LMX2364  Product Folder

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 BiCMOS 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 mA to 16 mA. Only a single word write is required to power up and tune the synthesizer to a new frequency.

High performance FastLock™ technology makes the LMX2364 an excellent choice for applications requiring aggressive lock time while maintaining excellent phase noise and spurious performance. The combination of the improved FastLock circuitry, the enhanced fractional compensation 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 FastLock. These timeout counters reduce the demands on the microcontroller by automatically disengaging FastLock 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 FastLock circuitry with an integrated timeout counter.

The LMX2364 offers many performance enhancements over the LMX2354. Improvements in the fractional compensation make the spurs on the LMX2364 approximately 6 dB better in a typical application. The higher and more flexible fractional modulus combined with the higher charge pump currents result in phase noise improvements on the order of 10 dB. The cycle slip reduction circuitry of the LMX2364 is both easy to use and effective in reducing cycle slipping and allows one to use very high phase detector frequencies without degrading lock times.

Serial data is transferred to the device via a three-wire interface (DATA, LE, CLK). The low voltage logic interface allows direct connection to 1.8 Volt and 3.0 Volt devices. Supply voltages from 2.7V to 5.5V are supported. Independent charge pump supplies for each synthesizer allows the designer to optimize the bias level for the selected VCO. The LMX2364 consumes 5.0 mA (typical) of current in integer mode and 7.2 mA (typical) in fractional mode. The LMX2364 is available in a 24 Pin Ultra Thin CSP package and 24 Pin TSSOP Package.

• RF Synthesizer supports both Fractional and Integer Operating Modes
• Pin Compatible upgrade for LMX2354
• 2.7V to 5.5V operation
• Pin and programmable power down
• Fractional N divider supports fractional denominators ranging from 1 through 128
• Supports Integer Mode Operation
• Programmable charge pump current levels RF: 4 level, 1 - 16 mA IF: 2 level, 100/800 uA
• FastLock Technology with integrated timeout counters
• Digital filtered & analog lock detect output
• FastLock Glitch Reduction Technology
• Enhanced Low Noise Fractional Compensation Engine
• Low voltage programming interface allows direct connection to 1.8V logic

• Digital Cellular
• GPRS
• IS-136
• GAIT
• PDC
• EDGE
• CDMA
• Zero blind slot TDMA systems
• Cable TV Tuners (CATV)