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ada4927-1 adding dc offset onto inverting input to maximize adc range

Question asked by gdownie on May 5, 2016
Latest reply on May 5, 2016 by harryh

Dear Sir/Madam,

With fully differential current feedback amplifiers like the ADA4927-1 are there any potential problems with adding an positive offset to the inverting input? The use case would be a unipolar input 0 to 1V on the non-inverting input and a 0.5V offset added to the inverting input. With a gain of 2 the full ADC range could be used (ADC with 2Vpp differential). If multiple FDAs are used in this configuration would it be better to use:

a) One LDO for all the FDAs offset

b) One LDO for each FDA offset

c) One LDO for all FDAs buffered using a unity gain buffer for each FDA?

If the unity gain buffer is the better solution would this device require any special attention ie. bandwidth

Thanks Grant