LMX2486 Series
1-GHz to 4.5-GHz delta-sigma low power dual PLL for RF personal communications
Manufacturer: Texas Instruments
Catalog
1-GHz to 4.5-GHz delta-sigma low power dual PLL for RF personal communications
Key Features
• Quadruple Modulus Prescaler for Lower DividsRF PLL: 16/17/20/21 or 32/33/36/37IF PLL: 8/9 or 16/17Advanced Delta Sigma Fractional Compensation12-Bit or 22-Bit Selectable FractionalModulusUp to 4th Order Programmable Delta-Sigma ModulatorImproved Lock Times and ProgrammingFastlock / Cycle Slip Reduction Which RequiresOnly a Single-Word WriteIntegrated Time-Out CounterWide Operating RangeLMX2486 RF PLL: 1.0 GHz to 4.5 GHzUseful FeaturesDigital Lock Detect OutputHardware and Software Power-Down ControlOn-Chip Crystal Reference Frequency DoublerRF Phase Detector Frequency Up to 50 MHz2.5-V to 3.6-V Operation With ICC= 8.5 mAQuadruple Modulus Prescaler for Lower DividsRF PLL: 16/17/20/21 or 32/33/36/37IF PLL: 8/9 or 16/17Advanced Delta Sigma Fractional Compensation12-Bit or 22-Bit Selectable FractionalModulusUp to 4th Order Programmable Delta-Sigma ModulatorImproved Lock Times and ProgrammingFastlock / Cycle Slip Reduction Which RequiresOnly a Single-Word WriteIntegrated Time-Out CounterWide Operating RangeLMX2486 RF PLL: 1.0 GHz to 4.5 GHzUseful FeaturesDigital Lock Detect OutputHardware and Software Power-Down ControlOn-Chip Crystal Reference Frequency DoublerRF Phase Detector Frequency Up to 50 MHz2.5-V to 3.6-V Operation With ICC= 8.5 mA
Description
AI
The LMX2486 device is a low-power, high performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL. The device is fabricated using TI’s advanced process.
With delta-sigma architecture, fractional spurs at lower offset frequencies are pushed to higher frequencies outside the loop bandwidth. The ability to push close in spur and phase noise energy to higher frequencies is a direct function of the modulator order. Unlike analog compensation, the digital feedback technique used in the LMX2486 is highly resistant to changes in temperature and variations in wafer processing. The LMX2486 delta-sigma modulator is programmable up to fourth order, which allows the designer to select the optimum modulator order to fit the phase noise, spur, and lock time requirements of the system.
Serial data for programming the LMX2486 is transferred through a three-line, high-speed (20-MHz) MICROWIRE interface. The LMX2486 offers fine frequency resolution, low spurs, fast programming speed, and a single-word write to change the frequency. This makes it ideal for direct digital modulation applications, where the N-counter is directly modulated with information. The LMX2486 is available in a 24-lead 4.0 × 4.0 × 0.8 mm WQFN package.
The LMX2486 device is a low-power, high performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL. The device is fabricated using TI’s advanced process.
With delta-sigma architecture, fractional spurs at lower offset frequencies are pushed to higher frequencies outside the loop bandwidth. The ability to push close in spur and phase noise energy to higher frequencies is a direct function of the modulator order. Unlike analog compensation, the digital feedback technique used in the LMX2486 is highly resistant to changes in temperature and variations in wafer processing. The LMX2486 delta-sigma modulator is programmable up to fourth order, which allows the designer to select the optimum modulator order to fit the phase noise, spur, and lock time requirements of the system.
Serial data for programming the LMX2486 is transferred through a three-line, high-speed (20-MHz) MICROWIRE interface. The LMX2486 offers fine frequency resolution, low spurs, fast programming speed, and a single-word write to change the frequency. This makes it ideal for direct digital modulation applications, where the N-counter is directly modulated with information. The LMX2486 is available in a 24-lead 4.0 × 4.0 × 0.8 mm WQFN package.
