We are experiencing strange cross talk issue while using ADG726 for switching between different analog sensor to the ADC.
- ADG726 operating in differential mode with 0-5V supply.
- Multiple analog sensors are connected between the SxA (working electrode) and SxB (reference electrode).
- The output DA and DB is connected to a pseudo different ADC in ADuCM355 for performing open circuit potential measurements.
- ADC reference input is connected to internal 1.1v, same is applied to the reference electrode (enables to read negative values as well).
- Cycles through each of the sensor input every few millisecond for ADC measurement.
- Only one sensor connected to the ADC at a time
- When only one sensor is connected to the switch (say S1A and S1B) and all the switches are read, we are getting some voltage measurement in the adjacent switches too.
- This voltage appeared in the adjacent pins are are constant or decaying exponentially but random in nature (some measurement is always made and values is lower than the sensor reading)
- If we change the switch from 1 to any other the number of adjacent pins affected varies as well as the amount
- What could be the reason? crosstalk?
- I verified that the switches are being muxed but could it be because i am not latching the outputs?
- Will the reference dc bias have any affect on adjacent pins
Any help is greatly appreciated. Thanks in advance.
Would it be possible to share schematics of the solution? Also could you post any scope plots you have of the signals.
The ADG728 has a crosstalk plot on figure 18 of the datasheet. What are the characteristics of the signal that is being see on the adjacent channels?