Project Resources:

https://docs.google.com/document/d/1uMhZbrjy4h7P3S4hgvYHxCAvWjgHozcVUgSRDQH5D5s/edit?usp=sharing

https://docs.google.com/document/d/1O7Zn6XXuKUzf7-EnrcJN0tukMsXGqb2XmS91orYVu7I/edit?usp=sharing
https://docs.google.com/document/d/1rbeQXoqX3_iZjQlVWfSDjXrRMNYCyoMgeSvU2urp8gc/edit

https://docs.google.com/document/d/1LQRfJvyCAvVPx5eveaM_oDLg-V8NaFBstOVcZV9izbM/edit?usp=sharing

Functionality:

Radiation detection:

Scintillator generates light, SiPM generates a current pulse proportional
to the magnitude of radiation.

In order to detect and log that current pulse on an MCU (microcontroller unit) we need a detector circuit to:

1. Convert the current signal to voltage

2. Amplify the voltage pulse to increase difference between signal and noise
   and make it easier to detect and losses negligible. This is done by the detector circuit.

3. Extend the length of the signal so the MCU has time to made an ADC conversion.

Detector Circuit Topology:

1. Transimpdance amplifier converts current signal from SiPM to voltage, amplifies it in a way
   to reduce the signal to noise ratio.

2. Filter stage to eliminate high and low frequency noise

3. Second stage amplification

4. Peak detector to extend signal

5. Voltage follower to ensure signal sampling does not interfere with the peak detector circuit.

Data logging:

After the second stage amplification, the signal line is sent to both the peak detector and a comparator.
The comparator compares the signal to a set baseline voltage value, and if the signal exceeds this amount,
it generates an interrupt. This interrupt is used to tell the MCU when to take an ADC (analog to digital conversion) sample from the
peak detector line.

Voltage supply & Power Management:

Open

Because the detector circuit is sensitive analog circuitry, it runs off a separate 4.7V line
from an LDO. The LDO cleans the 5V line to ensure low-noise, as well as separates the detector
circuit supplies from any noise generated by the switching supplies.

The SiPM requires 36V to operate. This is achieved with a voltage booster paired with an LDO to
make sure the supply voltage is clean.

The detector_support circuit is configured to support both a test connection (5V and 12V from the
bench top supply) as well as battery connections for use in lab testing.

PWR_EN - Signal that allows us to turn on/off the radiation detectors to reduce power usage while sitting on the pad

VERY BASIC OVERVIEW of commonly used voltage supplies:

LDO - Linear regulator, clean but highly inefficient voltage regulator. Can only produce voltages below input. Very simple to implement.

Switching regulator - efficient regulator, noisy, more difficult to implement

System Layout

Open