Integrated PLL/VCO chip cuts CDMA designs to size

National Semiconductor has developed the world's first family of integrated circuits that combine PLL and VCO functions in a single chip optimised for CDMA mobile handsets.

National Semiconductor has developed the world's first family of integrated circuits that combine PLL and VCO functions in a single chip optimised for CDMA mobile handsets.

By integrating the phase locked loop (PLL) and voltage controlled oscillator (VCO) functions into a single frequency synthesiser circuit, National's design reduces the board space required by 67% over designs that use discrete PLL and VCO circuits.

"As mobile handsets continue to shrink in size while adding more features, board space or "footprint" of circuit elements becomes a more critical design factor", said William Weiss, Wireless Communications Marketing Manager.

"National Semiconductor's integration of different RF circuit blocks enables handset manufacturers to meet the ever-increasing demand for more functionality in a smaller form factor".

The first four members of National's PLLatinum integrated PLL/VCO family are: the LMX2502 for PCS-band CDMA handsets and data systems; the LMX2512 for cellular-band CDMA handsets and data systems; the LMX2522 for PCS-band CDMA handsets containing global positioning system capability; and the LMX2532 for cellular-band CDMA handsets containing global positioning system capability.

All four are available now.

A fifth member of the family currently shipping in preproduction volume: the LMX2505, is the world's first integrated dual-band PLL and VCO for PDC handsets.

The LMX2505 will be in in full production in April 2003, followed by additional integrated PLL and VCO products that meet other worldwide mobile handset standards.

Several major handset manufacturers already have designed members of the LMX25xx family into mobile handsets to be brought to market in 2003, attributing their choice to the 67% savings in printed circuit board space.

This opens up critically needed board space for other functions in their latest mobile handsets, allowing them to include advanced differentiating features such as an integrated camera, MP3 player, Bluetooth, or other additional features.

All of National's integrated PLL + VCO family are high performance, highly integrated frequency synthesiser systems on a chip that elevate PLL technology to a new level by combining the PLL, VCO and loop filter functions into a single circuit that meets the rigorous RF specifications required by CDMA and PDC mobile handsets.

The LMX25xx family provides all the features of National's PLLatinum PLL technology to generate high quality local oscillator signals for mobile handset radio transceivers.

They feature low phase noise of -138dBc/Hz at 1.25MHz offset from 1.6GHz, and -139dBc at 900kHz offset from 1GHz.

They also feature fast lock time of 600us, low spurs, 2.7 to 3.3V operation, and low power consumption, all in a small 5 x 5 x 0.75mm 28-pin leadless leadframe package (LLP).

The LMX2502 and LMX2512 are available now, priced at $2.66 per unit in 1000-unit quantities.

The LMX2522 and LMX2532 are available now priced at $3.19 per unit in 1000-unit quantities.

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