PURPOSE:To measure radiant rays effectively by setting a voltage in switching lower than the circuit voltage when a signal pulse is at 0V, in an AD converter suitable for the radiant-ray measurement CONSTITUTION:An input signal is led to linear gate 12 via input buffer 11 and the output of the gate is further inputted to synchronizer 19 by way of stretcher 13, peak detector 14 and clock gate 15 The other output of stretcher 13 is led via high speed/low speed change-over switch level detector 18 to synchronizer 19, whose outputs are supplied to channel scaler 20 to adjust the gain via conversion gain switch 21 Then, a digital value equivalent to an offset voltage is subtracted out of scaler 20 Thus, invariably excellent linearity is obtained without reference to the level of the voltage of the signal pulse, and the radiant-ray measurement is carried out effectively

Method of improving differential linearity of ad converter

PURPOSE:To obtain a converting output with excellent differentiation nonlinearity by subtracting a signal corresponding to a reference level from a measured analog input signal in advance when the input signal exceeds a value converted as it is by an A-D converter and adding them after the conversion to apply uniforming processing using a pedestal signal. CONSTITUTION:When the measured analog input signal 12 passing through the analog arithmetic unit 13 is inputted to the A-D converter 14 as it is, an overflow signal 27 is outputted. An output signal of an A-D converter 19, that is, the analog pedestal signal 23 becomes an analog value corresponding to the digital pedestal signal 22 added with the overflow component. The value obtained in this way is subtracted from the measured analog input signal 12 and the result is inputted to the A-D converter 14. Thus, the A-D converter converts even a measured analog input signal exceeding the maximum converting value of the A-D converter by subtracting the analog pedestal signal corresponding to the maximum converting value from the measured analog input signal at the pre-stage of digital conversion.

Nakamura Kimihiko

Papers

Method of improving differential linearity of ad converter

Analog-digital converter