Patent ID: 8970255
Filing Date: 2015-03-03
Classification: G01R,H03K

Abstract:
1. A frequency detection apparatus, comprising: a constant current generator, arranged for providing a constant current to a voltage output terminal; a first capacitor, coupled between the voltage output terminal and a first reference voltage; a first transistor, having a first connection terminal, a control terminal, and a second connection terminal, wherein the first connection terminal of the first transistor is coupled to the voltage output terminal, and the control terminal of the first transistor is coupled to an input signal; a second capacitor, coupled between the second connection terminal of the first transistor and the first reference voltage; and a second transistor, having a first connection terminal, a control terminal, and a second connection terminal, wherein the first connection terminal of the second transistor is coupled to the second connection terminal of the first transistor, the second connection terminal of the second transistor is coupled to the first reference voltage, and the control terminal of the second transistor is coupled to an inverted input signal; wherein a voltage output of the voltage output terminal changes along with an input signal frequency of the input signal, and the constant current generator comprises: