PCF50732H/F1 Ver la hoja de datos (PDF) - Philips Electronics

Número de pieza

componentes Descripción

Lista de partido

PCF50732H/F1

Baseband and audio interface for GSM

Philips Electronics 

Philips Semiconductors

Baseband and audio interface for GSM

Objective specification

PCF50732

10.1.5 EARAMP

EARAMP is an amplifier, capable of driving a standard

earpiece with a minimum impedance of 8 Ω in

single-ended mode or 16 Ω in differential mode.

10.1.6 AUXAMP

AUXAMP is an amplifier for connection to an external

loudspeaker amplifier of minimum 8 Ω (hands-free car kit).

An ‘auxiliary speaker external amplifier control’ output

pin (AMPCTRL) can be used to switch on/off an external

amplifier (hands-free car kit). The status of AMPCTRL is

programmable via the Control Serial Interface; its default

value is on.

10.1.7 BUZAMP

BUZAMP is an amplifier for connection to an external

buzzer of minimum 8 Ω. It has the same output

characteristics as the AUXAMP and can hence be used as

a second auxiliary output amplifier. It is switched on/off by

a dedicated control bit in the Control register block.

10.2 Voice band transmit path

The voice band transmit path consists of the following

parts:

• MICMUX: microphone input multiplexer

• MICADC: Σ∆ analog-to-digital converter

• DECIMATOR: decimates the incoming bit stream from

1 MHz to 40 kHz

• TXFILTER: band-pass filter for the digital transmit signal

and down-sampling

• TXPGA/LIM: fine-programmable gain for calibration,

limiter

• SidePGA: voice band sidetone programmable gain

amplifier.

Linearity of transmitter equipment, signal-to-total harmonic

distortion ratio according to “GSM recommendation

II.11.10 V.4.16.1”.

10.2.1 MICMUX

MICMUX is used to select between a differential signal at

pins MICP/MICN and a differential signal at pins

AUXMICP/AUXMICN.

Values are specified for a standard electret microphone

with a sensitivity of −64 ±3 dB for high gain or for an

external microphone with an amplifier sensitivity of

−26 ±3 dB (0 dB ≡ 1 V/0.1 Pa = 1 V/µbar; at 1 kHz).

10.2.2 MICADC

MICADC is a Σ∆ A/D converter which generates a 1 MHz

bitstream.

10.2.3 DECIMATOR AND TXFILTER

The DECIMATOR is a digital filter, which performs a signal

processing to a lower sampling rate at the output

compared to the input.

The bitstream with a sampling frequency of 1 MHz is

low-pass filtered and down-sampled to 40 kHz by a FIR

filter.

A digital high-pass filter and a digital low-pass filter (both

IIR filters) process the 14-bit input samples to achieve a

band-pass with a pass band from 300 to 3400 Hz. These

filters run on the on-chip voice band signal processor (see

Fig.7). It’s program is down-loaded into the instruction

memory (IRAM) via the CSI (see Table 26).

The output of the TXFILTER is down-sampled to a

sampling frequency of 8 kHz with a word length of 16 bits.

10.2.4 TXPGA

TXPGA adapts the analog signals coming from MICMUX

within a range of −30 to +6 dB. It is designed for calibration

purposes.

10.2.5 SIDEPGA

SidePGA loops part of the voice band transmit signal back

into the receive path. There are 64 gain steps from mute to

+6 dB.

10.3 Voice band digital circuitry

The voice band digital circuitry is responsible for

converting a 16-bit PCM signal at 8 kHz sample rate to and

from a 1-bit 1 MHz signal. It also contains a band-pass

filter for 300 to 3400 Hz and a sidetone engine. Various

volume settings are calculated inside this block. Figure 7

shows the block diagram of the voice band signal

processor.

1999 May 03

17

Share Link: