WM3100
Preliminary Technical Data
Figure 3 Differential Line Input
OUTPUT SIGNAL PATH
The WM3100 provides two line output channels, which each support a peak output voltage of ±2.97V
(6.4dBV or 2.1VRMS sine wave) when operating with a 3.3V supply.
The line outputs are ground-referenced, removing the requirement for DC-blocking capacitors.
The WM3100 provides an internal low-pass filter (LPF) on the output paths. It is also recommended
to connect an external analogue low pass filter to the output pins. This ensures that all out-of-band
noise is filtered, and improves the maximum load capacitance rating, as noted in the “Electrical
Characteristics”.
There are many suitable LPF architectures, but a simple RC filter is recommended, as illustrated in
Figure 4. The filter shown here has a -3dB cut-off frequency of approximately 105kHz, and a droop of
-0.15dB at 20kHz.
Figure 4 Line Output Low Pass Filter
PTD, October 2010, Rev 2.0
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
