– 5-16 –
The U2011 features a speaker amplifier for playback synthesized tones though an internal amplifier before application to 8
Ω
speaker, and a stereo headset amplifier output. For desktop handsfree applications, the voiceband downlink signal from the
U2001 (E-Gold + V3). Series resistors/capacitors adapts the 8
Ω
speaker to output drive capability of the U2001, and protects
the speaker outputs of the U2001 against the large voltage swing of the U2011 output amplifier.
Z1, Z2 and Z3 tailor the frequency response and gain of the speaker amp.
The U2011 features two SW controllable outputs, intended for vibrator. If the synchronization features of the SMAF format
should be 100% utilized, these outputs should be used to drive the vibrator.
5.2.8. AUDIO
■
Receiver
Because U2001 runs off 2.7 V, a high impedance ceramic speaker will not satisfy user requirements for volume, therefore, a
lower impedance dynamic type is used.
GSM requires that the receive audio frequency response must fit within the mask shown below:
RSFR (dB)
4
2
0
-2
-4
-6
-8
-10
-12
-14
1,000
100
log Frequency (Hz)
Figure 5.11. GSM Receive Audio frequency response mask
Level
VG1RX
SM_SCAL_OUT
SM_SCAL_REC
Total Gain
1
0 dB
6 dB
–4.5 dB
1.5 dB
2
–6 dB
6 dB
–1.5 dB
–1.5 dB
3
–6dB
6dB
–4.5dB
–4.5dB
4
–12dB
6dB
–4.5dB
–10.5B
Summary of Contents for EB-X400
Page 86: ...12 1 12 LAYOUT DIAGRAMS 12 1 Main Board U2001 ...
Page 87: ...12 2 ...
Page 88: ...12 2 Upper Face PCB 12 3 Green Black Black White ...
Page 89: ...12 3 Hinge PCB 12 4 ...
Page 90: ...12 4 SIM PCB 12 5 ...