AM06: the Associative Memory chip for the Fast TracKer in the upgraded ATLAS detector

\abstract{This paper describes the AM06 chip, which is a highly parallel processor for pattern recognition in high energy physics experiments. It contains memory banks that store data organized in 18 bit words; a group of 8 words is called ``pattern''. Each AM06 chip can store up to 2$^{17}$ patterns. The AM06 integrates serializer/deserializer IP blocks at 2 Gbit/s for input/output communication, to avoid routing congestion at the board level. The AM06 is a complex chip. It has been designed in 65 nm CMOS, combining full-custom memory arrays, standard logic cells and IP blocks. It occupies a silicon area of 168 mm$^2$ and contains 421 millions transistors. The AM06 can perform bitwise comparison at a rate of 100 kHz. Thanks to the XORAM cell and to the design optimization, the AM06 consumes about 1 fJ/bit per comparison. The AM06 has been fabricated and successfully tested with a dedicated test system.