Assembled Pomelo (top), as well as its components: detector (bottom), analog board (left), and digital board (right)

I integrated the new SiPM bias supply into the analog board. With this new version (v3) together with the 3cm^3 CsI(Tl) scintillator the results are pretty good:

• 2.6mA @ 3.3V in background conditions
• 4.3mA @ 3.3V with a 44 kBq Na-22 source on the detector
• <10% energy resolution @ 662 keV

The old version (v2) of the board with the same detector had the following:

• 6.3mA @ 3.3V in background conditions
• 7.6mA @ 3.3V with a 44 kBq Na-22 source on the detector
• <10% energy resolution @ 662 keV

Cs-137 and Na-22 spectra taken with the v3 board and 3cm^3 CsI(Tl) scintillator. Threshold was set very high, but it can be set below 60 keV

This updated PCB implements the new low power bias power supply and adds a ramp generator for calibrating the ADC. More details on ADC calibration in a following log.