Agilent/Keysight N4421A

The Agilent/Keysight N4421A is an S-parameter test set engineered for physical layer and balanced-measurement applications. It characterizes high-speed digital interconnects and balanced or balanced-to-single-ended RF components across 45 MHz to 50 GHz. The test set operates as a core subsystem within Keysight measurement platforms, delivering full four-port vector error correction and support for conventional single-ended and mixed-mode S-parameter analysis.

Data re-normalization for non-50-ohm devices enables accurate characterization of custom impedance systems. Fast multiple-term calibration algorithms perform true multi-port vector error correction, while integrated electronic calibration (ECal) functionality streamlines measurement setup. Time-domain analysis and user-defined parameter displays provide design insight across physical layer validation and balanced component testing workflows.

Technical Specifications

• Frequency Range: 45 MHz to 50 GHz


• Vector Error Correction: Full four-port


• Calibration: Multiple-term algorithm; four-port electronic calibration (ECal) module integration supported


• S-Parameter Display: Conventional (single-ended) and mixed-mode formats


• Data Re-normalization: Supported for non-50-ohm devices


• Analysis Options: Time-domain analysis available

Key Features

• Four-port vector error correction for high measurement accuracy


• Fast automatic calibration with ECal module integration


• Mixed-mode S-parameter measurement capability for balanced topologies


• User-defined parameter displays for custom calculations


• Time-domain analysis option for transient characterization

Typical Applications

• High-speed digital interconnect characterization


• Fully balanced RF component measurement


• Balanced-to-single-ended RF device testing


• Physical layer validation and compliance

Compatibility & Integration Works with Keysight PNA Series E8364B Option 014 and compatible Agilent PNA/PNA-L analyzers with Option 550 for four-port measurements. Requires N4425A Balanced Measurement System software or N1930A Physical Layer Test System software for operation. External PC with IEEE-488 GPIB interface required for system integration.