Taiwan Semiconductor Manufacturing Comp. Ltd.

Global Unichip Corporation

Chun-Chi Chang

Chia-Hsiang Chang

Jun-Chen Chen

A power-on-detection (POD) circuit includes a detection circuit, first and second comparison circuits, and logic circuitry. The detection circuit includes a capacitor configured to charge from a first voltage level to a second voltage level. The first comparison circuit is configured to compare a third voltage level to a reference voltage level, and the second comparison circuit is configured to compare a fourth voltage level to the reference voltage level. The third and fourth levels are based on the second voltage level. The logic circuitry is coupled to an output of the first comparison circuit and to an output of the second comparison circuit and is configured to output a power identification signal based on the outputs of the first and second comparison circuits. The detection circuit is configured to turn on the first and second comparison circuits based on a voltage level of the capacitor.

Power on detection circuit

A duty cycle corrector includes an SR latch, a first switch and a second switch. The SR latch is configured to generate first and second control signals according to first and second clocks. The first switch is coupled between a work voltage and an output node, and selectively closes and opens according to the first control signal. The second switch is coupled between the output node and a ground voltage, and selectively closes and opens according to the second control signal. The output node is used to output an output clock.

Duty cycle corrector

A power-on-detection (POD) circuit includes first and second comparators, a voltage divider, a detection circuit coupled to a first voltage source node and the voltage divider, and logic circuitry coupled to outputs of the first and second comparators. The detection circuit outputs a control signal identifying if a first voltage source node has a voltage potential that is higher than ground. The control signal turns on and off the first and second comparators, which are respectively coupled to first and second nodes of the voltage divider and to a reference voltage node. The logic circuitry outputs a power identification signal based on the signals received from the outputs of the first and second comparators.

A phase locked loop circuit includes a phase frequency detector, a control circuit, a charge pump, a loop filter, a supply circuit, a ring oscillator, a frequency divider and a voltage detector. The phase frequency detector generates a frequency-increasing signal and a frequency-decreasing signal according to a phase difference between an input signal and a feedback signal. The control circuit generates a first control signal and/or a second control signal according to the frequency-increasing signal and the frequency-decreasing signal. The charge pump generates a current signal according to the first control signal and/or the second control signal. The voltage detector monitors a supply voltage of the supply circuit, and controls the control circuit to generate only the second control signal so as to reduce the supply voltage if the supply voltage is greater than a high reference voltage.

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Xinzhuang, Taiwan

Chun-Chi Chang