8-channel CMOS preamplifier and shaper with adjustable peaking time and automatic pole-zero cancellation

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 1998-05, Vol.409 (1-3), p.328-331
• Main Authors: Chase, R.L., Hrisoho, A., Richer, J.-P.
• Format: Article
• Language: English
• Subjects: Instrumentation and Detectors; Physics; ■
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/S0168-9002(97)01291-6

An 8-channel preamplifier-shaper circuit for use with detectors having a capacitance in the range 20–50pF has been designed in 1.2μ CMOS AMS technology. The shaper is designed so that the peaking time can be adjusted, by steps, in the range 200ns–2μs by simple digital control. The pole-zero cancellation circuit uses an original method of sensing the preamplifier feedback capacitor discharging current and producing an identical current to discharge the capacitance of the pole-zero cancellation circuit. The series noise resistance rs=415Ω has been measured (270Ω of which is the protection resistor). The input capacitance of the preamplifier is 10pF + the strays of the test box 10pF for a total of 20pF. The input PMOS transistor has a gm of 5mA/V (from simulation) at 210μA drain current. The cross-talk between channels is less than 1%.