LED Current Source Design of the circuit to

LED Current Source Design of the circuit to provide constant current supply to the LED Calibrate LED with reference to MIP signal value Expand the design to accommodate multiple LEDs connected concurrently

LED Current Source Pulse Generator Differentiator/ Amplifier Current Mirror One or more LEDs can be connected to the current mirror in the future

LED Current Source Pulse generator includes a fast switching logic clock (possibly a 5 -5 -5 timer) and logic gates Output is a square pulse with amplitude of 2 -3 V (low-voltage logic for power conservation)

LED Current Source Differentiator/Amplifier will be designed using a 1 Ghz fast Op-Amp Gain factors will range from 0. 1 to about 3 -4 Only positive (or negative) pulses will be used (controlled by a fast switching diode)

LED Current Source Current mirror will be designed using fast switching matched transistors Current mirrors will be needed particularly in multi-LED design Later on similar mirror will be used in the pre-amplifier design

LED Current Source LED will be calibrated using Hamamatsu PMT and APD, and possibly Si. PM and MRS We are looking into components Low-power concern is due to a possibility of battery - powered operations for portability of the device (single - LED version only)

LED Current Source Tentative schedule: Design and simulations by next Wednesday, also parts ordered by the end of the week Prototype completed as parts become available Calibrations being a subject to availability of the second test stand