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RF PLL： 16/17/20/21 or 32/33/36/37
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IF PLL： 8/9 or 16/17
Advanced sigma-delta fraction compensation
- 12-bit or 22-bit decimal modulus is available
- Up to the 4th order programmable delta-sigma modulator
Features to improve lock-up time and programming
- Fastlock/weekly jump reduction
- Comprehensive timeout counter
- Write a word to change the frequency with Fastlock
Wide operating voltage range
- LMX2487E RF PLL: 3.0 GHz to 7.5 GHz
Practical features
- Digital lock detection output
- Hardware and software power-down control
- The on-chip crystal reference frequency is multiplied.
- RF comparison frequencies up to 50 MHz
- 2.5 to 3.6 volts operation with ICC= 8.5 mA 3.0 V
illustrate
The LMX2487E is a low-power, high-performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL. It is manufactured using an advanced process manufactured by National Semiconductor.
With the delta-sigma architecture, fractional spurs with lower offset frequencies are pushed to higher frequencies with external loop bandwidth. The ability to push in boost and phase noise energy close to higher frequencies is the modulator's command-indicating function. With analog compensation, digital feedback technology used in the LMX2487E has high resistance to temperature changes and wafer processing variations. The LMX2487EΔ-Σ modulator is programmable to the fourth order, which allows the designer to select the best modulator to accommodate phase noise, spur, and lock system time requirements.
For programming LMX2487E serial data transmission via a three-wire high-speed (20 MHz) MICROWIRE Interface. The LMX2487E offers fine frequency resolution, low spurs, fast programming speed, and one-word write to change frequency. This makes it ideal for direct digital modulation applications where the N counter is modulated directly with the information. The LMX2487E is available in 24 lead 4.0 × 4.0 x 0.8 mm LLP package.
apply
- Cell phones and base stations
- Direct digital modulation applications
- Satellite and cable tuner
- Wireless LAN standard
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