TCM4400EPET datasheet(45/64 Pages) TI

45 / 64 page

TCM4400E

GSM/DCS BASEBAND AND VOICE A/D

AND D/A RF INTERFACE CIRCUIT

SLWS082A – JULY 1999 – REVISED MARCH 2000

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

PRINCIPLES OF OPERATION

Read operation from the downlink baseband codec is done using the TX part of the DSP/MCU serial interface

in the following 16-bit word format given in Table 5.

Table 5. 16-Bit Word Format

DATA

ADDRESS

During reception of a burst, transfer of RF data from the downlink baseband codec is done using the transmit

part of the DSP serial interface in the following 16-bit word format: As the I and Q samples are coded with 16-bit

words, the data rate is 270833

× 16 × 2 which equals 8.66 Mbps. I & Q samples are differentiated by setting the

LSB to zero for I samples and to one for Q samples. Since the digital clock MCLK is 13 MHz, transfer is done

at 13 Mbps in burst mode. During burst reception the DSP serial interface is idled about 33% of the time.

Table 6. Format of 16-Bit Word Transfer

DATA

I/Q

D15

D14

D13

D12

D11

D10

DSP/MCU serial interface registers

The following internal register buffers are accessed using the DSP/MCU serial interface during manual

operation of the TCM4400E.

baseband uplink ramp delay register

Each bit position of the baseband uplink ramp-delay register is given in Table 7.

Table 7. Uplink Ramp-Delay Register

BULRUDEL: BASEBAND UPLINK RAMP DELAY REG.

ADDRESS: 1

R/W

RESERVD

IBUFPTR

DELD3

DELD2

DELD1

DELD0

DELU3

DELU2

DELU1

DELU0

1 / 0

R = 0

R/W

<––– ACCESS TYPE

<–––VALUE AT RESET

DELU0 to DELU3

: Value of the delay of ramp-up start versus the rising edge of BENA

DELD0 to DELD3

: Value of the delay of ramp-down start versus the falling edge of BENA

IBUFPTR

: Writing a 1 in this bit initializes the pointer of the burst buffer to the base address.

(This is not a toggle bit and has to be set back to 0 to allow writing into the burst

buffer).

RESERVD

: Reserved bits for testing purposes

R/W

: A 1 indicates a read operation; a 0 indicates a write operation.

TCM4400EPET Datasheet(PDF) 45 Page - Texas Instruments

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