Which Keysight amplifier should I pick if I need roughly watt‑class output?

For watt‑class P1dB in a compact system amplifier, look at the 83020A family of modules, which are specified to deliver watt‑class output in their core band and are intended for system integration.

Which models are intended specifically as low‑noise preamplifiers for improving receiver sensitivity?

Low‑frequency and microwave preamplifiers are purpose‑built for sensitivity improvement. The 11909A is an example at lower frequencies (kHz to 1 GHz) and units such as the 8449B are positioned as microwave preamplifiers for analyzer/EMI receiver front ends.

What interface and power considerations should I check before integrating an amplifier?

Confirm RF connector type and power/bias method. Some amplifiers use DC bias interfaces (cables or D‑sub), bench units use mains, distribution amps use BNCs, and certain modules require host mainframe power. Match the amplifier's connector and supply method to your system before integration.

Keysight Technologies (Agilent HP) Amplifiers

11 models with full specifications in Amplifiers.

This page summarizes Keysight (formerly Agilent/HP) amplifiers across low‑frequency preamplifiers, broadband system amplifiers, bench microwave amplifiers and specialized receiver/distribution modules. It is written for engineers and technical buyers choosing an amplifier for measurement front ends, system integration, signal conditioning, or RF distribution. The copy explains how the product set is organized, the technical tradeoffs to weigh (frequency, gain, output power, noise, connectors and power), and which product types are appropriate for common tasks such as increasing receiver sensitivity, recovering system loss, or driving downstream millimeter‑wave modules.

Widest frequency span: 83050A: 2 to 50 GHz
Highest minimum P1dB (system amp): 83020A: +30 dBm (2.0–20.0 GHz, minimum)
Lowest frequency limit: 11909A: 9 kHz to 1 GHz
Minimum small-signal gain (ultra-broadband preamp): 83051A: 23 dB (minimum)
Common RF connectors: 3.5 mm (8449B); 2.4 mm (83051A); Type-N (8347A)

All models

Model	Type	Power Supply	Dimensions (W×H×D)	Operating Temperature
8449B	Preamplifiers	—	—	—
83050A	Microwave	+12 VDC @ 1.3 A, -12 VDC @ 20 mA (via Keysight 87421A or compatible power supply)	45 mm × 45 mm × 114 mm	0 to 55
8349B	Microwave	100 / 120 / 220 / 240 VAC (+5%, -10%), 48 to 66 Hz, 85 VA maximum	214 mm × 133 mm × 366 mm	0 to 55 °C
8447D	Preamplifiers	100 / 120 / 220 / 240 V AC (±10%), 48 - 440 Hz, 15 VA	216 mm × 130 mm × 285 mm	0 to 55 °C
5087A	Distribution	115 / 230 V AC ±10% (48 to 440 Hz), 20 VA max; 22 to 30 V DC, 300 mA max	425 mm × 88.9 mm × 286 mm	0 to 50 °C
11909A	*misc	100 / 120 / 220 / 240 V AC (+10%, -15%), 47 to 66 Hz	110 mm × 117 mm × 216 mm	0 to 55 °C
83020A	Microwave	+15 VDC @ 3.2 A (max), -15 VDC @ 50 mA (max); compatible with Keysight 87422A 70W power supply	103 mm × 45 mm × 182 mm	0 to +55 °C
83051A	Microwave	+12 VDC @ 330 mA, -12 VDC @ 30 mA nominal (requires external supply, fully compatible with Keysight 87421A)	103 mm × 45 mm × 167 mm	0 to +55 °C
8347A	RF	100 / 120 / 220 / 240 VAC (±10%), 48 - 66 Hz	213 mm × 102 mm × 297 mm	0 to 55 °C
83486A	*misc	Powered directly from host DCA mainframe backplane	—	—
87405A	Preamplifiers	+15 VDC @ 80 mA (via probe-power cable)	45 mm × 22 mm × 115 mm	0 to 55 °C

How the Keysight amplifier range is organized

Keysight's amplifier offering in this category breaks down into a few practical groups: low‑frequency low‑noise preamplifiers for sensitivity improvement; ultra‑broadband system preamplifiers and power boosters for system designers and integrators; general‑purpose bench and microwave amplifiers for lab use; and specialized modules for distribution or optical/electrical reception.

Examples that illustrate the groups: the 11909A is a low‑frequency low‑noise amplifier covering down to single‑digit kHz; the 83051A and 83020A are ultra‑broadband system amplifiers for integrators; the 8349B and 8347A are bench microwave amplifiers spanning multi‑GHz bands; the 5087A is a frequency distribution amplifier for reference signals; and the 83486A is an optical/electrical receiver plug‑in for DCA mainframes.

Key technical differentiators

Frequency coverage is the primary divider: models span from 9 kHz (11909A) up to 50 GHz (83050A). Gain and gain flatness vary by intended role — preamplifiers prioritize high small‑signal gain with tight flatness for low‑level measurements (for example, the 11909A specifies nominal 32 dB gain with ±0.5 dB flatness across most of its band), while system amplifiers trade some flatness for very wide bandwidth and higher output power.

Output power capability and compression behavior separate system/power amplifiers from preamps. System amps such as the 83020A are specified with watt‑class output at 1 dB compression over their primary band; other system or microwave amps (for example, 83050A and 8349B) specify multi‑decibel P1dB and saturated output values appropriate for driving downstream components. Noise figure and third‑order intercept (IP3/OIP3) are the relevant linearity and sensitivity metrics — models intended to improve analyzer sensitivity emphasize low noise and high gain, while driver amps prioritize P1dB/OIP3 and leveled output.

How to choose between models

Select by the three primary constraints of your application:

Frequency band required. Match the amplifier whose guaranteed band fully contains your operating band (for example, pick a 2–50 GHz unit when signals extend into the upper millimeter‑wave range).
Required output drive and linearity. If you need to recover system losses or drive power-hungry modules, choose a system/power amplifier with specified P1dB and saturated output; if you only need to improve receiver sensitivity, a preamplifier with higher small‑signal gain and lower noise is appropriate.
Sensitivity and dynamic range. For the highest sensitivity at low frequencies choose a product optimized for low noise and tight gain flatness; for wideband systems prioritize the amplifier's flatness and gain over the full band.

Other selection items: check connector types and available power/bias options (for example, some system modules use DC bias cables or D‑sub power interfaces, while rack/bench amplifiers use mains power).

Practical installation and interface notes

Pay attention to RF connectors, power/bias requirements, and mechanical footprint when integrating an amplifier into a test rack or system. Examples: the 8449B uses 3.5 mm female RF connectors; the 83051A uses a 2.4 mm female RF input; the general bench amplifier 8347A uses Type‑N input; and system modules such as the 83020A present a 15‑pin D‑sub bias/power interface and require a compatible supply. The 5087A uses BNC connectors for frequency distribution applications, and the 83486A is a plug‑in module that interfaces to a DCA mainframe and includes optical connector adapters.