A HIGH-SPEED AND HIGH-PRECISION WINNER-SELECT-OUTPUT (WSO) ASIC

The design and performance characteristics of a 16-channel Winner-Sele ct-Output (WSO) ASIC are presented. The WSO ASIC does a fast compariso n of 16 analog input voltages, outputs the maximum signal, the ''secon d'' maximum (partner) signal, and their addresses. The WSO ASIC chip i s a key component of an analog electronics system being developed for a depth of interaction (DOT) PET detector module. The basic cell of th e WSO ASIC is a ''winner take all'' (WTA) circuit. The precision of th e WSO ASIC is enhanced by using a cascade structure WTA cell. The chip requires a single +5V supply and consumes 35 mW of power. The WSO ASI C is sensitive to voltage differences as small as 10 mV. The propagati on delay of the chip is less than 30 nsec for voltage differences of > 50 mV (typical for proposed application).