Monolithic 8x8 SiPM with 4-bit Current-Mode Flash ADC with Tunable Dynamic Range

A monolithic photon-counting receiver consisting of an integrated silicon-photomultiplier and a current-mode analog-to-digital converter (ADC) was designed, simulated and fabricated in the AMS 0.35 mu m SiGe BiCMOS process. The silicon photomultiplier (SiPM) consists of 64 avalanche photodiodes (APD) arranged in an 8x8 pattern with integrated 236 k Omega quenching resistors. This silicon-photomultiplier exhibits peak responsivity at 490 nm and is intended for atmospheric and oceanographic light detection and ranging (LIDAR) applications. The current-mode ADC is used to directly convert photocurrent from the silicon-photomultiplier into a 4-bit word. The maximum sampling rate achieved in simulation is 100 MS/s. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) for the ADC are 0.5 LSB and 0.17 LSB respectively. The dynamic range of the ADC is tunable based on the reference current and varies from 5 mu A - 80 mu A to 30 mu A - 480 mu A. The whole system covers an area of 0.375 mm(2). The fill factor of the silicon photomultiplier is 12.6 %.