Other Parts Discussed in Thread: ADS4249
Hello,
In my application I sample 2 analog signals at 250 MHz. using ADS4249, transmit it and reconstruct it using DAC3482.
I noticed that DAC3482 has internal interpolation filters. Because of my sampling rate, I can use maximum X4 filter (DAC works up to 1.25 GHz) . I understand that those filters are for easy smoothing of the output Analog signal.
The question is whether those filters would remove any frequency higher than 125 MHz. which is sampled at the ADC stage?
What would happen if there is a 200 MHz. component in the Analog signal input? (i.e. ADC input). Would the interpolation filter remove this frequency? (because 200 MHz. is higher than 250 MHz. X 0.6 = 150 MHz.) or there would be folding (aliasing) and I will see a peak at 50 MHz. at the Analog output?
If I would see this peak, what is the way to filter it without losing my bandwidth? I need a bandwidth of DC-100 MHz.
Traditional anti aliasing filters (with linear phase) are -20, -40 or -60 dB's per decade so if I will make a 6'th order filter with -60 dB's per decade and a 100 MHz. Bandwidth (i.e. -3dB's at 100 MHz. = about -10 dB's at 200 MHz.) then I would still get aliasing. Higher order filters do not work at those frequencies because they accumulate DC offset error (and higher delays).
Is there any better way to do it without losing my DC-100 MHz. bandwidth and without the need to buy a much faster ADC and do digital filtering in the FPGA which samples (because it is expensive... Faster ADC and faster FPGA = more $$$).
I would appreciate your fast and detailed response.
