Analog Devices has unveiled a chip that shrinks the radio in GSM/GPRS cellular telephones to as little as 1.5 square centimetres.
The so-called Othello-G device supports full quad-band operation and integrates virtually all the necessary components for a complete cellular handset radio design such as voltage-controlled oscillators (VCOs) and the associated tank circuits, PLL loop filters, and power management. The only external components required for a complete radio design are the receive SAW (surface acoustic wave) filters, power amplifier, transmit/receive switch, and a few passives.
The device features four fully integrated programmable gain differential LNAs (low-noise amplifiers) for full quad-band (GSM850/900/ 1800/1900) support. It uses a single integrated LO (local oscillator) VCO (voltage control oscillator) for both receive and transmit circuits. The synthesizer lock times are optimized for GPRS applications up to and including class 12. To dramatically reduce the radio BOM, the synthesizer integrates a loop filter and incorporates a complete reference crystal calibration system.
The AD6548 Othello-G radio chip, which is available now, can be used to build a fully-functional reference design with approximately 75% fewer components than its previous version and enabling a complete quad-band radio that is 30% smaller than anything available on the market.