The document introduces Circuit Note CN-0232 Circuits from the Lab™ reference circuits, which are engineered and tested for quick and easy system integration to help solve today's analog, mixed-signal, and RF design challenges. The document also mentions the connected/referenced devices, including ADF4350 fractional-N PLL synthesizer with integrated VCO and ADF4153 fractional-N PLL frequency synthesizer. It emphasizes that standard engineering practices have been employed in the design and construction of each circuit, and their function and performance have been tested and verified in a lab environment. However, users are still responsible for testing the circuit and determining its suitability and applicability for their use and application. In addition, Analog Devices shall not be liable for any direct, indirect, special, incidental, consequential or punitive damages due to any cause whatsoever connected to the use of any Circuits from the Lab circuits.
This document presents a reference circuit designed to minimize spurious outputs in RF systems. It utilizes the ADF4350 Fractional-N PLL Synthesizer with an Integrated VCO in conjunction with an external ADF4153 Fractional-N PLL Frequency Synthesizer. The configuration isolates the PLL circuitry from the VCO circuitry to reduce feed-through and improve spurious performance.
The note details the circuit function, benefits, and specific variations of PLLs that can be selected. It provides a functional block diagram and a test setup using evaluation boards (EVAL-ADF4350EB2Z and EVAL-ADF4153EBZ1). The document includes initialization and frequency update procedures for the software programming required to operate the circuit.
| Frequency Range | 137.5 MHz to 4400 MHz |
|---|---|
| VCO Frequency Range | 2.2 GHz to 4.4 GHz |
| VCO Band Coverage | approximately 700 MHz |
| ADF4157 Frequency Resolution | <1 Hz |
Using an external PLL improves spurious performance and allows for increased frequency resolution.
The ADF4150 PLL is software compatible with the ADF4350, easing the software programming sequence.
The evaluation requires the EVAL-ADF4350EB2Z and EVAL-ADF4153EBZ1 boards, a 5.5 V power supply, an R&S SMA 100A signal generator, and an R&S FSUP26 spectrum analyzer.