Out in Front

PLL family slashes power consumption, reduces phase noise

National's LMX23x6 trio of single-PLL devices and LMX233xL quintet of dual-PLL devices target personal-communications-system, direct-broadcast-satellite, global-positioning-system, and other applications in which portability and power consumption without performance shortfall are critical. The three single PLLs, in 16-lead TSSOPs, feature maximum operating-frequency and current-consumption pairings of 0.5 GHz/1.2 mA, 1.2 GHz/2 mA, and 3 GHz/3.5 mA. They operate with supplies of 2.3 to 5.5V. Phase-noise floor is –167 dBc/Hz. These ICs include a digital lock-detect output and multispeed locking. This feature reduces lock time by as much as 35% when you activate an internal timing function. This function switches both loop filter and phase-detector gain from their wider, faster settling bandwidth mode to a narrower bandwidth mode that improves noise performance. Prices for the single PLLs range from $3.45 to $4.95 (1000), depending on speed.

The five dual PLLs for RF/IF designs (four in 20-lead TSSOPs, one in a 16-lead package) offer maximum frequency pairings of 2.5 GHz/510 MHz, 2.0 GHz/510 MHz, 1.2 GHz/510 MHz, 1.1 GHz/1.1GHz, and 2.0 GHz/1.1 GHz. Their phase-noise floor is –169 dBc/Hz. Supply currents for these 2.7 to 5.5V devices range from 3 to 5 mA; prices range from $4.50 to $6.95 (1000). —by Bill Schweber

National Semiconductor Corp, Sunnyvale, CA. (800) 272-9959, http://www.national.com.