Design of an isolation amplifier using for plasma diagnostics

An isolation amplifier using for probe measurements in a time varying plasma is designed and constructed. The isolator is required the operation in quick frequency response and small nonlinearity error. In order to satisfy the requirements, the optically coupled isolator with high speed and linearity advantage is used. Gain nonlinearity error is supressed by means of inverse feedback in which a pair of opto isolators with same characteristics is applied. The specifications are as follows, frequency band: dc -- 0.25 MHz, gain: unity, nonlinearity: less than a percent of peak to peak output voltage span. (author)