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LEON-G100/G200 - System Integration Manual

GSM.G1-HW-09002-C Preliminary System description

Page 35 of 75

Mount a 33 nH series inductor (e.g. Murata LQP15M33NG02) on each microphone line, and a 27 pF

bypass capacitor (e.g. Murata GRM1555C1H270J) on all audio lines to minimize RF coupling and the

TDMA noise

Figure 21: Headset connector application circuit

1.9.1.5 Hands-free mode

Hands-free functionality is implemented using appropriate DSP algorithms for voice band handling (echo

cancellation and automatic gain control), managed via software. The viva voice operation provides the possibility

to realize a phone call with a loudspeaker and a microphone. The audio path used in hands-free mode:

Microphone is connected to the input pins MIC_BIAS1/MIC_GND1

High power loudspeaker is connected to the output pins SPK_P/SPK_N.

When hands-free mode is enabled, the audio output signal on HS_P is disabled.

The physical width of the high power audio outputs lines on the application board must be wide enough to

minimize series resistance.

Figure 22 shows an application circuit for hands-free mode. In this example the LEON-G100/G200 module is

connected to an 8 Ω speaker and a 2.2 kΩ electret microphone. Insert a 33 nH series inductor (e.g. Murata

LQP15M33NG02) on each microphone line and a 27 pF bypass capacitor (e.g. Murata GRM1555C1H270J) on all

audio lines to minimize RF coupling and the TDMA noise.

LEON-G100/G200

HS_P

MIC_GND2

MIC_BIAS2

HS_DET

LEON-G100/G200

HS_P

MIC_GND2

MIC_BIAS2

HS_DET

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MaxTech NXP-16 Dokumentacja Strona 35