Hi,
My customer is using ADC08B3000.
He wants to input Vin+/- single-end input signal.
The method of inputting single-end signal is showed Figure 46 in datasheet.
But customer condition is that input signal(single-end) range is 0V~4V.
I think that LMH6555 can not receive the input range and AD Converter can not receive the input range.
Could you let me recommend fully differential amp and circuit at this situation, please?
Best regards,
Shimizu
Hi Shimizu
The LMH6555 has a fixed gain of 13.7dB. For that reason it is not an appropriate amplifier to use when converting a large amplitude single ended signal to drive the differential ADC inputs.
Something like the LMH6554 would be more appropriate. I created a basic starting point circuit in TI-TINA to demonstrate what is needed to achieve the needed gain and voltage offset to drive an input like that of the ADC08B3000. (Vcm = 1.26V, Vfsr=0.8Vpp diff).
Here is the basic schematic and results. Please note that the necessary decoupling capacitors, etc. must all be added to create a properly optimized circuit. I would recommend adding a differential lowpass filter at the amplifier output to roll off harmonics that are outside the desired frequency range.
Best regards,
Jim B
