How to interface two wire & three wire SPI device?
The "SPI" in your microcontroller stands for "Serial Perpheral Interface", which is an industry standard I/O port originally defined by Motorola. But the "SPI" in the Analog Devices' AD converter stands for "Serial Port Interface", which is not the same as the SPI in your microcontroller. It's Analog's own definition for a digital interface.

Analog has written an application notes on how to communicate with this port. It can be found here:

AN-877 Interfacing to High Speed ADCs via SPI:
http://www.analog.com/static/imported-files/application_notes/56755538964965031881813AN_877.pdf

You might be able to use your microcontroller's SPI port for this, at least partly - the Atmel protocol seems at least somewhat compatible with Serial Peripheral Interface. You could connect your microcontrollers MISO port to the Atmel's SDIO port and then bit-bang the instruction header from your microcontroller to the ADC and then use the hardware SPI to read the data. Or you perhaps could connect both MOSI and MISO together in your MCU and use the pin's direction and mode bits (input-or-output, gpio-or-peripheral) to essentially disable the MOSI pin when you're reading data and MISO pin when you're writing data.