ADL5511 Response to a Multi-Carrier Signal

Document created by enash Employee on Jul 21, 2014
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Question: The datasheet shows the part working with a single 20MHz LTE carrier but can our part also function for 2 or even 3 carriers?  Has anyone at ADI tested this?

Answer: We have not tested the envelope response with multiple carriers. But we have measured the envelope bandwidth to be 130 MHz. We did this by sweeping the modulating frequency of an AM carrier at a fixed carrier frequency; we kept increasing the modulating frequency until the peak-to-peak of the output sine wave (i.e. the demodulated AM) was down by 3 dB.

The ability of the ADL5511 to follow the envelope of a multi-carrier signal will be limited by the net bandwidth of the carriers. If it's two adjacent 20 MHz LTE carriers, it will work fine because the net bandwidth of 40 MHz is significantly ess than 130 MHz. If it's two carriers that are non-adjacent and separated by more than around 60 MHz (see Figure 39 in the datasheet which shows the response starting to fall at around 60 MHz), then the tracking is not going to be as good because the net bandwidth is equal to Fmax-Fmin. .