DAC Output Discrepency between Channels

[linuswck]

Description

DAC Output 0 and DAC Output 1 should have the same output voltage range but it is not. I suspect there is something wrong with the DAC AFE Stage.

The prototype board we received has the ADA4930-2YCPZ used as a differential to single end converter but the differential to single end operation is not specified in the OpAmp datasheet.

Point of Measurement

Measurements are taken with Fluke 87V at the AD9117-2 output resistors and DAC SMA Output Port.

Measurement Result

	AD9117-2 Output	DAC SMA Output	Unsigned Data
Channel 0	-427.8mV	-157mV	0x0000
Channel 1	-426.1mV	-163mV	0x0000
Channel 0	429.2mV	258mV	0x3FFF
Channel 1	424.3mV	323mV	0x3FFF

Note1: AD9117-2 DAC is set to receive unsigned data before the measurements are taken.
Note2: This behavior also exists on another unmodified, freshly opened fast servo board.

Edited: Add Note2.

[gkasprow]

Every opamp is specified for diff to SE conversion.