With the FS2 Frequency Synthesizer (AP4007A), a microwave signal source in the form of a flange-mount module with a frequency range from 8 kHz to 20 GHz, Keysight provides a drop-in replacement for the National Instruments QuickSyn FSW-0020 frequency synthesizer, which was phased out a few years ago. Designed to seamlessly replace the QuickSyn FSW-0020, the FS2 Frequency Synthesizer enables an uncomplicated transition for QuickSyn users and ensures uninterrupted performance.
Elevated frequency synthesizer performance
The FS2 Frequency Synthesizer preserves the best attributes of the FSW-0020 while implementing a host of enhanced capabilities. The FS2 Frequency Synthesizer is an instrument-grade signal source that achieves performance that is on par with or surpasses the performance of the FSW-0020. The heart of the FS2 Frequency Synthesizer’s exceptional performance lies in the integration of a high-quality oven-controlled crystal oscillator (OCXO) as an internal reference. The OCXO delivers low close-to-carrier phase noise, establishing excellent long-term frequency stability. Capitalizing on proprietary signal synthesis techniques, the FS2 Frequency Synthesizer integrates a low noise VCO with phase detectors, frequency dividers, and multipliers. This architecture results in a signal source with what we believe is the lowest phase noise among all compact frequency synthesizers currently available. The measured single sideband (SSB) phase noise of the FS2 Frequency Synthesizer signal source at 10 GHz is shown in Figure 1.
Figure 1. SSB phase noise of FS2 Frequency Synthesizer at 10 GHz.
To minimize non-harmonic signal components, the FS2 Frequency Synthesizer uses a two-stage frequency synthesis scheme. In the initial stage, it generates a finely tuned reference frequency that deliberately avoids an integer multiple of the OCXO. The second stage employs this reference frequency for octave frequency range synthesis, bolstered by level conditioning and filtering. This architecture results in a -70 dBc level of non-harmonic frequency components across the spectrum from 0.1 to 20 GHz. This is complemented by direct digital synthesis technology, offering frequency resolution down to 1 mHz.
The FS2 Frequency Synthesizer contains a whole host of other features that improve performance and user experience. It has an automatic level control mechanism that delivers power level setting accuracy of ± 0.3 dB, surpassing the QuickSyn capabilities. The FS2 Frequency Synthesizer harnesses multiple switched VCOs within the base frequency octave to provide a fast frequency switching capability, with switching typically occurring within 20 μs. This approach significantly improves frequency tuning times, ensuring responsiveness that matches the demands of multiple applications. The FS2 Frequency Synthesizer also boasts the ability to support analog modulations, further enhancing its versatility in a diverse set of applications.
Keysight maintains a commitment to a holistic user experience. The module’s energy-efficient design enables passive cooling when correctly mounted on heat-dissipating surfaces. The device is provisioned with comprehensive graphical user interface (GUI) control software, facilitating seamless control. USB, LAN, and SPI ports enrich its communication capabilities, catering to diverse user preferences.
Benchmarking excellence: A comparative overview
The following table presents a concise comparison between the Keysight FS2 Frequency Synthesizer and NI’s FSW-0020. It succinctly highlights the FS2 Frequency Synthesizer’s performance enhancements and reinforces its position as an innovative replacement for the FSW-0020.
Technical comparison of NI FSW-0020 and Keysight FS2 Frequency Synthesizer (model AP4007A)
Parameter
NI FSW-0020
Keysight FS2 Frequency Synthesizer
(Model AP4007A)
Frequency range
0.2 to 20 GHz
8 kHz to 20 GHz
Switching speed
100 μs (list sweep)
200 μs (over SPI)
20 μs (list sweep)
200 μs (over SPI)
Power range
-10 to +13 dBm @ > 0.5 GHz
-25 to +16 dBm @ >1 GHz
Level accuracy
±2.0 dB
±0.3 dV
Phase noise @ 100 Hz / 10 kHz / 1 MHz from 10 GHz
-83 / -122 / -126 dBc/Hz
-95 / -126 / -130 dBc/Hz
Harmonics / Non-harmonics
-35 / -70 dBc @ < 0.5 GHz
-50 / -70 dBc @ > 0.1 GHz
Modulations
Pulse, AM / FM
Pulse, AM / FM
Reference in / out
10 MHz
10 MHz, 100 MHz, 1 GHz
Communication ports
SPI, USB
SPI, USB, Ethernet
Power supply and consumption
12 VDC / 20 W
12 – 30 VDC / 24 W
Unleashing possibilities
The FS2 Frequency Synthesizer’s versatility extends to a wide spectrum of applications. It serves as a precision system clock, a high purity local oscillator for analog mixers and digital modulators, and a reliable microwave source for spectroscopic systems. Its fast-switching prowess makes it a solution that is well-suited for fast frequency hopping, radar signal generation, and mission-critical electronic warfare applications. Notably, former NI QuickSyn frequency synthesizer users now have an exceptional replacement that ensures product availability and continuity without the burden of costly redesigns.
The FS2 Frequency Synthesizer is positioned as a top choice for RF and microwave engineers and scientists. It encapsulates the trifecta of high signal purity, precise setting capabilities, and fast switching capabilities. As the industry continues its quest for excellence, the FS2 Frequency Synthesizer stands at the forefront, ushering in a new era of microwave signal sources that empower innovation.
Interested in more information about Keysight products?