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2.0 KiB
2.0 KiB
Beta 2 Front End Rework
Remove the covers on the front end shielding cans, repeat the steps below for each channel.
- Replace "1" with a 220pF 50V COG 0402 Capacitor (GCM1555C1H221FA16D), this will flatten the crossover response and eliminate peaking for square waves under ~100kHz.
- Replace "2" with a 1.2nF 100V C0G 0603 Capacitor (GCM1885C2A122FA16D), this will increase the frequency for which the maximum 100Vpp input voltage rating applies.
- Replace "3" with a 50Ω 0402 Resistor, this will eliminate peaking past 300 MHz in the frequency response
Beta 2 Noise Improvements
In the middle of the board above the fpga module and to the left side of the ADC, locate the buck regulator:
- Replace "1" with a 120@100MHZ 0402 ferrite bead (BLM15PX121SN1D), leaving room on the left side for 3.
- Add a 22uF 25V X5R 0805 capacitor (GRM21BR61E226ME44L) across the input cap in position "2"
- Add a 22uF 25V X5R 0805 capacitor (GRM21BR61E226ME44L) on the left side of "1", in postition "3". Make sure to scrape off the soldermask to make a ground pad for this cap (shown in black)
This should bring the noise to the level shown below:
