Patent ID: 8206031
Filing Date: 2012-06-26
Classification: G01K

Abstract:
1. A pulse density modulation (PDM) output temperature sensor comprising: a first constant current source provided between a power supply terminal and a seventh node; a second constant current source provided between the power supply terminal and an eighth node; a first switch provided between the seventh node and a first node; a second switch provided between the seventh node and a fourth node; a third switch provided between the eighth node and the first node; a fourth switch provided between the eighth node and the fourth node; a first PNP bipolar transistor having a base and a collector connected to a ground terminal, and an emitter connected to the first node; a second PNP bipolar transistor having a base and a collector connected to the ground terminal, and an emitter connected to the fourth node; a fifth switch and a first capacitor provided between the first node and a second node in the stated order; an eighth switch provided between the second node and a third node; a sixth switch and a second capacitor provided between the first node and the second node in the stated order; a ninth switch and a third capacitor provided between the second node and the third node in the stated order; a seventh switch provided between the ground terminal and a connection point between the sixth switch and the second capacitor; a tenth switch and a fourth capacitor provided between the fourth node and a fifth node in the stated order; a thirteenth switch provided between the fifth node and a sixth node; an eleventh switch and a fifth capacitor provided between the fourth node and the fifth node in the stated order; a fourteenth switch and a sixth capacitor provided between the fifth node and the sixth node in the stated order; a twelfth switch provided between the ground terminal and a connection point between the eleventh switch and the fifth capacitor; an amplifier having a non-inverting input terminal connected to the second node, an inverting input terminal connected to the fifth node, a non-inverting output terminal connected to the sixth node, and an inverting output terminal connected to the third node; a comparator having a non-inverting input terminal connected to the third node, and an inverting input terminal connected to the sixth node; a latch having an input terminal connected to an output terminal of the comparator; an inverter having an input terminal connected to an output terminal of the latch, and an output terminal connected to an output terminal of the PDM output temperature sensor; and an oscillation circuit for controlling each of the first switch, the second switch, the third switch, the fourth switch, the sixth switch, the seventh switch, the eighth switch, the ninth switch, the eleventh switch, the twelfth switch, the thirteenth switch, the fourteenth switch, and the latch.