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ADI touts 'tightest' integrated 3G transceivers

Posted: 15 Feb 2007 ?? ?Print Version ?Bookmark and Share

Keywords:transceiver CMOS 3G? W-CDMA? ADI Othello-3 radio? RF GSM Edge?

Analog Devices has launched the latest version of its direct conversion Othello radio architecture line at the 3GSM World Congress.

The company says the single chip device is the tightest integrated transceiver for 3G phones using the W-CDMA air interface.

Not surprisingly dubbed Othello-3, the CMOS RF radio was designed to cover all frequency bands except that reserved for satellite operation above 2.4GHz.

As with earlier versions of the Othello architecture, almost everything is on chip and, according to Doug Grant, director of business development at the wireless group of ADI, "that has meant we have achieved a typically 50 percent reduction in board area compared to competing devices as well as major reductions in BOM."

The board area is 5cm? for an Edge/W-CDMA transceiver.

Lower noise
In particular , Grant points to new transmit modulators that offer 10dB lower noise than the previous best on the transmit side and high linearity RF mixers that eliminate RX interstage SAW filters on the receiver end.

"The greater innovations are packed into the transmitter side including the use of a novel topology for the transmit modulator which achieves just -163dBc/Hz/noise at 190MHz offset," said Grant.

ADI is making the transceiver in 0.18?m CMOS, with the Othello-3 replacing a part offered for phone developers that was based on two chips made in RF CMOS.

The company already has versions of the Othello that support handsets designed for Edge (Othello-E) and GSM/GPRS (Othello-G). All use direct polar modulation to increase power amplifier efficiency.

Quad-band operation
Othello-3 supports full quad-band operation and integrates voltage-controlled-oscillators and the associated tank circuits, loop filters and power management circuitry.

The receiver section includes single-ended low-noise amplifiers for two high bands (1710MHz to 2170MHz) and one low band (824MHz to 960MHz). Direct-downconverting quadrature mixers driven by an on-chip fractional PLL synthesizer deliver baseband in-phase and quadrature signals to a variable-gain amplifier (VGA) and programmable low-pass filter stages with DC offset correction.

Grant said the device is being designed in to 3G handsets, but would not name its initial customers for the part, known as the AD6551 and which comes in a 6-by-6mm 40-lead lead-frame CSP.

He added that phones with Othello-3 would be shipping by 2H of this year.

- John Walko
EE Times Europe




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