APV25 Circuit Details

The APV25 has an $\rm I^2C$ interface to program internal registers, such as analog bias voltages and currents, the operational mode (peak or deconvolution), and internal calibration settings. The intention of bias adjustment is to compensate possible radiation degradation. However, irradiation tests have shown that in fact the effect of radiation at the CMS level on the APV25 chip is almost negligible.

Apart from a ``soft'' reset by applying a 101 sequence at the trigger input, the APV25 has a dedicated input for a reset signal (``hard'' reset), which has the same effect as a power cycle.

Compared to previous versions of the APV chip, the APV25 has a new feature in addition to peak and deconvolution modes. In the multi-peak mode, the three samples which would be used for the deconvolution algorithm are issued untreated as if three consecutive triggers had arrived (which is not possible because of the special symbols shown in tab. , p. ).

Details of the circuit subsystems [49,50,51] will be given in the following sections.