LMX2364
LMX2364 is 2.6 GHz PLLatinum Fractional RF Frequency Synthesizer manufactured by National Semiconductor.
Description
The LMX2364 integrates a high performance 2.6 GHz fractional frequency synthesizer with a 850 MHz low power Integer-N frequency synthesizer. Designed for use in a local oscillator subsystem of a radio transceiver, the LMX2364 generates very stable, low noise control signals for UHF and VHF voltage controlled oscillators. It is fabricated using National’s high performance Bi CMOS process. The RF Synthesizer supports both fractional and integer modes. The N counter contains a selectable, quadruple modulus prescaler and can support fractional denominators from 1 to 128. A flexible, 4 level programmable charge pump supplies output current magnitudes ranging from 1 m A to 16 m A. Only a single word write is required to power up and tune the synthesizer to a new frequency. High performance Fast Lock™ technology makes the LMX2364 an excellent choice for applications requiring aggressive lock time while maintaining excellent phase noise and spurious performance. The bination of the improved Fast Lock circuitry, the enhanced fractional pensation engine, and the programmable charge pump architecture gives the designer maximum freedom to optimize the performance of the synthesizer for the target application. Integrated timeout counters greatly simplify the programming aspects of Fast Lock. These timeout counters reduce the demands on the microcontroller by automatically disengaging Fast Lock after a perscribed number of reference cycles of the phase detector. The IF synthesizer includes a fixed 8/9 dual modulus prescaler, a two level programmable charge pump, and dedicated Fast Lock circuitry with an integrated timeout counter. The LMX2364 offers many performance enhancements over the LMX2354. Improvements in the fractional pensation make the spurs on the LMX2364 approximately 6 d B better in a typical application. The higher and more flexible fractional modulus bined with the higher charge pump currents result in phase noise improvements on the order of 10 d B. The cycle...
