tim's journal

Low noise 24-bit ADCs

I'm currently using a CS5532-BS to measure noise from dry EEG sensors. After some googlin' this afternoon and browsing through datasheets, it dawned on me that there isn't really a straight-forward way of comparing ADCs. It would be nice to have a website where one enters in the frequency range of interest and the voltage range, and then is given a plot of noise spectrum for various ADCs. You could also have a setup where you can add a number of different front-end amplifiers and see the final result. Alternative vendors include Linear Technology and TI. I've seen the LTC240x and the ADS121x mentioned on Google Groups though I'm not sure how up to date that is. The key, of course, is simply to have noise that is below that of your front-end. Having noise much much smaller really doesn't make that much of a difference.

Linear Technology

• LTC2400 4ppm INL, 1.5uV Noise, 200uA, No Latency Delta Sigma ADC, SO-8
• LTC2401 4ppm INL, 3uV Noise, MS-10, No Latency Delta Sigma ADC
• LTC2410 Differential Input, 0.8uV Noise, No Latency Delta Sigma ADC, SSOP-16
• LTC2411 Differential Input, 1.5uV Noise, No Latency Delta Sigma, MSOP-10
• LTC2413, 24-Bit No Latency Delta Sigma ADC with Simultaneous 50Hz/60Hz Rejection
• LTC2415, 24-Bit No Latency Delta Sigma ADC with Differential Input and Differential Reference
• LTC2415-1, 24-Bit No Latency Delta Sigma ADC with Differential Input, 50/60Hz Rejection
• LTC2440, 24-Bit High Speed Differential ADC with Selectable Speed/Resolution