Panasonic KX-TCD775RUS Service Manual ▷ View online
7.3. RF Module
BLOCK DIAGRAM RF MODULE
Loop
filter
CHP
VCO
x2
PD
:R
:N/A
32/33
PLL &
control logic
S&H
Demodulator
Printed
balun
Printed
balun
Printed
PMB6819
Power amp.
DRON
RXON
RX Part
TX Part
voltage
regulator
voltage
regulator
VCC1
VCC
VCC2
Low IF
band pass
filter
VCC
VCC1
TXDA
SYRI
SYDA
SYCL
SYCL
RXDSG
RXDA
RSSI
SYEN
3.3V
PMB6610
DECT transceiver
PAON
PAON
Diversity
Switching
ANT1
ANT2
ANT2
RF1
RF2
Fig. 22
7.3.1. RF Module (See BLOCK DIAGRAM Fig.22)
The RF Module consists of two main components: the PMB6610 transceiver and the PMB6819 power amp.
In the transceiver the 10.368MHz clock signal SYCL is multiplied to around 1.9GHz using PLL (Phase Locked Loop) control.
The TXDA signal is used to control the modulation of this frequency to 1.87GHz to 1.93GHz.
Received signals are demodulated, filtered and sent to the BBIC via the RXDA line.
The RSSI (Radio Signal Strength Indicator) signal enables the implementation of diversity switching whereby two antennae can
be mounted in different orientations and their signals compared. The one with better reception can be selected by the BBIC
using the ANT1 and ANT2 lines.
In the transceiver the 10.368MHz clock signal SYCL is multiplied to around 1.9GHz using PLL (Phase Locked Loop) control.
The TXDA signal is used to control the modulation of this frequency to 1.87GHz to 1.93GHz.
Received signals are demodulated, filtered and sent to the BBIC via the RXDA line.
The RSSI (Radio Signal Strength Indicator) signal enables the implementation of diversity switching whereby two antennae can
be mounted in different orientations and their signals compared. The one with better reception can be selected by the BBIC
using the ANT1 and ANT2 lines.
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KX-TCD775RUS
BLOCK DIAGRAM
8 CIRCUIT OPERATION (HANDSET)
CPU
IC1
A/D
D/A
Analog
Front
End
Speech Encoding
Speech Decoding
Burst Encoding
Burst Decoding
DSP
ADPCM
Codec
Filter
BMC
RF
Interface
Interface
SPEAKER
MIC
EEPROM
IC2
SDA
SCL
64
65
5
6
SYRI
RSSI
SYEN
RXDA
TXDA
14
10
46
21
11
RF
Section
Section
ANT
BATTERY
TERMINAL
J1
J2
CHARGE
CIRCUIT
CHARGE
CHARGE DETECT
SWITCHED
SUPPLY
CHARGE
CONTACTS
CONTACTS
J3
J4
2.4V
Reg.
3.6V
VDDBAT
SENSE
SWITCH
SWITCH
31
29
XTAL
10.368
MHz
KEYPAD
COLUMNS
ROWS
LCD
7 Seg
Display
7 Seg
Display
ON SWITCH
36
25
24
34
26
24
KX-TCD775RUS BLOCK DIAGRAM (HANDSET)
J7
67
63
63
50
86
DL1/INH/RS
CS/CE
DISCLK
DISDATA
Flash
PROM
IC3
PROM
IC3
30
85
ADDRESS
DATA
A0..
A17
A17
D0..
D7
D7
69
SP_AMP
J6
Headset
EARPIECE
AMPLIFIER
39
43
40
RX-AF
47
TX-AF
KEYPAD LED'S
78
79
RED BACKLIT
GREEN BACKLIT
Fig. 23
22
KX-TCD775RUS
8.1. The Base Band Section
8.1.1. Introduction
The base-band section consists of a base-band integrated circuit (BBIC), a Flash PROM, an EEPROM, Serial Port, Audio paths
both TX and RX, Speakerphone, Microphone, Earpiece, an LCD Display, and power supply/battery management circuits.
both TX and RX, Speakerphone, Microphone, Earpiece, an LCD Display, and power supply/battery management circuits.
8.1.2. The Base - Band Integrated Circuit (BBIC)
IC1 is a Universal Mobile Controllder (UMC) designed to handle all the audio, signal and data processing needed in a DECT
handset. It contains a "burst mode controller" which takes care of DECT specific physical layer and radio section control. It also
contains an ADPCM codec filter used for speech encoding and decoding in the DSP section, a general purpose microcontroller,
various other ADC´s, DAC´s, timers and power control circuitry.
