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Ultra Low Noise Amplifier, Preamplifier

Current Amplifier

Ultra low noise amplifier series LCA
  • Ultra low noise - input noise down to .2 fA/Hz
  • Bandwidth up to 400 kHz
  • Gain up to 1013 V/A
  • Flat Frequency Response
  • EMI-Shielded Case

Why use a Preamplifier Module?
Unlike desktop-amplifiers, preamplifier modules provide gain close to the detector before the signal-to-noise ratio significantly decreases due to cable capacitance and noise pickup. Signal processing and measuring after preamplifying has no effect on the signal/noise performance.

Gain and Noise
In order to achieve an extremely low noise performance in the LCA current amplifier very high gains were chosen, while nevertheless minimizing the associated bandwidth reduction. Thus, as a result of our sophisticated development efforts, we can offer a professional "High-End" current amplifier line. The noise performance of our products surpasses by far that of conventionally designed OpAmp-current-to-voltage converters at the corresponding bandwidth.

Bandwidth and Frequency Response
FEMTO ultra low-noise current amplifiers show almost ideal behavior without the need for special adaptations or frequency compensations. Bandwidth and frequency response are independent of source capacitance up to 10nF. No gain peaking will occur.

Preamplifier for Lock-Ins
Lock-in amplifiers usually have a special current input. By using instead a low noise preamplifier in noise limited experiments, even the sensitivity and speed of a DSP Lock-in is strongly increased. Femtoampere currents can then be measured within a few milliseconds.

Photodetection with PMTs and Photodiodes
Scanning Tunneling Electron Microscope
Ionization Detectors
Pyro and Pyroelectric Detectors

Variable Gain Current Amplifier Comparison


Ultra low noise amplifier selector:

Click Part # to view pdf datasheet

Model 3-dB Bandwidth
(DC ...)
Noise Current
Transimpedance (Gain) [V/A] Rise/Fall Time


Variable - see DDPCA product page


2 Channel Variable


Variable - see DLPCA product page

2 Hz 0.2 fA 1 x 1012 and
1 x 1013 switchable
200 ms
LCA-30-1T 30 Hz 0.5 fA 1 x 1012 12 ms
LCA-30-200G 30 Hz 0.5 fA 2 x 1011 12 ms
LCA-200-100G 200 Hz 1.5 fA 1 x 1011 2 ms
LCA-200-10G 200 Hz 1.5 fA 1 x 1010 2 ms
LCA-1K-5G 1 kHz 3 fA 5 x 109 400 μs
LCA-2K-2G 2 kHz 4.5 fA 2 x 109 200 μs
LCA-4K-1G 4 kHz 6.5 fA 1 x 109 100 μs
LCA-10K-500M 10 kHz 10 fA 5 x 108 40 μs
LCA-20K-200M 20 kHz 14 fA 2 x 108 20 μs
LCA-40K-100M 40 kHz 19 fA 1 x 108 10 μs
LCA-100K-50M 100 kHz 30 fA 5 x 107 4 μs
LCA-200K-20M 200 kHz 40 fA 2 x 107 2 μs
LCA-400K-10M 400 kHz 65 fA 1 x 107 1 μs
NOTE: Bandwidth and frequency response are absolutely independent of Detector Capacitance. Guaranteed and 100 % tested up to 10 nF for each amplifier.
Low Noise Input/Output Cable available: CAB-LN1 Low Noise Cable

Output voltage + 10 V
@ 10 kOhm load. Offset adjustable by trimpot or external control voltage. AC-Coupling optional. Output short-circuit protected. Power supply via 3-pin LEMO socket. A mating connector is provided with the device. Optional power supply PS-15 is available. For further information, please view datasheets.

FEMTO Product Catalog (pdf)

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