AD9901: O/P configuration

Question Is it required that the inververted output of the AD9901 is connected to the non inverted output by a resistor as pictured in Figure 12 of the data sheet and one of them put to ground , or is it possible just to use one of the outputs, biased as in Figure 1? Answer The AD9901 o/p’s are open collector o/p’s whose o/p compliance range changes, depending on whether you use the device in ECL mode or TTL mode..if you use the device in ECL mode, then the o/p compliance range includes gnd, and in this mode you can tie one of the o/p’s to gnd, and just use a single o/p as shown in fig12, or alternatively you can use both o/p’s as shown in fig1. When using the device in TTL mode, the o/p compliance range dies not include zero. So in this case you cannot tie one of the o/p’s to gnd.