Features and Benefits
- Low Noise Fractional-N PLL with Integrated VCO
- No Δ-Σ Modulator Spurs
- 18-Bit Fractional Denominator
- –226 dBc/Hz Normalized In-Band Phase Noise Floor
- –274 dBc/Hz Normalized In-Band 1/f Noise
- –157 dBc/Hz Wideband Output Phase Noise Floor
- Excellent Integer Boundary Spurious Performance
- Output Divider (1 to 6, 50% Duty Cycle)
- Output Buffer Muting
- Reference Input Frequency Up to 425MHz
- Fast Frequency Switching
- FracNWizard™ Software Design Tool Support
The LTC6948 is a high performance, low noise, 6.39GHz phase-locked loop (PLL) with a fully integrated VCO, including a reference divider, phase-frequency detector (PFD), ultralow noise charge pump, fractional feedback divider, and VCO output divider.
The fractional divider uses an advanced, 4th order ΔΣ modulator which provides exceptionally low spurious levels. This allows wide loop bandwidths, producing extremely low integrated phase noise values.
The programmable VCO output divider, with a range of 1 through 6, extends the output frequency range.
- Wireless Basestations (LTE, WiMAX, W-CDMA, PCS)
- Microwave Data Links
- Military and Secure Radio
- Test and Measurement
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (5)
Demonstration circuit 1959B features the LTC6948, an Ultralow Noise and Spurious Fractional-N Synthesizer with Integrated VCO.
There are four options of the DC1959B, one for each version of the LTC6948. Table 1 summarizes the available DC1959B options.
The DC1959B provides 50Ω SMA connectors for the reference frequency input fREF (REF+IN) and the differential RF output (RF+ and RF–).
A DC590 USB serial controller board is used for SPI communication with the LTC6948, controlled by the supplied FracNWizard™ software.
Demonstration Circuit 2429A is a PLL/VCO Supply and Reference Frequency Board that features the LT3042, an ultralow noise and ultrahigh PSRR RF linear regulator. When powered from a 6V to 20V lab or wall wart supply, the DC2429A produces four ultralow noise supplies using seven LT3042s. These supplies include a fixed 3.3V/800mA supply (four LT3042's in parallel), a fixed 5V/200mA supply, a fixed 3.3V/200mA supply that powers an onboard 100MHz ultralow jitter crystal oscillator, and an adjustable voltage (2.5V to 15V), 200mA supply ideal for powering external VCOs. The DC2429 ensures PLL/VCO evaluation meets data sheet performance.
Demonstration circuit 1959A features the LTC6948, an Ultralow Noise and Spurious Fractional-N Synthesizer with Integrated VCO. There are four options of the DC1959A, one for each version of the LTC6948. Table 1 summarizes the available DC1959A options.
Software & Systems Requirements
Tools & Simulations
Linduino is Analog Devices’ Arduino compatible system for developing and distributing firmware libraries and example code for our integrated circuits. Each Linduino-supported product includes an example main program, defined in the LTSketchbook/Part Number folder and driver code, defined in the LTSketchbook/libraries folder.
ADIsimPLL enables the rapid and reliable evaluation of new high performance PLL products from ADI. It is the most comprehensive PLL Synthesizer design and simulation tool available today. Simulations performed include all key non-linear effects that are significant in affecting PLL performance. ADIsimPLL removes at least one iteration from the design process, thereby speeding the design- to-market.
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ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
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The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.