High Speed Transimpedance Amplifiers (Current Amplifiers) HCA


  • Input noise down to 270 fA/√Hz
  • Bandwidth up to 400 MHz
  • Transimpedance amplifiers with gain up to 106 V/A
  • Flat frequency response
  • Stabilized and adjustable bias voltage output for biasing external photodiodes
  • EMI-shielded case
Model-3 dB Bandwidth
(DC …)
Noise CurrentTransimpedance
Rise /
Fall Time
Source Capacitance
HCA-1M-1M1 MHz270 fA/√Hz1 x 106 V/A350 ns50 pF Download
HCA-1M-1M-C1 MHz3.5 pA/√Hz1 x 106 V/A350 ns2 nF Download
HCA-2M-1M2 MHz340 fA/√Hz1 x 106 V/A180 ns25 pF Download
HCA-2M-1M-C2 MHz3.5 pA/√Hz1 x 106 V/A180 ns1 nF Download
HCA-4M-500K4 MHz490 fA/√Hz5 x 105 V/A90 ns15 pF Download
HCA-4M-500K-C4 MHz3.5 pA/√Hz5 x 105 V/A90 ns500 pF Download
HCA-10M-100K10 MHz1.1 pA/√Hz1 x 105 V/A35 ns15 pF Download
HCA-10M-100K-C10 MHz3.5 pA/√Hz1 x 105 V/A35 ns150 pF Download
HCA-20M-100K-C20 MHz3.5 pA/√Hz1 x 105 V/A18 ns50 pF Download
HCA-40M-100K-C40 MHz3.7 pA/√Hz1 x 105 V/A10 ns30 pF Download
HCA-100M-50K-C100 MHz3.8 pA/√Hz5 x 104 V/A3.5 ns20 pF* Download
HCA-200M-20K-C200 MHz4.9 pA/√Hz2 x 104 V/A1.9 ns8 pF* Download
HCA-400M-5K-C400 MHz21 pA/√Hz5 x 103 V/A1 ns10 pF* Download
Output voltage ±1.5 V, @ 50 Ω load. Offset adjustable by trimpot. Output short-circuit protected. Adjustable bias-output (-12 V … +12 V) for biasing photodetectors. Power supply via 3-pin Lemo® socket. A mating connector is provided with the device. Optional power supply PS-15 available. For further information please view the datasheet. NOTE: The maximum detector capacitance listed above means that up to this value the specified 3dB-bandwidth (±15 %) is guaranteed. Larger capacitances are also possible, but will slightly influence the bandwidth and frequency response. * For the ultra fast models HCA-100M-50K-C, HCA-200M-20K-C and HCA-400M-5K-C a reduction in bandwidth up to 25 % of the nominal values might occur if the source capacitance reaches the above noted maximum source capacitance values. Especially for these models short cables at the input and the use of low capacitance sources is of major importance. For further information please view the datasheet or contact FEMTO.

High frequency – only for specialists?

Users of high frequency components are often confronted with problems including unwanted oscillation, poor ground shielding, nonlinearities, gain peaking and bandwidth reduction caused by poorly designed amplifiers. FEMTO High Frequency Amplifiers have been designed to eliminate such unwanted problems. Insensitive to signal source parameters and input wiring, FEMTO High Frequency Amplifiers perform meticulously within their specifications. No gain peaking, oscillation or significant bandwidth reduction will occur, even for source capacitances up to maximum 2 nF (for the HCA-1M-1M-C).

Bandwidth independent of source capacitance

Merely a few picofarads of source capacitance can drastically decrease the bandwidth of high frequency current amplifiers. However, FEMTO Current Amplifiers do not have this limitation and are not influenced by a wide range of source capacitances. No frequency compensation or special adaptation is needed and the bandwidth and gain are constant up to the maximum source capacitance specified for each model.


Amplifier models shown with an additional C are optimized for handling very large source capacitances up to nanofarads. They are very useful for measuring fast signals down to nanoseconds with large area detectors.

Transimpedance amplifiers with adjustable offset and bias voltage

For a high degree of flexibility FEMTO’s HCA transimpedance amplifiers offer precise offset and bias control by two trimpots. The wide range of the adjustable input offset current compensation preserves full dynamics even for signals with large DC-components. The voltage at the bias-output can be adjusted precisely from -12 to +12 Volts using the multi turn bias-trimpot.


  • Current to voltage converter for current measurement
  • Fast detection with large area photodiodes
  • Spectroscopy
  • Photodetection with PMTs and photodiodes
  • Ionization detectors
  • Pyro- and piezoelectric detectors

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Power Supply