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When input 192MHz bandwidth QAM256 signal, there is some spur frmo 40MHz to 120MHz. The input signal frequency is 189~381MHz,32channel, power level is -39dBm per channel. The amplifier is ACA2407. Why?
Re: spur!!!amplifier when input 192MHz bandwidth QAM256 sign
Since spur 2 is 2/3 the frequency of spur 3, that would suggest where they are coming from. What do you have in the system that is running at ~256 MHz?
Also, why is there a huge spectral drop-out around 280 MHz? Is that your LO frequency? Why is there a drop-out at 280 but not 256?
As far as the other spurs (lower frequency), well you have all sorts of intermod products. They can easily generate the spurs seen. What happens the the low frequency spectrum( in dBc) if you put a 10 dB pad before the amplifier?