INA121: AMPLITUDE PHASE SHIFT

Hi Randy,

What are you trying to do in your design? As the gain changes, the -3dB corner frequency will move as well based on the gain bandwidth of the device. You can expect this to behave like a standard dominant pole system, where the phase will begin to shift a decade before the corner frequency and stop shifting a decade after the corner frequency for a total phase shift of 90 degrees.

the gain will be constant, there are 4 channels that will be acquiring live signals from sensors

the 4 channels have to be perfectly in alignment with each other

amplitude phase shift from varying input amplitude is the biggest issue

also, frequency phase shift(there is a filter) has some effect also

delay input to output has to be very small, and channel to channel has to be virtually perfect timing

selection of higher precision capacitors (npo, etc) has been done

i am looking at a general understanding of minimizing any phase shift due to change in input amplitude

Hi Randy,

it's difficult to say anything useful without knowing any details of your application. Can you show us a schematic? Can you give us any numbers?

Kai

circuit is proprietary , i need info on minimizing input amplitude phase shift, using op-amps, instrument amps etc
i don't need a circuit analysis

Hi Randy,

I'm not sure I understand what you mean by amplitude phase shift, could you please provide an example of the kind of the specification you are looking for? Assuming you operate within the limitations of the device in a linear region, then a change in amplitude should have no impact on the phase of the signal. Are you perhaps referring to distortion? The output of the amplifier can only change so quickly and this is given by the slew rate of the device. If the rate of change of your input signal times the gain of the amplifier exceeds the slew rate then you will begin to see slew induced distortion.