Low-noise slew-rate free voltage preamplifier with current-limited continuous reset

A novel low-noise BiCMOS voltage preamplifier for the readout of high-resolution silicon detectors has been developed and characterized. This preamplifier features a feed-forward path in the gain stage that completely removes the slew-rate (SR) limitation without affecting the stability, the linearity or the noise performance. A transconductance amplifier biased at a very low current provides a low-noise current-limited continuous reset. The measured step response of the realized prototypes shows no SR limitation and a linearity error better than 0.1% within the tested output dynamic. Coupling this preamplifier to a silicon drift detector we measured a room temperature energy resolution of 165 eV FWHM at the 5.9 keV line.