PURPOSE: To obtain a signal processing circuit suitable for large scale integration by employing such circuitry as a flying capacitor capacitor functions as a differential amplifier and a sample & hold circuit thereby decreasing the overall chip area.
CONSTITUTION: The input switches for flying capacitors 21, 22 are normally turned ON while being interlocked with the lighting of a light source 1. Current/ voltage converters I/V1-I/V4 then convert the output currents from photoelectric converting elements H1-H4 into voltages and the capacitors 21, 22 operationally hold the difference of output voltages as ON data. A multiplexer 8 alternately selects and converts 9 the output signal to produce a digital signal which is subjected to various operations thus determining a phase θ. At the time of offset correction, the capacitors 21, 22 are turned ON under unlighted state to operationally hold the difference of output voltage as OFF data which is then fed to the multiplexer 8. Offset correcting operation 10 is effected based on the ON and OFF data. This constitution provides the flying capacitor with the function of subtractor and sample & hold circuit.
KOSAKA FUSAO
NAKAYAMA HIROSHI
