Summary of LTC6948 – Ultralow Noise 0.37GHz to 6.39GHz Fractional-N Synth0esizer with Integrated VCO
The LTC6948 is a low-noise Fractional-N PLL with integrated VCO covering 0.37GHz to 6.39GHz. It features an advanced 4th-order ΔΣ fractional divider with low spurs, ultralow-noise charge pump and PFD, programmable output divider (1–6), high reference input bandwidth, fast switching, and FracNWizard software support, delivering excellent phase noise and integer-boundary spurious performance for high-performance frequency synthesis.
Parts used in the LTC6948 Project:
- LTC6948 integrated Fractional-N PLL with VCO
- Reference input source (up to 425 MHz)
- External power supply (per LTC6948 requirements)
- Output load or buffer circuitry
- Control interface to program fractional divider and VCO divider
- FracNWizard software (for design and programming)
Features
- 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
Typical Application
Description
The LTC®6948 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.
For more detail: LTC6948 – Ultralow Noise 0.37GHz to 6.39GHz Fractional-N Synthesizer with Integrated VCO
- What frequency range does the LTC6948 cover?
The LTC6948 covers 0.37GHz to 6.39GHz. - Does the LTC6948 include an integrated VCO?
Yes, the LTC6948 includes a fully integrated VCO. - What output divider options are available?
The output divider is programmable from 1 to 6 with 50% duty cycle. - What is the maximum reference input frequency?
The reference input frequency can be up to 425 MHz. - Does the LTC6948 use a Delta-Sigma modulator and does it produce spurs?
It uses a 4th order ΔΣ modulator designed to provide exceptionally low spurious levels; the device notes no Δ-Σ modulator spurs. - What performance does the LTC6948 offer for phase noise?
It provides very low phase noise including a −226 dBc/Hz normalized in-band floor and −157 dBc/Hz wideband output floor, plus −274 dBc/Hz normalized in-band 1/f noise. - Is fast frequency switching supported?
Yes, the LTC6948 supports fast frequency switching. - Does the LTC6948 provide output mute functionality?
Yes, it includes output buffer muting. - Is software support available for design with the LTC6948?
Yes, FracNWizard software design tool support is available.
