Patent ID: 8604837
Filing Date: 2013-12-10
Classification: G01R

Abstract:
1. A detector circuit, comprising: a first diode, to an anode of which an AC signal is input and to which a constant voltage is supplied; a second diode, to an anode of which the constant voltage is supplied; and a difference current generation circuit, which generates a difference current between a first current flowing in the first diode and a second current flowing in the second diode, wherein the difference current generation circuit comprises: a first current mirror circuit which is provided on a cathode side of the first diode, and which generates a third current having a current value which is a product of the first current and a first current mirror ratio; a second current mirror circuit which is provided on a cathode side of the second diode, and which generates a fourth current having a current value which is a product of the second current and a second current mirror ratio; a third current mirror circuit, which generates either a fifth current having a current value which is a product of the third current and a third current mirror ratio, or a sixth current having a current value which is a product of the fourth current and the third current mirror ratio; a coupling node at which are coupled a path of the fifth current and a path of the fourth current, or a coupling node at which are coupled a path of the sixth current and a path of the third current, the difference current being generated at the coupling node; and a calibration circuit, which in a state in which input of the AC signal is intercepted, variably sets at least one of the first, second and third current mirror ratios such that the difference current is reduced.