Electrical noise thermometer

Abstract

A resistance in thermal equilibrium develops a noise voltage intensity which is directly proportional to the absolute temperature and is given by the well-established formula$\overline {v_n^2 } = 4R kT\Delta f$. A novel circuit is described which uses a quasi-null technique to make the measurement less sensitive to many of the amplifier properties such as gain and bandwidth. The performance of a prototype circuit is given.