抄録
The square root converter extracts the output signal which is proportional to the square root of the input signal. It primarily is designed for operation with orifice type flow measuring system.
It consists of a high gain amplifier and a thermal converter which is placed in the feedback circuit of the amplifier. The output e. m. f. given by the thermal converter is proportional to the square of the heater current. Actually, however, a conventional thermal converter does not completely obey this simple square-law relationship, and consequently errors may result when it is used in a square root converter.
The authors have developed thermal converters, which have excellent square-law performance, investigating the materials and dimensions of their heater and thermocouple, and set up a square root converter, which has 0.2% accuracy and fast dynamic response, using the thermal converter. This paper describes both theoretical and experimental works on the thermal converter and square root converter, especially, analysis of static error due to a finite gain of feedback loop and stabilizing method using a non-linear amplifier.
