Sweep Oscillator Plug-Ins vs. Synthesized Signal Generators: Analog Sweeping and Phase Noise
Filed under Plug-ins
This guide explores the design and application differences between analog sweep oscillator plug-ins and synthesized signal generators. Historically, RF and microwave engineers relied on modular sweep oscillators, such as the Keysight Technologies (Agilent HP) 83592A, to perform broadband sweep testing. We analyze how continuous analog sweeps compare against the step-based architectures of modern synthesizers. This comparison focuses on frequency tuning, spectral characteristics, and performance trade-offs in applications like scalar network analysis. This guide is intended for engineers and technical buyers evaluating classical sweep testing methods versus synthesized instrumentation.
- Frequency Range
- 10 MHz to 20 GHz
- Maximum Leveled Power
- +10 dBm
- Power Flatness
- ±0.9 dB
- Source SWR (8 to 20 GHz)
- <1.9
Continuous Analog Sweeps vs. Synthesized Steps
Analog sweep oscillators provide a continuous, voltage-tuned sweep across their frequency range. For example, the Keysight Technologies (Agilent HP) 83592A covers a wide range from 10 MHz to 20 GHz. This sweep is completely unbroken and gap-free within its designated bands, making it highly effective for identifying narrow filter resonances or sudden impedance mismatches in real time. Synthesized signal generators, by contrast, lock to discrete frequency points using digital phase-locked loops (PLLs). While synthesizers offer exact digital control, they traditionally require finite settling times to switch frequencies, resulting in a stepped sweep rather than a single continuous wave.
Spectral Purity, Accuracy, and Level Control
The trade-off for the rapid, continuous tuning of analog sweepers lies in raw frequency accuracy and phase noise close to the carrier. The Keysight Technologies (Agilent HP) 83592A features CW frequency accuracy ranging from ±10 MHz in Band 1 (0.01 to 2.4 GHz) up to ±25 MHz in Band 4 (13.5 to 20.0 GHz). Synthesized sources achieve much tighter accuracy aligned to internal reference clocks. However, analog sweepers remain highly competitive for scalar measurements due to high leveled output power and excellent source matching. The 83592A provides +10 dBm maximum leveled output power with a power flatness of ±0.9 dB, maintaining a source SWR below 1.6 from 0.01 to 8 GHz and below 1.9 from 8 to 20 GHz.
Example instruments
Frequently asked questions
- What is the primary benefit of an analog sweep oscillator plug-in?
- Analog sweep oscillator plug-ins, like the 83592A, provide a truly continuous frequency sweep without step-and-dwell delays, allowing for instantaneous reflection and transmission measurements.
- How does the Keysight Technologies 83592A organize its broadband frequency range?
- It operates from 10 MHz to 20 GHz across four distinct frequency bands: Band 1 (0.01 to 2.4 GHz), Band 2 (2.4 to 7.0 GHz), Band 3 (7.0 to 13.5 GHz), and Band 4 (13.5 to 20.0 GHz).