These high gain (10E13V/A) current integrate producing an output voltage proportional to the charge collected at the amplifier input over a certain amount of time. Often a charge amplifier needs a reset mechanism to avoid an overload of the integration stage. Designed for AC modulated signal sources with no average DC background current, the charge in these applications is alternating positive and negative and therefore no separate reset is required because the average current is zero. With extremely low input noise (40 x 10-21C/√Hz and 700pV/√Hz) these modules are ideal for AC coupled charge sources like pyroelectric and piezoelectric detectors, tuning fork quartz crystals and length extension resonators.