## Outline * Misunderstand: ~~3 times amplitude~~ -> Amplitude is the same to previous board * Grounding noise is caused by CF ## Old board * Grounding noise generated due to w/o CF * ![](https://i.imgur.com/3PMHeHs.png) * 2.1Vpp, 1Hz * **BW < 1Hz** from old board | w/ CF 10pF | w/o CF | | ------ | ------ | | ![1hz-wcf](https://hackmd.io/_uploads/BkpAEYZk0.png) | ![1hz-wocf](https://hackmd.io/_uploads/SkHRNFbJA.png) | | Grounding noise - - | Grounding noise++ | | BW - - | BW ++ | * **All the above are applicable to *New board* expect BW** ## New board | | w/ CF 3pF | w/ CF 10pF | |---|-----------|------------| |1Hz| ![3pcf-1hz](https://hackmd.io/_uploads/r11gDFbk0.png) |![10pcf-1hz](https://hackmd.io/_uploads/ByzXUFWJ0.png)| |10Hz| ![3pcf-10hz](https://hackmd.io/_uploads/HkYxwKW1C.png) |![10pcf-10hz](https://hackmd.io/_uploads/r1nQIF-JC.png)| |100Hz| ![3pcf-100hz](https://hackmd.io/_uploads/SyAgwFbkA.png) |![10pcf-100hz](https://hackmd.io/_uploads/rklEUKZ1A.png)| ## Summery * Trying 5pF or 7pF for CFb of new board * Keeping my design(new board) * Don't add buffer for input of ADC * ![](https://i.imgur.com/knStuDd.png) * 27 ohm Rsource and 100pF Csource * Green scintillation fiber * Need to do scan *R* again * Feature: [low lossless of fiber](https://www.kuraray.com/uploads/5a717515df6f5/PR0150_psf01.pdf)