Hello,
I need to develop a "low cost" and small size strain gauge amplifier. I will need something close to 13 bits effective bits on a 1.5mV range and 10Hz frequency BW. The board will be used with a full bridge and will be placed close to the bridge. I have a few ideas in mind and need sugestions.
From the amp circuit to the processing board there will be a maximum of 2m. In order to prevent values mismatches and noise i am planing to convert the sampled data into PWM to transmit the information and the data would be coded at the duty cycle of the pwm. The advantages of this transmission is that it is imune to frequency mismatches/drift and general noise, however it is susceptible to fast transient glitches. Any comment on that idea?
Regarding the amplication circuit itself. I will be using sigma-delta ADC and i have a few options. To use an MSP430F2013 with internal 16 bits SIgma Delta and an external cheap INA like the microchip MCP6N11 with a gain of 100. The other would be to use a MSP430 with internal 24Bits Sigma Delta and finally the last to use any cheap MSP430 with external Sigma Delta ADC.
Any sugestions and comments?
Regards,
Luis Filipe Rossi