EFFECT OF 1/F NOISE ON THE RESOLUTION OF CMOS ANALOG READOUT SYSTEMS FOR MICROSTRIP AND PIXEL DETECTORS

The noise performance of low-power CMOS analog readout systems for small detector capacitances ranging from 10 fF to 10 pF is analytically studied. Design criteria are given for both charge sensitive amplifiers and semi-Gaussian pulse shapers so as to achieve the theoretical minimal possible ENCs of the systems. The significant effect of I/f noise on the system resolution is determined. It is shown that for low-power readout systems employing a short peaking time (e.g, tau-s < 100 ns), the total system ENC is dominated by the channel thermal noise rather than 1/f noise. Therefore, for these applications, a CMOS approach is preferred to other ones using expensive technologies such as CMOS-JFET [Z.Y. Chang and W. Sansen, Low-Noise Wide-Band Amplifiers in Bipolar and CMOS Technologies (Kluwer, 1990)].