HPD with external readout INFN Milano Bicocca April 2010 HPD with external readout Claudio Gotti

HPD with external readout A monolithic charge sensitive preamplifier was designed in our labs, exploiting a 90-nm CMOS technology from TSMC. The preamplifier was tailored for the characterization with nanosecond resolution of a diamond detector, giving signals of about 10 kel, with detector capacitance of 1 pF to 5 pF. → Similar to the requirements of an external readout for the upgrade of HPDs

HPD with external readout The approach is the classic opamp-based charge sensitive preamplifier: → the feedback capacitor Cf is 50 fF → the feedback resistor Rf is 250 kOhm

HPD with external readout The opamp has 3 gain stages and is undercompensated for ~ 500 MHz bandwidth at → Cd = 20 Cf = 1 pF → Cd = 100 Cf = 5 pF A control pin allows to choose between the two possibilities. The opamp input capacitance is Ca = 250 fF

HPD with external readout Simulated 10 kel to 50 kel charge response with Cd = 1pF:

HPD with external readout The output can drive 50 ohm terminated cable (although with a slower risetime): Power dissipation Rise Time Without load With 50+50 W load 7 mW 350 ps 700 ps 5 mW 500 ps 800 ps 4 mW 650 ps 1 ns 3 mW 1.1 ns

HPD with external readout Opamp input series noise is less than 1 nV / sqrt(Hz) at high frequency:

HPD with external readout The Equivalent Noise Charge (ENC) is given by: The feedback resistor gives the parallel noise contribution. With a 10 ns shaping time, we expect Source (detector) Capacitance ENC ( t = 10 ns ) ( t = 5 ns ) 0 pF 160 el 116 el 1 pF 180 el 2pF 215 el 230 el 5 pF 350 el 480 el

HPD with external readout Chip layout: (300 um x 250 um – can be reduced)