As part of the German FEMTO HCA fixed-gain current amplifier series, the HCA-400M-5K-C current preamplifier is designed for high-speed signal processing with exceptional dynamic response capabilities. Its core specifications include: 400 MHz (-3dB) flat bandwidth, 5×103 V/A fixed transimpedance gain, and 1 ns ultra-short rise/fall time, enabling precise capture of nanosecond-level transient signals. The device employs an optimized transimpedance architecture design, ensuring 400 MHz bandwidth while suppressing input current noise to 20 pA/√Hz (typical value), significantly enhancing weak signal detection sensitivity.

Product Features:

Bandwidth DC…400 MHz

Rise/Fall Time 1ns

Optimized for low pulse distortion—minimal overshoot or ringing

Transimpedance (Gain) 5 x 103 V/A

Product Applications:

Photodiode and photomultiplier amplification

Spectroscopy

Ionization detectors

Ideal for analyzing digital signals (no baseline shift for any digital code)

Preamplifier for A/D converters, digitizers, etc.

Key Technical Advantages:
Source Capacitance Independence Design: Breaks through the bottleneck of traditional current amplifier bandwidth limitations caused by source capacitance. Even with detector capacitance up to 10 pF, it maintains nominal bandwidth and gain stability without additional frequency compensation.

Dual Precision Adjustment System: Enables ±1.5 V output offset calibration via independent fine-tuning potentiometers and supports continuously adjustable photodiode bias voltage from -12 V to +12 V, optimizing detector response speed.

High-Frequency Stability Enhancement: Utilizes EMI shielded housing and low-noise amplification circuitry to effectively suppress self-oscillation and gain peaking, ensuring ±1 dB flatness within the 400 MHz frequency band, suitable for precise measurement of high-frequency signals.

Typical Application Scenarios:

Ultrafast Photodetection: Matches nanosecond-response photodiodes for applications such as laser pulse detection and time-correlated single photon counting (TCSPC).

Spectroscopic Analysis Systems: Achieves high-fidelity amplification of weak photocurrent signals in broadband spectrometers, supporting femtosecond laser spectroscopy research.

Particle Detection Technology: Used in conjunction with PMTs (photomultiplier tubes) or ionization chambers to process transient current signals in nuclear physics experiments.

Material Characterization: Applied in ultrafast photoconductivity measurements, exciton dynamics studies, and other condensed matter physics experiments.

This model comes standard with 50 Ω load-matched output, selectable AC/DC coupling, and short-circuit protection. It is powered via a 3-pin Lemo connector and is compatible with the PS-15 dedicated power module. The FEMTO HCA-400M-5K-C undergoes rigorous testing at the German factory and is suitable for research laboratories, industrial inspection, and high-end instrument integration, providing a reliable solution for high-frequency weak current signal processing.

Model: HCA-400M-5K-C

Bandwidth: 400 MHz

Current Noise:   20 pA

Variable Gain: 5 x 103 V/A

Rise/Fall Time:   1 ns

Maximum Source Capacitance: 10 pF