WM8714

Production Data

w

PD Rev 4.0 November 2004

15

RECOMMENDED ANALOGUE LOW PASS FILTER (OPTIONAL)

+

_

+

+VS

-VS

10uF

51

Ω

7.5K

Ω

680pF

1.8k

Ω

47k

Ω

4.7k

Ω

4.7k

Ω

1.0nF

Figure 7 Recommended 2

An external low pass filter is recommended (see Figure 7) if the device is driving a wideband

amplifier. In some applications, a passive RC filter may be adequate.

PCB LAYOUT

1.

Place all supply decoupling capacitors as close as possible to their respective supply pins

and provide a low impedance path from the capacitors to the appropriate ground.

2.

Separate analogue and digital ground planes should be situated under respective analogue

and digital device pins.

3.

Digital input signals should be screened from each other and from other sources of noise to

avoid cross-talk and interference. They should also run over the digital ground plane to avoid

introducing unwanted noise into the analogue ground plane.

4.

Analogue output signal tracks should be kept as short as possible and over the analogue

ground plane reducing the possibility of losing signal quality.