A low cross-talk 3-channel analog multiplexer with a 12-bit 25-MS/s pipelined ADC

A full integrated electronics readout presents many challenges for low power and mixed signal design. The analog to digital converter is a critical stage for the system going from the very front-end stages to digital memories. We present here a 12 bit 25MSPS converter designed to multiplex 3 analog channels through one analog to digital converter. It is a first step easy to extend to a next version capable to multiplexed 64 channels through one pipeline ADC. This design makes the assumption that for multi-channel integrated readout electronics, a high speed converter with an input multiplexer helps to improve the equivalent power dissipation related to each channel. A CMOS low cost 0.35µm process is used. The dynamic range is 2V over a 3.3V power supply, and the total power dissipation at 25 MHz is approximately 50mW. The crosstalk measured is close to the noise level.