I want to connect AD9783 and LTC5588-1.

Hi Hitara-San

you can use a standard approach to connecting the AD9783 DAC to the LTC5588. 

1. Set the full-scale current of the DAC to 20 mA.
2. Connect four 50 ohm resistors from the four DAC outputs (IOUT1P, IOUT1N, IOUT2P, IOUT2N) to ground. This will result in each output having a peak to peak swing of 1Vpp and a common mode level of 0.5V.
3. This gives each DAC and effective differential output resistance of 100 ohms.
4. At the IQ Modulator baseband inputs, connect a 100 ohm resistor between BBPI and BBMI. Connect another 100 ohm resistor between BBPQ and BBMQ. This will set the input impedance of the Baseband inputs to approximately 100 ohms (it will be a little bit less because the input resistance looking into the baseband inputs is 3K; so you could make the external 100 ohms resistors slightly bigger to get a net input resistance of exactly 100 ohms).
5. Design a 100 ohm  anti-aliasing filter between the DAC and IQ Modulator.

6. Note that each DAC output now sees a  50 ohm resistor to groud along with the 100 ohm resistor across the IQ mod inputs. This will reduce the DAC output voltage swing but will not affect the common mode voltage of 0.5V.

    

7. I'm attaching some application notes that talk about this topic.

    

    

Best Regards

Eamon Nash

AN-1413 (Rev. B)

I/Q Modulator ADL5375 and AD9779A Interface-EEWORLD