BBPD update
- The BBPD circuit has been constructed on the aLIGO BBPD board
- It still keeps 200MHz BW with FDD-100 Si PD for the 100V bias.
- The noise spectrum has been cleaned up a lot more. It shows the noise level of the 0.4mA shotnoise between 9-85MHz.
The noise at 160MHz is the noise level of the 1mA shotnoise.
Some of the noise peaks at around 97MHz came from the bias voltage.
What to do next
- Confirmation of the performance with the original aLIGO BB PD configuration.
- Notch filter for 9MHz (for aLIGO).
- Implementation of a power amplifier. (issues: power supply and heat removal) |