Power detector device and power detection method

A power detection method, comprising:

• generating a bias voltage and a detection voltage according to a power supply voltage;
• generating a first reference voltage according to the power supply voltage;
• turning on a switch to transmit the first reference voltage to a node when the bias voltage is sufficient to turn on the switch, and turning off the switch to stop transmitting the first reference voltage to the node when the bias voltage is insufficient to turn on the switch;
• charging a capacitor by the first reference voltage to generate a second reference voltage, the capacitor being coupled between the node and ground, and holding a level of the second reference voltage by the capacitor after the switch is turned off;
• outputting the second reference voltage via the node;
• and
• comparing the second reference voltage with the detection voltage to generate a power detection signal.

A power detector device, comprising:

• a voltage generator circuit, generating a bias voltage and a detection voltage according to a power supply voltage;
• a reference circuit, generating a first reference voltage according to the power supply voltage;
• a level hold circuit, transmitting the first reference voltage to a node when the bias voltage is sufficient to cause the transmitting, outputting a second reference voltage via the node, and holding a level of the second reference voltage after the bias voltage becomes insufficient to cause the transmitting such that the transmitting of the first reference voltage to the node is stopped;
• a comparator circuit, comparing the second reference voltage with the detection voltage to generate a power detection signal;
• and
• a delay circuit, generating an enable signal after a delay period that is timed from power-on of the power supply voltage using a clock signal,
• wherein the comparator circuit is activated according to the enable signal to start comparing the second reference voltage with the detection voltage after the delay period elapses.