LTC5577 Performance with 40-80MHz IF

The LTC5577 IF gain seems to have a lot of ripple, looking at the datasheet figure 11.

What is the expected ripple and gain when using a 40-80MHz IF (with, say RF: 1500-4500MHz)?

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    •  Analog Employees 
    on Jul 8, 2019 9:57 PM over 1 year ago

    The ripple is not bad at all. What is your requirement?

    Looking at datasheet plot G03, I would say Gc slopes down from 0.7dB at 1500MHz to 0dB at 4300MHz. That is only 0.7dB tilt across almost 3GHz. The periodic ripple is likely due to measurement system. Even that is only about +/-0.2dB.

    Figure 11 is a sweep across IF frequencies. The transformer loss is included in the plot. The ripple from 40MHz to 80MHz looks to be +/-0.2dB.

  • Thanks - I was just surprised at the rapid ripple in Gc for the 50Ohm curve at 10-110MHz IF, compared to the smoothness at 110-1010MHz. However, as I need somthing that goes down to about 100MHz RF in (change of architecture), I will look into a few other mixers....

  • +1
    •  Analog Employees 
    on Aug 1, 2019 10:01 PM over 1 year ago in reply to Laudio

    The data used to generate the plots was measured on evaluation boards which includes all parasitics and losses. The IC's actual gain flatness across 10-110MHz is flatter than the apparent 0.5dB ripple.

    I see that you started another discussion on wideband input mixers LTC5510 and ADL5801. I explained some of their differences in that thread.

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