PCF50732H/F1 데이터 시트보기 (PDF) - Philips Electronics

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PCF50732H/F1

Baseband and audio interface for GSM

Philips Electronics 

Philips Semiconductors

Baseband and audio interface for GSM

Objective specification

PCF50732

20

handbook, full pagewidth

gain

(dB)

0

MBL025

−20

ZIF

−40

NZIF

−60

−80

−100

0

100

200

300

400

500

600

f (kHz)

3

Fig.3 Transfer functions for the baseband receive filter.

9.3 Baseband Serial Interface (BSI)

9.3.1 OVERVIEW

The digital part of the baseband consists of a receive

section and a transmit section. The receive section is a

FIR filter that reduces the 6.5 MHz (13 MHz for

NZIF mode) bitstream from the sigma-delta converters

into 2 × 12-bit values at 270.833 kHz (541.667 kHz for

NZIF mode).

The transmit section converts the 270.833 kHz data

stream from the DSP into a GMSK signal sampled at

4.333 MHz. The 10-bit I and Q signals are then fed into

two 10-bit DACs. The power ramping signal is also

generated by the transmit section with the 10-bit

AUXDAC3 block.

9.3.2 TRANSMIT PATH BLOCK DESCRIPTION

9.3.2.1 Transmit serial interface

The power-up of the BSI transmit path is controlled via the

TXON pin. When TXON is pulled HIGH, the transmit path

recovers from power-down. The MCLK/48 = 270.833 kHz

output signal BIOCLK is activated. When the BIEN0 period

has elapsed the output signal BIEN goes LOW and the bits

to be transmitted are clocked out of the DSP.

BIEN0 must be at least 10 quarterbits long to allow settling

of the analog filters. Bits are clocked out of the DSP by the

falling edge and clocked into the PCF50732 by the rising

edge of BIOCLK. After the BIEN1 period has elapsed,

BIEN is set HIGH again and transmission from the DSP

ends. Logic 1s are modulated whenever BIEN is HIGH

and the baseband transmit (BBTX) block is active. Values

for BIEN0 and BIEN1 can be set in the Burst control

register.

Figure 5 shows the timing for the BSI data transmission.

In power-down the de-asserted value of BIOCLK is high-Z

and BIEN is HIGH. Typical connection to the system DSP

is defined in Table 1.

Table 1 Connection of BSI transmit signals to

PCF5087X

PCF50732

PCF5087X

PIN

TXON

BDIO

BIEN

BIOCLK

I/O

PIN

I/O

I

RFSIG[y]

O

I/O

SIOXD

I/O

O

SOXEN_N

I

O

SIOXCLK

I

1999 May 03

11

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