Topmetal-II⁻: a direct charge sensor for high energy physics and imaging applications

Topmetal-II⁻, a direct charge sensor, was manufactured in an XFAB 350 nm CMOS process. The Topmetal-II⁻ sensor features a 72 × 72 pixel array with an 83 μm pixel pitch which collects and measures charge directly from the surrounding media. We introduce the implementation of the circuitry in the sensor including an analogue readout channel and a column based digital readout channel. The analogue readout channel allows the access to the full waveform from each pixel through a time-shared multiplexing. The digital readout channel records hits identified by an individually settable threshold in each pixel. Some simulation and preliminary test results are also discussed