Abstract: A circuit according to the present invention includes: an oscillator; an divider; a time-to-digital converter comparing the phase and frequency of a reference clock signal REF from the divider with an internal clock signal and outputting digital data D1 based on the comparison results; a digital loop filter receiving the D1 and outputting digital data W1; a data holder holding the W1 from the filter in time series manner; a switch selecting either digital data W2 from the holder or the W1 and outputting the selected data as digital data W3; a digitally controlled oscillator with oscillation frequency controlled based on the W3; and a data controller switching input data of the switch, and starting/halting the operation of the oscillator, the divider, the converter and the filter. Current consumption by the digital PLL circuit can be reduced.

Abstract: There are provided a current sensor which has a self-diagnosis function and a signal processing circuit. The current sensor is provided with an offset component output circuit 102 which extracts an offset component from an output signal of a Hall element 101 which includes a signal component and an offset component, a reference signal generator 103 which outputs a reference signal, and an error signal generation circuit 104 which generates an error signal based on an offset component which the offset component output circuit 102 outputs and a reference signal. The offset component output circuit 102 is provided with a signal amplification circuit 106 which amplifies the output of the Hall element 101 and outputs an output signal and offset component to a low frequency component and the other to a ripple component.

Abstract: A physical quantity measuring apparatus of the present invention measures a physical quantity from a signal based on a physical quantity output by a physical quantity signal output apparatus. A correction signal output unit outputs a new correction signal based on a signal on the basis of a physical quantity obtained at a given measurement time, a correction signal obtained before that measurement time, and a filter coefficient. A large/small relationship determining unit determines a large/small relationship between the signal on the basis of the physical quantity and the correction signal obtained before that measurement time. A first filter coefficient output unit outputs a first filter coefficient based on the plural large/small relationships.

Abstract: A Hall electromotive force signal detection circuit combines offset cancellation means by a spinning current method of a Hall element with a continuous-time signal processing circuit. A first Hall element includes first to fourth terminals, and generates a Hall electromotive force signal voltage Vhall1. A third Hall element generates an other Hall electromotive force signal voltage Vhall3. A first switching circuit selects a terminal position for applying a drive current from the four terminals of the first Hall element. A third switching circuit selects a terminal position for applying a drive current from the four terminals of the third Hall element, which is different from the terminal position selected by the first switching circuit. A chopper clock generation circuit supplies a chopper clock signal ?1, ?2 having two different phases to the switching circuit, and also supplies the chopper clock signal ?1, ?2 to the switching circuit.