Direct-Conversion GSM ICs Slash Phones' Size And Cost

The Othello GSM radio chipset incorporates a direct-conversion receiver that enables a dual-band radio to be implemented in a total board area of less than 9 cm² with less than 90 components, along with a corresponding dramatic cost reduction. The direct-conversion approach effectively eliminates all IF downconversion stages, extra oscillators and extra filtering.The set consists of two chips. One, the AD6523, is a GSM-path LNA that includes support circuits such as a low-dropout regulator. The other, the AD6524, is a complete fractional-N synthesizer (including crystal oscillator). Use of a fractional-N synthesizer is necessary to achieve the fast lock times that allow for standby time improvement.