Abstract: A comparator device is designed for comparing the signal levels of first and second input signals to provide respective of resultant comparator outputs independently, which comparator device is featured in avoidance of occurrence of simultaneous low levels of the comparator signals at all possible conditions of the comparator outputs. The comparator device includes first and second comparator which independently output resultant comparator outputs either of H level and L level as results of comparison of the signal levels of the first and second input signals with taking one of the input signals as reference, and have offset characteristics and hysteresis characteristics so that the comparator outputs, either H level or L level can be fixedly determined when the first and second input signal levels are equal to each other.

Abstract: An amplifier is operated with a low power source voltage and has a reference voltage of 1.25 V or less. The temperature characteristic of the amplifier is controllable. The amplifier comprises substantially similar circuits and constants on its left and right sides under a condition that a voltage source is not connected to an input terminal, except that a diode-connected transistor is provided. Paying attention to the left-side circuit, the circuit which has the diode-coupled transistor having a forward voltage and resistors 22 and 23, is expressed by an equivalent circuit by the (Ho)-Thevenin theorem.

Abstract: A fault in a logic IC device including a plurality of logic cells is diagnosed by the use of an intentional fault. The intentional fault is introduced into a portion of logical operation data for the logic cells of the device to produce a faulty logical operation data. That portion of the logical operation data corresponds to a fault candidate which represents a location in the device at which hazard is supposed to have occurred to make it uncertain whether or not a fault exists at the location.

Abstract: An angle modulation detector which prevents a demodulated output from being influenced by fluctuations in the amplitudes of signals generated from angle-modulated signal sources such as a phase-modulated signal and a frequency-modulated signal, even if the amplitude of a driving voltage applied to a connection between the bases of a pair of transistors constituting a phase detecting device is made larger in order to enhance the demodulation sensitivity and reduce noise produced during demodulation.