LMH6554: Regarding the review of ADC & DAC (DAC5652A) design

Hi Mastik, 

Please allow a slight delay in response, it is a holiday in the US today, we will get back to you as soon as possible. 

Best, 

Jacob 

Hello Mastik,

  We have reviewed the amplifiers in the schematic:

1. THS4021
   1. This is a decompensated amplifier with a gain requirement of 10V/V. The note says Gain of 12, but the configuration shows around 7V/V. 
   2. The DAC is current source output with 300kOhm output resistance, it is recommended to match the impedances at each output. An example is shown in Figure 4 of DAC2902 datasheet Figure 4. Also app notes covering interfacing with current source DACs: Part 2 and Part 3 Simplified.
      
      
2. LMH6321
   1. Would recommend adding a series resistor prior to the input of the amplifier depending on amplifier placement compared to the pre amplifier stage. This can be 0 to 5 ohm resistor. 
      
      
3. OPA695
   1. Which filters will be configured here? It looks like LPF and BPF. Active filtering using current feedback amplifiers can be a bit difficult. It is possible, but does require tuning and initial simulation testing. This is because it is not recommended using capacitors in the feedback of a current-feedback amplifier due to stability concerns.
      
      
4. LMH6554
   1. Fully differential amplifiers require both paths to be symmetrical. IN+ and IN- to the device have different impedances

Thank you for your patience,

Sima