On the Use of Supercapacitors for DC Blocking in Transformer-Coupled Voltage Amplifiers for Low-Frequency Noise Measurements

When performing low-frequency noise measurements on low-impedance electron devices, transformer coupling can be quite effective in reducing the contribution of equivalent input voltage preamplifier to background system. However, devices are usually performed with a biased device under test. A bridge configuration must used null DC component at transformer. Unfortunately, using results complication set-up and degradation system’s sensitivity because introduced by nulling arm. We propose an alternative approach for blocking that exploits fact supercapacitors capacitances excess few Farads nowadays easily available. Actual measurement conventional advanced configurations discussed demonstrate advantages we propose.