The BBIC interfaces to its external PROM (IC3) via a data/address/control bus. It connects to the EEPROM (IC2) via a serial
interface (SDA and SDC). This serial interface is also used during manufacture and service to connect to an external computer.
handset. It contains a "burst mode controller" which takes care of DECT specific physical layer and radio section control. It also
contains an ADPCM codec filter used for speech encoding and decoding in the DSP section, a general purpose microcontroller,
various other ADC´s, DAC´s, timers and power control circuitry.
The BBIC interfaces to its external PROM (IC3) via a data/address/control bus. It connects to the EEPROM (IC2) via a serial
interface (SDA and SDC). This serial interface is also used during manufacture and service to connect to an external computer.
8.1.3. FLASH ROM (See Fig. 24)
The 4Mbit Flash PROM IC3 contains the operational firmware for the BBICs general purpose microproccessor. It is interfaced
to the BBIC using address lines A0 to A7, data lines D0 to D7, and control lines CE (Chip Enable), WR (Write Enable and OE
(Output Enable).
to the BBIC using address lines A0 to A7, data lines D0 to D7, and control lines CE (Chip Enable), WR (Write Enable and OE
(Output Enable).
8.1.4. EEPROM (See Fig. 24)
The electrically erasable PROM IC2 is used to store all the temporary operating parameters for the handset (see EEPROM
LAYOUT). It used a two-line serial data interface with the BBIC, with bi-directional data on IC2 pin5 (TP52), and a 45 kHz clock
on pin6 (TP53).
LAYOUT). It used a two-line serial data interface with the BBIC, with bi-directional data on IC2 pin5 (TP52), and a 45 kHz clock
on pin6 (TP53).
8.1.5. Factory Serial Port (See Fig. 24)
In order to communicate with the handset during manufacture and servicing (using a PC) a serial data link has been provided.
Serial data input/output is provided through the I2DAT input (pin 64). The data is clocked through using the I2CLK pin (65). Test
probe pads SDA and SDC are provided for external connections with I2DAT and I2CLK respectively.
To invoke the flash PROM download mode the DL1 and DL2 test pads need to be pulled low and high respectively.
A Ground reference solder pad is also provided.
Serial data input/output is provided through the I2DAT input (pin 64). The data is clocked through using the I2CLK pin (65). Test
probe pads SDA and SDC are provided for external connections with I2DAT and I2CLK respectively.
To invoke the flash PROM download mode the DL1 and DL2 test pads need to be pulled low and high respectively.
A Ground reference solder pad is also provided.
23
KX-TCD775RUS
Fig. 24
8.1.6. Audio Path - TX Audio (See Fig. 25)
The audio signal from the microphone (TP37) enters the BBIC at pin 43. RF decoupling and signal conditioning are provided
by C17, C21, R21, R8, C15 and C14.
In the BBIC the signal passes through the analogue section where it is amplified and converted to a digital audio stream signal.
The burst mode controller processes this stream performing encryption and scrambling, adding the various other fields to
produce the GAP standard DECT frame, assigning to a time slot and channel etc. to emerge on pin 14 as TXDA.
by C17, C21, R21, R8, C15 and C14.
In the BBIC the signal passes through the analogue section where it is amplified and converted to a digital audio stream signal.
The burst mode controller processes this stream performing encryption and scrambling, adding the various other fields to
produce the GAP standard DECT frame, assigning to a time slot and channel etc. to emerge on pin 14 as TXDA.
8.1.7. Audio Path - RX Audio (See Fig. 25)
Audio from the receiver RXDA enters the BBIC on pin 10 as GAP standard DECT frames. It passes through the decoding
section burst mode controller where it separates out the frame information and performs de-encryption and de-scrambling as
required. It then goes to the DSP where it is turned back into analogue audio. This is amplified by the analogue front end and
emerges at pin 39 and 40. The earpiece is driven directly from the BBIC output ports.
section burst mode controller where it separates out the frame information and performs de-encryption and de-scrambling as
required. It then goes to the DSP where it is turned back into analogue audio. This is amplified by the analogue front end and
emerges at pin 39 and 40. The earpiece is driven directly from the BBIC output ports.
24
KX-TCD775RUS
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