THE TIMING Turin VFEUFSD Bulletin 18 th Mar

THE TIMING Turin VFE-UFSD Bulletin 18 th Mar 2020 T 32 VLSI The FAST concept ASIC designers: Jonhatan Olave olave@to. infn. it Federico Fausti fausti@to. infn. it 1

What should be the electronics specs for ps time resolution (embedded or discrete)? Do these specs depends on sensor geometry? What is the limitation from power consumption? 2

What should be the electronics specs for ps time resolution? - The electronics (embedded or discrete) must preserve the sensor speed The key is the matching - Simple model (L is not consider in this discussion) Is = Ie + Ic Is: sensor current Ie: electronics current Ic: equivalent cap current - Two possible cases that depends on the matching: What is the values of the sensor time constant? Which one is better for timing? 3

What is the sensor time constant for UFSD? Fourier Transform Current 10 u. A Time Max slope: 22 u. A/ns -0. 6 -0. 15 0 0. 15 • Sensor current approximated formula to f 1 0. 6 In this approx. the maximum slope in @0. 3 and is 24 u. A/ns very similar to the expected one (22 u. A/ns) 4

Current formula calculation • • Time response can be calculated in the Laplace domain by considering the input current into the RC filter Input current in time domain is: , t ∈ [-T/2, T/2] • , t ∈ [0, T] Input in Laplace domain: 5

Current formula calculation • The current that goes to the electronics is given by: 6

The current Ie Current signal that goes into the amplifier Is 7

The current Ic Current signal integrated in Cdet Is 8

Voltage signal at the amplifier input Voltage signal the amplifier input Cdet = 6 p. F Cdet=6 p. F Cdet [p. F] 1 2 3 4 5 6 Rin [ohm] 20, 0 10, 0 6, 7 5, 0 4, 0 3, 3 9

Where can we locate FAST? 10

What are the ideal specs for the electronics? 11