Hello. I need to attenuate 5V analog signals down to 3.3V so they can be read into a 3.3V DSP's ADC. It has to be super SUPER accurate since I will be double-integrating the voltage signal with time and any errors will be hugely magnified.
There seems to be no prexisting attenuation ICs so I was looking at precision volttage dividers. But that I need to use large resistances for less power consumption but this causes problems the output impedence to be too high and input impedence to be too low (since they are potentially unknown this is a general purpose signal conditioner board). As a result, I considering at buffering the voltage divider with an op-amp or integrating the voltage divider with an op-amp for superior input resistance (see diagram).
But there are strange little non-idealities about op-amps such as input bias currents, offset voltages, slew rate, as well as another curious parameter called "Minimum Stable Closed-Loop Gain". This last one concerns me because my circuit will have a gain <1 and all the op-amps I have seen are all have minimum stable gains of 1 or higher.
Can anyone shed some light on this minimum stable gain and other op-amp no-idealities? The offset of 1mV on the output (cannot calibrate for it) causes huge errors to build up in my circuit...
There seems to be no prexisting attenuation ICs so I was looking at precision volttage dividers. But that I need to use large resistances for less power consumption but this causes problems the output impedence to be too high and input impedence to be too low (since they are potentially unknown this is a general purpose signal conditioner board). As a result, I considering at buffering the voltage divider with an op-amp or integrating the voltage divider with an op-amp for superior input resistance (see diagram).
But there are strange little non-idealities about op-amps such as input bias currents, offset voltages, slew rate, as well as another curious parameter called "Minimum Stable Closed-Loop Gain". This last one concerns me because my circuit will have a gain <1 and all the op-amps I have seen are all have minimum stable gains of 1 or higher.
Can anyone shed some light on this minimum stable gain and other op-amp no-idealities? The offset of 1mV on the output (cannot calibrate for it) causes huge errors to build up in my circuit...