I haven't found any information to connect ADRF6806 to the ADCs, is it necessary a driver? Have I to insert a LPF? What you suggest about ADC?
Can you give more information about your application? This will help us narrow down which driver and ADC would be best.
The ADRF6806 should drive an ADC directly. it is characterized to drive high impedance like 400ohms and the common mode range is 1.55-1.75V which is high for most modern ADCs. What would be best is to follow the demod with a low pass filter, then a stage of amplification, then a filter that will attenuate the wide band noise of the amplifier, then into the ADC. Depending on your frequency content and signal bandwidth we can make better recommendations for each of these stages.
Some questions: What is your signal bandwidth and frequency content, what does the signal look like? How much resolution do you need from the ADC? Is power a concern? What FPGA are you going into? What output signal do you want from the ADC? Is cost a factor?
Let us know and we can guide you in the right direction.
Here is the products suggestions from the website:
ADRF6806 Datasheet and Product Info | Analog Devices
The bandwidth is 56 MHz, resolution 14 bit, power isn't so important, FPGA is Kintex, cost is to be considered
I assume you mean you need DC-56MHz. If this is the case you will need an ADC that samples at least twice 56MHz, or more than 112Msps. Depending on how much filtering you need you will want to sample faster than that. I would recommend the AD9258, a 14 bit 125Msps part, the LTC2208-14 a 14 bit 130Msps, there is also a 160Msps version the LTC2209 if you want more guard band. If you have multiple channels, let me know and I'll recommend other parts.
For the amplifier to drive these, the LTC6409 is good and runs off of a single supply, the ADA4930 is also a good choice. If you need lower power but less performance the ADA4927-1 is also a good choice.
Look through those ADCs and amps and we can start helping with the signal chain.
Here is an article I wrote on the ADA4927 driving the LTC2185 (a 16 bit part). This might help you with your design.
Uncompromising Linearity from the LTC2185 and ADA4927-1
The baseband outputs want to see a 450 Ohm differential impedance. Impedances lower than this will limit its signal capacitor (current limited).
You'll need the LPF between the ADC and whatever is driving the ADC to avoid aliasing.
What is your application? Do you need any variable gain or programmable filtering?
The ADC will depend on your signal bandwidth (which will determine the sample rate). From there you can select an ADC with compatible common-mode voltage to the ADRF6806. You will need to determine was ADC resolution you need.
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