Cooled preamplifiers with N- or P-silicon JFET's

Abstract

A voltage sensitive cooled preamplifier has been operated with comparable resolution from n- and p-Si junction field effect transistor's (JFET's). To obtain optimum JFET operating conditions it is necessary to consider in detail the inter-related parameters of device thermal resistance, the variation of JFET noise with temperature and of gate current with drain voltage. Measurement and optimisation procedures are described.