The developement of the CAFE-P/CAFE-M bipolar chips for the ATLAS semiconductor tracker

A bipolar chip has been developed to provide the frontend functions of the binary readout architecture used for the silicon strip detectors in the ATLAS Semiconductor Tracker (SCT). This chip consists of 128 channels of low noise amplification and discrimination and provides an interface to a suitable CMOS data processing chip. The chip was successfully fabricated on the Maxim CB-2 process. Preliminary results including channel-to-channel matching, stability, noise, gain, and irradiation tolerence are presented. These results are compared to the previous CAFE-M chip and the ATLAS requirements.