High performance time-to-amplitude converter array

The analysis of extremely weak and fast light signals exploiting the measurement technique of Time-Correlated Single Photon Counting (TCSPC) is increasingly widespread in a large number of fields: from medicine and biology (fluorescence spectroscopy), to telemetry (laser ranging) and communication (quantum cryptography). The core of any TCSPC acquisition chain is the time measurement block: it has to be able to measure time intervals of few hundreds of nanoseconds with picosecond time resolution and very low differential non-linearity. In addition, collecting data from multiple channels simultaneously has recently become essential to employ the TCSPC technique in even more applications. To meet all these constraints we have designed a fully integrated 16-channel time-to-amplitude (TAC) array in 0.35μm Si-Ge BiCMOS technology showing very high performance. Each converter in the array provides a variable full-scale range (from 12.5 to 100ns) very good time resolution (lower than 27ps), extremely low differential non-linearity (better than 0.2% peak-to-peak of the LSB), low and constant power dissipation (less than 30mW) and high counting rate (11MHz).