Appendix A
64
Analog Outputs
The DT9822 function module provides two analog output channels
with a resolution of 16 bits.
The design of the DT9822 ensures that the analog outputs do not
break into a high frequency oscillation with high capacitance loads
that may be experienced with long cables. Typically, the analog
outputs drive 1,000 pF without degradation and bandwidth-limit
with higher capacitive loads.
The grounds of most boards are optimized for analog inputs at the
expense of some logic or high-frequency noise on the analog outputs.
This is because the analog and digital grounds of the board are
connected at the ADC’s input.
The analog outputs are brought out as a high and a low signal, but
the low side is the analog ground at the DAC’s output buffer. To
remove the high-frequency noise and smooth the glitch energy on the
analog outputs, you can install a 15 kHz RC filter on the output, a
100
Ω
resistor in series with the output, and a 0.1
µ
F capacitor
between the output side of the 100
Ω
resistor and output low.
