3G transceiver does away with SAW filters

CMOS RF transceiver provides a complete solution for 3G mobile terminals based on the W-CDMA air interface standard.

Analog Devices has unveiled the latest addition to its award-winning family of Othello radios, the Othello-3.

This CMOS RF transceiver provides a complete solution for 3G mobile terminals based on the W-CDMA air interface standard.

Leveraging ADI's Othello direct-conversion architecture and an innovative low-noise transmitter, the Othello-3 (AD6551) transceiver eliminates the need for transmit-path surface acoustic wave (SAW) filters.

In addition to simplifying the RF section in 3G mobile terminals, Othello-3 reduces board space by 40% over competing solutions - key drivers to delivering smaller, more cost-effective 3G handsets.

The Othello-3 transceiver is currently being demonstrated at the 3GSM World Congress in Barcelona (Booth 1C58 at Hall 1).

"Following on the success of our Othello-G chipset, which significantly decreased the size of the radio in GSM/GPRS, we are now able to reduce board space in W-CDMA terminals to a mere 5 square centimetres - less than one square inch", said Christian Kermarrec, Vice President, RF and Wireless Systems, Analog Devices.

"Our innovative technique to reducing the component count of a typical RF front end translates into lower cost, easier to implement solutions, thereby driving the proliferation of highly-integrated, feature-rich, W-CDMA handsets".

According to research and consulting firm Strategy Analytics, the worldwide market for W-CDMA handsets is expected to nearly double, from 90 million units to 161 million units in 2007.

Othello-3 expands ADI's portfolio of award-winning direct-conversion radios, which includes Othello-E (supporting Edge) and Othello-G (supporting GSM/GPRS).

Othello-3 supports full quad-band operation and integrates virtually all the necessary components for a complete cellular handset radio design, such as voltage-controlled-oscillators and the associated tank circuits, loop filters and power management circuitry.

The device also features a low-noise transmitter architecture, eliminating the need for transmit-path SAW filters, which are usually needed to prevent transmitter noise from interfering with the receiver in full-duplex operation.

In doing so, Othello-3 significantly reduces cost and board space compared with existing RF transceiver solutions and complements the Analog Devices SoftFone-W baseband chipset for W-CDMA handsets.

The Othello-3 transceiver provides a complete transmit/receive solution for W-CDMA-based mobile terminals.

The receiver section includes high-performance single-ended low-noise amplifiers for two high bands (1710 to 2170MHz) and one low band (824 to 960MHz).

Direct-downconverting quadrature mixers driven by an on-chip fractional PLL synthesiser deliver baseband in-phase and quadrature signals to a variable-gain amplifier (VGA) and programmable low-pass filter stages with dc offset correction.

The transmitter section consists of a fractional PLL synthesiser, high performance VGAs and quadrature modulators for high- and low-band outputs, as well as a root-mean-square (RMS) RF power detector and on-chip digital-to-analogue convertor (DAC) for power amplifier control.

Othello-3 (AD6551) is sampling now in a 6 x 6mm 40-lead lead-frame chip scale package.

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