Sundance SMT350 - Manual (Page 13)

Version 1.9 Page 13 of 45 SMT350 User Manual
Dual-Channel DAC.
DAC Main characteristics.
The main characteristics of the SMT350 DAC are gathered into the following table.
Analogue Outputs
Input voltage range 1 Vp-p – Full scale - AC coupled
Impedance
DAC single-ended outputs are to be
connected to a 50
Ω load, which impedance
matching implemented between DAC and
RF transformers.
Bandwidth TBD
DAC Input
Output Data Width per channel 16-Bits
Data Format
2’s Compliment or offset binary
(Changeable via control register)
SFDR 89dBs maximum (manufacturer)
SNR 80dBs maximum (manufacturer)
Maximum input data rate 160 MSPS (Clk1 – DAC5686)
Maximum Sampling rate 500 MSPS (Clk2 – DAC5686)
Jumper J1 disables (position 1-2; also called External Clock Mode) or enables
(position2-3; also called Internal Clock Mode) the DAC internal PLL.
DAC output stage.
The following piece of schematics shows how the DAC outputs are coupled. The
DAC5686 generates differential output signals that are fed into an RF transformer
(Ohm ratio 4), that makes both DAC channels AC coupled. 100-Ohm resistors to Vcc
on the primary stage of the transformer allow balancing the secondary stage to 50
Ohm single-ended. (Note that R153 is not mounted).