Cirrus Logic CDB4244 - Manual (Page 17)

DS900DB2 17
CDB4244
5 ANALOG OUTPUT FILTERS
The CDB4244 allows the user to evaluate the CS4244 using five different output filter configurations: passive single
ended, passive differential, active single ended, active differential, and active differential to single ended.
Figure 8
demonstrates the available options on the board.
Figure 8. Analog Output Filter Block Diagram
Each output filter option is realized by populating certain components and removing others. Section 5.2 on page 19
contains a comprehensive list of components, and Figure 18 on page 31 contains a silk-screen diagram to aid in
locating each component. By default, the CDB4244 is configured to use a passive differential filter on each output
channel.
5.1 Analog Output Filter Considerations
If any of the three active output filter configurations are used, a dual-rail ±12-V supply must be connected
to the CDB4244 to power the operational amplifiers used in these filter designs. The dual-rail supply is not
required for the passive single-ended or differential output filter options, but is still required when using the
default active single-ended-to-differential filter network on the input channels of the CDB4244. As men-
tioned in
Section 4.2 on page 15 , if every input and output channel is configured to use a passive filter net-
work, the ±12-V supply may be removed.
The negative supply rail of the active output filter network can be tied to -12 V or ground to provide the option
of a dual-rail or single-rail supply, respectively. The dual-rail supply is achieved by populating R141 with a
0-
Ω 0603 SMT resistor and omitting R142. Omitting R141 and populating R142 allows for a single-rail sup-
ply. This is shown in Figure 17 on page 30 . The CDB4244 is configured to use a dual-rail supply by default.
Note, however, that exercising the single-rail supply option limits the voltage swing of the output signal. Driv-
ing a full-scale output signal with a single-rail supply severely clips the analog output signal.
Passive Filter Network
Active Filter Network
Output +
Output -
Active Filter Network
(Differential to S/E)
Passive Filter Network
Active Filter Network
AOUT+
AOUT-
CS4244