In page 28 of datasheet, in the 'Maximum input power (PIN_0dBFS and IDAC1FS) ' section, it shows that a differential voltage swing of ±240mV peak is obtained for IDAC1FS equals 4mA. This where I feel puzzled. The reason is as following:
thus, we analysis the input stage of AD6676 in the single ended, the single ended input resistance is RIn_single=30Ω,
since IDAC1FS=4mA, current swing provided by IDAC1 is ±2mA peak .
so, single-ended voltage swing of ±2mA × 30Ω=±60mV peak is obtained for IDAC1FS equals 4mA.
i.e. a differential voltage swing of ±120mV peak is obtained for IDAC1FS equals 4mA.
Why my result is different from the datasheet? Where is wrong?