Transimpedance Amplifiers for Life and Material Science

Many life and material science applications like Scanning Ion Conductance Microscopy (SICM) and Electrically Detected Magnetic Resonance put demanding constraints on readout electronics. In a SICM experiment a pipette is used to map the surface of soft biological samples. An EDMR experiment is used to derive the efficency of solar cell materials.

Both applications have in common that they convert there information of interest into a current signal which can then be processed with a transimpedance amplifier. Since the present current signals are in the pico ampere range a low noise transimpedance amplifier with a noise floor in the lower femto ampere range is required. To resolve especially dynamic effects in the exeriments a transimpedance amplifier is needed with a bandwidth in the MHz range.

Only continous-time transimpedance amplifiers are capable of combining both fast and low noise current detection. Therefore the topolgy of choice is the implementation of Ferrari et al. [1]. This circuit implementation is changed for the needs of the above named application. The focus lies especially on the Pseudo-Resistor which is replaced by a novel Multi-Element Pseudo-Resistor of Djekic et al. [2] which reduces the shot noise at the present of non-zero DC currents.

[1] G. Ferrari et al., "Transimpedance amplifier for high sensitivity current measurements on nanodevices" IEEE Journal of Solid-State Circuits.
[2] D. Djekic et al., "A transimpedance amplifier using a widely tunable pvt-independent pseudo-resistor for high-performance current sensing applications" in ESSCIRC 2017.  

Project member

M.Sc. M. Häberle