Hi everyone,
I'm trying to build an ADC driver for over 100 Mhz sampling rate. In my application I need to sample from DC to 60 Mhz. For that purpose I choose ads4541 as adc and ths4541 as FDA. I built a butterworth low pass filter in front of the FDA(cutt off frequency is nearly 60 mhz) and match the filter input and output impedances to 50 ohms. I also did the input impedance matching for the FDA to 50 ohm. But the think is when I simulate those two with the TINA-TI software results came I little weird to me. from dc up to 1k hz gain of the complete circuit is around -6 dB. Can that FDA behaves as simulation shows or is it a simulation mistake. When I checked the datasheet of FDA.TI only shows the response of the amplifier from the 1Mhz range. does that mean this FDA is useless in the DC to 1 Khz range. Results are as follows:
here is the circuit
