High speed analog memory integrated circuit for Cherenkov telescopes

Abstract

A switched capacitor analog memory circuit for capturing fast signals from Cherenkov telescopes is described. A four channel version of the memory with 128 cells in each channel has been integrated in a 0.8 /spl mu/m complementary metal oxide semiconductor (CMOS) process with poly-to-poly capacitors. The sampling frequency generated on chip is 500 MHz and the readout frequency is 100 kHz. The measured rms cell pedestal variation in a channel after baseline subtraction is less than 10 mV across the full input signal range. The cell-to-cell gain matching is better than 1% rms, and the nonlinearity is less than 1.3% for a 1.5 V input range. The dynamic range of the memory exceeds 8 bits for a 1.5 V input voltage range.