How to realise power-saving analog-to-digital conversion for highly accurate measurements
Summary
Figure 1 - A schematic diagram showing a simplified bridge measurement circuit combined with an in-amp and a SAR-ADC. However, due to the high, fixed oversampling rate, a sigma-delta ADC often has a higher power consumption, which translates to a lower lifetime in the case of battery-operated applications. For example, to connect small voltages from a bridge circuit to a sigma-delta ADC with a 2.5V input range, the PGA has to have a gain of 250. In contrast to such slow measurements, sigma-delta ADCs have the strengths of oversampling, while using a much higher internal oscillator frequency than the output rate. Both sigma-delta ADCs in combination with PGAs and SAR-ADCs with an in-amp are suitable for signal conversion in high precision measurement applications.