One of my customers is using ADL5375-15 Quadrature Modulator for his prototype board.
High-Speed DAC generates analog I/Q signal and is fed to ADL5375-15 through reconstruction filter designed by him.
Attached file “SSB-compression” shows sideband suppression performance taken by him.
Frequency condition is f0=3GHz, I/Q input freq=27MHz, LO=3GHz.
Thank you for your help.
Sideband suppression performance is a parameter of gain and phase imbalance between I and Q that are related to EVM performance in system level. By optimizing amplitude(gain) and phase more, then we can get better number on sideband suppression. However, around -50dB sideband suppression would be reasonable for that BB range and it would be enough for EVM at communication application. Please refer to below link.
For flatness over +/-24MHz signal band, there would be three factor mainly. Roll-off(sinx/x) from DAC, Baseband flatness of ADL5375-15, RF Flatness over 48MHz at 3GHz on ADL5375-15. It would be around -0.53dB from DAC roll-off at 24MHz. Approximately around 0.1dB at 24MHz from Baseband of ADL5375-15(Refer to Fig 64 in datasheet). Not much from RF Flatness (Refer to Figure 28 for RF flatness). So 3dB at +/-24MHz is big. It might be good to check DAC output and then move to Modulator to narrow down the issue.
Thank you for your detailed explanation.
I will talk to my customer based on your advice.