Keysight (Agilent) 1131A InfiniiMax 3.5 GHz Probe

The Keysight 1131A InfiniiMax is a 3.5 GHz active probe designed for high-speed differential and single-ended signal measurements on embedded designs. This probe minimizes loading effects on the Device Under Test through extremely low input capacitance, flat frequency response, and resistor probe tip technology, delivering superior signal fidelity for accurate waveform capture. The system integrates with Infiniium oscilloscopes via the AutoProbe Interface and supports a comprehensive ecosystem of probe heads and connectivity accessories to meet diverse mechanical access requirements.

Technical Specifications

• Bandwidth: 3.5 GHz


• Dynamic Range: ±2.5 V


• DC Offset Range: ±12 V


• Maximum Input Voltage: ±30 V


• Input Impedance (Differential): 50 kΩ with 0.27–0.34 pF capacitance


• Input Impedance (Single-Ended): 25 kΩ with 0.44–0.67 pF capacitance

Key Features

• Extremely low input capacitance minimizes DUT loading and preserves signal integrity


• Flat frequency response across the 3.5 GHz bandwidth ensures accurate representation of test signals


• S2 resistor technology with optimized 91 Ω values (legacy 100 Ω variants remain specification-compliant)


• Dual-mode operation supports both differential and single-ended probing configurations


• Broad dynamic range of ±2.5 V with DC offset capability to ±12 V accommodates varied signal levels

Typical Applications High-speed digital design validation, embedded system debugging, signal integrity analysis, and differential pair measurements in designs requiring minimal measurement artifacts.

Compatibility & Integration The 1131A operates with Infiniium 80000 and 90000 series oscilloscopes, as well as the 54853A model. Required connectivity kits include the E2669A (differential/single-ended) and E2668A (single-ended). Compatible probe heads span differential (E2675A, E2677B, E2678B) and single-ended (E2679A) options. The system integrates with the N1022A probe adaptor for use with the Infiniium 86100A Digital Communication Analyzer and operates with the external 1143A power supply. Accessory options include the N2880A in-line attenuator and N2881A DC blocking capacitors.