The Keysight N4985A is a high-performance broadband RF amplifier delivering exceptional gain and output power across baseband to millimeter-wave frequencies. Engineered for demanding test environments, R&D, and production applications, the N4985A combines a self-contained design with standard AC power supply operation and compact form factor. Proximity mounting to devices under test minimizes signal path losses and maximizes output power delivery where needed most.
Technical Specifications
Frequency Coverage:
The N4985A series spans four variants addressing specific frequency requirements:
• N4985A-P15: 10 MHz to 50 GHz
• N4985A-P25: 2 GHz to 50 GHz
• N4985A-S30: 100 kHz to 30 GHz
• N4985A-S50: 100 kHz to 50 GHz
Gain:
Up to 30 dB gain to 26 GHz (N4985A-S30). The N4985A-P25 delivers 27 dB gain with +2 dB flatness at 20 GHz.
Output Power:
Saturation power reaches 1 W (30 dBm) Psat to 10 GHz on applicable models. At 20 GHz: 26 dBm P-1dB and 29 dBm Psat. At 50 GHz: typically 22 dBm output power. The N4985A-S30 provides 22 dBm Psat at 26 GHz.
Noise Figure:
Less than 5 dB noise figure on the N4985A-S30 across specified ranges.
Return Loss (S22):
Typical values range from -6 dB to -15 dB across frequency bands.
Reverse Isolation (S12):
Typically -60 dB in certain bands, -50 dB in others.
Harmonic Suppression:
2nd harmonic at P-1dB: typically -40 dBc to -3.5 dBc depending on frequency band.
3rd harmonic at P-1dB: typically -20 dBc to -30 dBc.
Power Supply:
Standard AC input. DC specifications: 9 V at 1.5 A (N4985A-P25).
– Key Features
• Compact form factors: N4985A-P25 measures 5.5 x 4.5 x 2.75 inches; N4985A-S30 measures 3.5 x 3.5 x 1 inch
• Built-in cooling fan for thermal management
• 2.4 mm female connectors (input/output) on select models; Type N-Female on others
• Self-contained module design
– Typical Applications
Broadband amplification for RF test fixtures, millimeter-wave measurement systems, component characterization, and production line verification across DC-to-50 GHz bands.
– Compatibility & Integration
Optional N4985A-OA3 optical applique available for extended system integration.
