摘要:
This invention relates to a method and apparatus for simulating a surface photo-voltage, more particularly with a photodiode on a process sized disk for calibrating surface photo-voltage measurement devices. The device for simulating a surface photo-voltage includes the photodiode, the disk, a resistor, and may further include an operational amplifier. The apparatus for simulating a surface photo-voltage of the current invention facilitates calibration of surface photo-voltage measurement devices by using a process sized disk to fit directly on a surface photo-voltage measurement chuck.
摘要:
An autozero compensation system for autozeroing the output of a data conversion circuit comprising a floating point amplifier and an analog-to-digital converter. The autozero compensation system comprises a source for generating a desired offset voltage, a plurality of digital counters, one for each gain setting of the amplifier, for storing values which are functions of the offset voltages for the gain settings, and a comparator for comparing the output of the A/D converter with the desired offset. Periodically, each of the counters in the autozero circuit is updated for each gain setting by setting the analog input of the amplifier to system ground and the gain of the amplifier set to each of the gain settings, so that the output of the comparator is used to update each of the counters. The outputs of the counters are each converted to analog form by a D/A converter and used to provide the offset correction voltage to the floating point amplifier.