Technology news from Philips Semiconductors

Citation

(2001), "Technology news from Philips Semiconductors", Microelectronics International, Vol. 18 No. 1. https://doi.org/10.1108/mi.2001.21818aad.006

Technology news from Philips Semiconductors

Technology news from Philips Semiconductors

Keywords: Philips, Synthesizers

Philips Semiconductors has introduced a new generation of radio frequency (RF) synthesizer technology. Philips Semiconductors' new Sigma-Delta Fractional-N Synthesizers will dramatically improve performance in high-bandwidth digital wireless products including cell phones, cordless handsets, pagers and cellular base stations.

Philips claims that it has developed a sigma-delta based fractional-N RF-synthesizer with extremely low phase noise – 103dBc/Hz. By simultaneously delivering low phase noise and fast acquisition time, Philips Semiconductors' new RF synthesizer technology is suited to meet the requirements for the emerging 2.5 and third generation digital wireless services, including General Packet Radio Service (GPRS) and High Speed Circuit Switched Data (HSCSD) of the Global System for Mobile Communications (GSM) standard, as well as IS-95B and C, 1-3 xRTT of CDMA standard and upcoming UMTS systems.

The new technology will be part of Philips Semiconductors' "8-family" of sigma-delta fractional-N synthesizers, which can operate up to 2.5GHz. These devices are designed for wireless applications that require low phase noise, fast switching speeds, ultra fine frequency resolution and low current. The new synthesizer chips will feature a main divider with integer ratios from 33 to 509 in conjunction with a second order programmable sigma-delta-modulator that provides a frequency resolution of 1/2²³ times the phase detector frequency. The phase detector (PD) on these new chips operates with input frequencies up to 30MHz. The devices will also have multiple integrated charge pumps for loop filter design flexibility and an auxiliary integer divider that operates from 80 to 750MHz. All this is enclosed in a 4mm x 4mm 24-pin BCC package.

The phase noise performance of Philips Semiconductors' new RF IC technology measures –103dBc/Hz with a VCO centre frequency of 950MHz and a phase detector frequency of 20MHz – reportedly the lowest in the industry. Furthermore, the sigma-delta noise shaping significantly reduces the fractional spurs experienced using analog spur compensation methodology. The trade-off for better phase noise performance, based on high phase detector frequencies, is a larger capacitor in the loop filter (typically in the range of hundreds of nanofarads): and the charge-up time that goes along with it. Consequently, Philips Semiconductors has implemented a loop filter pre-charging architecture that increases the dynamic charge by 17 x during acquisition. Therefore, fast lock times are maintained even with large capacitors.

Power consumption (battery life) and efficient spectral usage (frequency planning) continue to be key issues with the wireless and portable appliances industries. Philips Semiconductors addresses these issues directly with its fully integrated sigma-delta modulator which provides more flexibility in frequency planning with an extremely low current consumption of 7.5mA typical (main and auxiliary loops in lock).

Philips Semiconductors' new sigma-delta fractional-N synthesizers will be introduced as a pin for pin compatible alternative to previous analog compensated fractional-N synthesizers for applications where superior phase noise, spur performance, and frequency resolution are needed. Beta samples are under co-evaluation with a select group of strategic customers and will be available to general customers in Q1-01, together with demo-boards, software and application notes.