33 PD REFL33_test_110801_KA.pdf
Message ID: 5121     Entry time: Fri Aug 5 04:03:16 2011     In reply to: 5112
Author: Koji 
Type: Update 
Category: LSC 
Subject: REFL165 PD 

REFL165 PD was made and tested. The characterization results are in the PDF file.

Resonance at 166.12MHz
Q of 7.3, transimpedance 667Ohm (Series Resistance = Z/Q2 = 2.5Ohm)
shotnoise intercept current = 4.3mA (i.e. current noise of 36pA/rtHz) 

As the circuit pattern had ~10nH level strain inductance, some technique was needed.

  • The diode was pushed in so as to reduce the lengths of the legs as short as possible.
  • The inductor for the resonant circuit has been located as close to the photodiode as possible
  • The other side of the inductor was needed to be bypassed by a large (0.1uF) capacitor, as the original circuit pattern (D1-L5-C33//R22) was too skinny and long.
  • C32 is also moved next to the diode.
  • The path of the photo current circuit was made thicker by Cu tapes.

Now the size of the loop for the resonant circuit is comparable with the size of SOIC-8 opamp.
(Left-Top corner of the photo)

This improved the resonant gain by factor of 8.5dB at the test with TEST INPUT. (Analyzer photo)

There is no tunable component.
The resonant freq was adjusted by a parallel inductance (270nH) to the main inductor (15nH).



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