Femto Messtechnik is now offering the transimpedance amplifier DLPCA-200 for measuring currents in the sub-pico to milli-Ampere range. It offers a maximum bandwidth of 500kHz equivalent to a rise time of minimum 700ns. The multi-stage amplifier is optimised for low input noise of minimum 4 fA/root Hz. It has a DC-coupled signal path to avoid baseline shifts and signal over /undershoots when measuring pulses and transients with long decay times. For applications where only AC signals are of interest, the device can also be AC coupled and any DC background signals will be filtered out.

An integrated offset control is useful for adjusting the baseline or subtracting offset currents. For ultra-sensitive measurements the bandwidth and related broadband noise can be further reduced by applying the internal signal filter. In addition to the manual control of all functions directly at the device, an integrated, opto-isolated digital interface allows for remote control by PC or external electronics. The amplifier comes in a very compact and rugged metal housing with special surface treatment for optimised EMI shielding. Due to its small size it can be used directly at the source before the signal gets degraded by long cables or interfering equipment.

The DLPCA-200 is suitable for the amplification and measurement of small currents generated by high-impedance sources such as photodiodes, APDs, PMTs or ionisation detectors. Typical applications include surface inspection, spectroscopy, particle detection, fast current and resistance measurements, STM and cAFM, laser physics, general lab use and as front-end for lock-in amplifiers, oscilloscopes and A/D converters.