Alternative circuit topologies for charge preamplifiers and pulse shapers

The circuits presented in this work are developed with motivation to improve dynamic performance of charge preamplifiers and pulse shapers used with solid state radiation detectors. Specifically, dynamic performance of a charge preamplifier is improved by introducing an active filter in its gain loop. In addition, benefits of a charge preamplifier that uses separate feedback loops for the capacitor and resistor are also discussed. Further, it is demonstrated that an active band-pass filter can be used for pulse shaping, instead of the conventional topology comprising a pole-zero compensation circuit and a low-pass filter. Finally, it is shown that a circuit with nested feedback loops has certain advantages as an alternative to the conventional charge preamplifier and pulse shaper combination. Under the same operating conditions, it is harder to drive this circuit into saturation than a typical charge preamplifier, which makes it more suitable for applications with high incident photon rates, where it also improves discrimination between successive photons. All circuits are purely analogue, which eliminates the need for additional protective measures which are unavoidable in the mixed mode circuits. The circuits are designed for implementations in the forms of discrete electronics modules or hybrids, however, the same concepts can also be used for implementations in ASICs.