UAA3522 データシートの表示（PDF） - Philips Electronics

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UAA3522

Low power dual-band GSM transceiver with an image rejecting front-end

Philips Electronics 

Philips Semiconductors

Low power dual-band GSM transceiver

with an image rejecting front-end

Objective specification

UAA3522HL

FEATURES

• Dual-band application for Global System for Mobile

communication (GSM) and Digital Cellular

communication Systems (DCS)

• Low noise and wide dynamic range single Intermediate

Frequency (IF) transceiver

• More than 30 dB on-chip image rejection in the receiver

• More than 60 dB gain control range

• I/Q demodulator with high performance integrated

baseband channel filter

• High precision I/Q modulator

• Transmit modulation loop architecture including offset

mixer and phase detector

• Dual Phase-Locked Loop (PLL) with on-chip IF Voltage

Controlled Oscillator (VCO)

• Fully differential design minimizing cross-talk and spurii

• 3-wire serial bus interface

• Functional down to 2.7 V and up to 3.3 V

• LQFP48 package.

APPLICATIONS

• GSM 900 MHz hand-held transceiver

• GSM/DCS dual-band solution with the UAA2077CM

(down to 3.2 V) or UAA2077TS/D (down to 2.7 V).

GENERAL DESCRIPTION

The UAA3522HL integrates the receiver and most of the

transmitter section of a GSM hand-held transceiver. It also

integrates the receiver IF and the transmitter section of a

DCS transceiver.

The receiver comprises an RF and an IF section. The RF

(GSM) front-end amplifies the aerial signal, converts the

chosen channel frequency to an IF of 200 MHz, and also

provides more than 30 dB of image suppression. Some

selectivity is provided at this stage by an off-chip bandpass

pre-filter. The IF section further amplifies the chosen

channel, maintains the gain at the required level,

demodulates the signal into I and Q components, and

provides channel selectivity at a baseband stage using a

high performance integrated low-pass filter. The IF gain

can be varied over a range of more than 60 dB. The offset

at the I and Q outputs can be cancelled out by software

using the 3-wire serial programming bus.

The input Low Noise Amplifier (LNA) can be switched off

via the bus to allow accurate calibration in the offset

cancellation mode.

The transmitter comprises a high precision I/Q modulator

and modulation loop architecture. The I/Q modulator

converts the baseband modulation frequency to the

transmit IF. The modulation loop architecture, which

includes an on-chip offset mixer and phase detector,

controls an external transmit RF VCO which converts the

transmit modulated IF signal to RF.

A receive RF VCO provides the Local Oscillator (LO)

signal to the image rejection mixers in the RF receiver. An

IF VCO provides the LO signal to the I/Q demodulator and

I/Q modulator in the receiver and transmitter sections

respectively.

The frequencies of the RF VCO and the IF VCO are set by

internal PLL circuits, which are programmable via the

3-wire serial bus. The RF and IF PLL comparison

frequencies are 200 kHz and 1 MHz respectively, derived

from a 13 MHz reference signal which has to be supplied

externally. The quadrature RF LO signals required by the

image rejection mixers are obtained using on-chip

Resistor Capacitor (RC) networks. The quadrature IF LO

signals required by the I/Q modulator and I/Q demodulator

are obtained by dividing the frequency of the IF VCO

signal.

The IC can be powered on in either receiver (RX),

transmitter (TX) or synthesizer (SYN) operating mode

depending on the logic level at pins RXON, TXON and

SYNON, respectively. Alternatively, an operating mode

can be selected by software using the 3-wire serial

programming bus. In RX or TX mode, only those sections

of the IC which are required are switched on.

The GSM or DCS band is selected by the 3-wire serial

programming bus. When activating RX mode for DCS

applications, the receiver RF section can be disabled by

software so that only the receiver IF section is

powered-on.

The SYN mode is used to power-on the synthesizer prior

to activating the RX or TX mode. In SYN mode, some

internal LO buffers are also powered-on to minimize the

‘pulling’ effect of the VCO when either the receiver or the

transmitter are switched on.

2000 Feb 18

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