WM7121PE

8

Rev 4.1

CONNECTION TO A CIRRUS LOGIC CODEC

Cirrus Logic provides a range of audio CODECs incorporating an analog microphone input interface;

these support connection to silicon microphones such as the WM7121P.

The recommended connection of a WM7121P silicon microphone is illustrated in Figure 2 (for single-

ended mode) and Figure 3 (for pseudo-differential mode).

A DC blocking capacitor is required, as described in the previous section. A 2.2µF decoupling

capacitor is also recommended; this should be positioned close to the VDD pin of the WM7121P.

Further information on Cirrus Logic audio CODECs is provided in the respective product datasheet,

which is available from the Cirrus Logic website.

Audio CODEC

OUTPUT

MICBIAS

Analogue Input pin

(eg. IN1xP)

VDD

GND

1

F

WM7121P

2.2

F

Figure 2 WM7121P Silicon Microphone Single-ended Connection

1

F

Audio CODEC

OUTPUT

MICBIAS

Non-Inverting Input pin

(eg. IN1xP)

VDD

GND

1

F

Inverting Input pin

(eg. IN1xN)

WM7121P

2.2

F

Figure 3 WM7121P Silicon Microphone Pseudo-differential Connection

MATCHED MICROPHONE PAIRS

The WM7121P Top Port microphone offers matched performance to the WM7132P Bottom Port

microphone.

Matched microphone pairs are ideal for accurate sound pick-up from opposite directions in slim, low-

profile applications. For best acoustic matching, the Top Port and Bottom Port microphones should be

positioned close together, on the same side of the PCB.

The WM7121P and WM7132P microphones offer matched sensitivity, low-frequency roll-off, and

phase response characteristics, enabling simplified system design when using these complementary

devices.