Pixel analog cells prototypes for ATLAS in DMILL technology

In this paper, we describe the circuit we propose for pixel applications. In particular, we present the different parts of the analog cell, which includes a charge pre-amplifier using PJFET, bipolar and MOS transistors. The pre-amplifier incorporates a new DC feedback circuit which eases tunability, enhances stability and makes the pre-amplifier less sensitive to leakage current. The first stage is followed by a low offset bipolar-based comparator, in which special attention has been paid to reducing threshold spread. We also present experimental results on cell-to-cell mismatch and time walk, which are crucial parameters for realizing an accurate and reliable pixel detector.