Methods of Reducing Noise of Junction Field Effect Transistor (JFET) Amplifiers

At present in non-dispersive X-ray spectrometers the electronic noise of the pulse amplifier input circuit prevents full realization of the inherent resolution of the semiconductor detector. Commercially available low noise JFET's encapsulated with boro-silicate (7052)glass insulated headers have typical noise contributions to detector resolution widths (FWHM), at 25°C, of 326 eV (Si). JFET's encapsulated with BeO or Al2O3 headers contribute ~200 eV to the resolution at 25°C and 150 eV at about -20°C. Techniques to select passive components which do not inhibit the performance of these transistors are discussed.