– 5-11 –
Figure 5.10. AD65
37
Functional Block Diagram
The microphone is a noise canceling type to provide improved speech pick-up, noise immunity and reduced echo.
The GSM standard requires that when in handheld mode, the transmitter audio frequency response must fit within
the mask shown below:
Figure 5.11. Handheld GSM Transmit Audio Frequency Response Mask
5.3.2. Microphone
5
0
-5
-10
-15
1,000
10,000
100
Frequency (Hz)
(dB)
In base-band power management, ADI AD6537 is designed for all base-band main power supply.
It provides seven regulator outputs for VCORE (1.8V), VMEM (2.93V), VEXT(2.93V), VRTC (1.8V), VCTCXO (2.75V), VSIM (2.85V),VMIC(2.75V).
VCORE and VMEM provide all digital power and VMEM provides all analog power. VRTC is used to charge Li-Mn coin cell for real time clock, and
VCTCXO is the power source of 13MHz clock buffer. Besides, AD6537 is also combined charge pump and hardware reset.
The following is the detailed description:
Mic
Filter
Filter
Filter
Filter
Tone
Battery
Charger
Light
Controllers
8 Voltage Regulators
Crystal &
Varactor
LEDs
Headphones or Headset
VCORE: 1.8 V, 80 mA
VRTC: 1.8 V, 200
µ
A
VMEM: 2.93 V, 150 mA
VSIM: 2.85 V, 20 mA
VEXT: 2.93 V, 170 mA
VABB
VMIC: 2.75 V, 1 mA
VVCXO: 2.75 V, 10 mA
CSPORT
BSPORT
ASPORT
Switch
GMSK
Ram
AD6625
or
AD6626
AD6337B
DAC
DAC
DAC
DAC
DAC
ADC
ADC
ADC
ADC