UAA2062 Просмотр технического описания (PDF) - Philips Electronics

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UAA2062

Analog cordless telephone IC

Philips Electronics 

Philips Semiconductors

Analog cordless telephone IC

Product specification

UAA2062

The TX baseband

This section covers the TX audio path from pins MICI to

TXO.

The microphone amplifier is an inverting operational

amplifier whose gain can be set by external resistors. The

input signal at pin MICI and the output signal at pin MOCO

are both AC-coupled. The non-inverting input is connected

to the internal reference voltage VB. External resistors are

used to set the gain and frequency response.

The TX baseband has a compressor with the

characteristic shown in Fig.9. The Automatic Level Control

(ALC) provides a ‘soft’ limit to the output signal swing as

the input voltage increases slowly (i.e. a sine wave is

maintained at the output). A hard limiter clamps the

compressor output voltage at 1.26 V (p-p). The ALC and

the hard limiter can be disabled via the microcontroller

interface. The hard limiter is followed by a mute circuit.

The TX gain is digitally programmable in 32 steps of

0.5 dB.

handbook, full pagewidth

MICI

14

MICO

13

microphone

amplifier

CCAP

11

ALC

CMPI

12

compressor

hard limiter

TX mute

TXO

6

FCA125

TX gain

Fig.8 TX baseband schematic diagram.

handbook, full pagewidTthXO

(dBV)

0

−10

− 20

− 30

− 40

− 60

VCMPI = −4 dBV; VTXO = −1.26 V(p-p)

(hard limiting signals)

VCMPI = −2.5 dBV

VTXO = −11.5 dBV

− 20

VCMPI = −16 dBV; VTXO = −13 dBV

− 30

(slowly changing ALC signals)

− 50

− 40

− 30

− 20

−10

0

CMPI (dBV)

FCA126

Fig.9 Compressor characteristic.

2000 Aug 10

11

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