An embodiment method for modifying the frequency of a clock signal clocking an integrated circuit supplied by a voltage controller comprises, in response to a command for the modification, varying the frequency of the clock signal at a rate allowing a supply voltage to be controlled by the controller. The variation comprises at least one series of successive divisions of the frequency of the clock signal into successive intermediate signals of respective intermediate frequencies.

Phase-locked loops (PLLs) are provided. A PLL includes a voltage-controlled oscillator (VCO), a frequency divider and a track-and-hold charge pump. The VCO is configured to provide an output clock corresponding to a pumping current. The frequency divider is configured to provide a feedback signal according to the output clock. The track-and-hold charge pump is configured to provide the pumping current according to a reference clock and the feedback signal. The track-and-hold charge pump includes a track-and-hold circuit, a pumping switch and a pulse width modulator (PWM). The track-and-hold circuit is coupled to the frequency divider and configured to sample the feedback signal according to the reference clock. The PWM is configured to provide a PWM signal to control the pumping switch according to the reference clock, so as to provide the pumping current corresponding to the sampled feedback signal.

Phase-locked loops (PLLs) are provided. A PLL includes a voltage-controlled oscillator (VCO), a frequency divider and a track-and-hold charge pump. The VCO is configured to provide an output clock corresponding to a pumping current. The frequency divider is configured to provide a feedback signal according to the output clock. The track-and-hold charge pump is configured to provide the pumping current according to a reference clock and the feedback signal. The track-and-hold charge pump includes a track-and-hold circuit, a pumping switch and a pulse width modulator (PWM). The track-and-hold circuit is coupled to the frequency divider and configured to sample the feedback signal according to the reference clock. The PWM is configured to provide a PWM signal to control the pumping switch according to the reference clock, so as to provide the pumping current corresponding to the sampled feedback signal.

A system includes a digital phase-locked loop (DPLL) having a loop filter and a digitally-controlled oscillator (DCO). The system also includes a clock generator coupled to an output of the DPLL, and a plurality of clock domains coupled to the clock generator. The DPLL is configured to transition between a low power mode and a normal mode, wherein the loop filter is configured to maintain its value when the DPLL transitions from the normal mode to the low power mode. The DCO is configured to output a DCO clock signal based on the maintained loop filter value when the DPLL transitions from the low power mode to the normal mode.

A system includes a digital phase-locked loop (DPLL) having a loop filter and a digitally-controlled oscillator (DCO). The system also includes a clock generator coupled to an output of the DPLL, and a plurality of clock domains coupled to the clock generator. The DPLL is configured to transition between a low power mode and a normal mode, wherein the loop filter is configured to maintain its value when the DPLL transitions from the normal mode to the low power mode. The DCO is configured to output a DCO clock signal based on the maintained loop filter value when the DPLL transitions from the low power mode to the normal mode.

A clock monitoring circuit and an integrated circuit including the clock monitoring circuit, the clock monitoring circuit including a first duty ratio detector that detects a variation of a duty ratio of a clock signal based on a first upper limit voltage and a first lower limit voltage, a second duty ratio detector that detects a variation of a duty ratio of a monitoring clock signal based on a second upper limit voltage and a second lower limit voltage, and a first frequency detector that detects a frequency variation of the clock signal using the second upper limit voltage and the second lower limit voltage.

A clock monitoring circuit and an integrated circuit including the clock monitoring circuit, the clock monitoring circuit including a first duty ratio detector that detects a variation of a duty ratio of a clock signal based on a first upper limit voltage and a first lower limit voltage, a second duty ratio detector that detects a variation of a duty ratio of a monitoring clock signal based on a second upper limit voltage and a second lower limit voltage, and a first frequency detector that detects a frequency variation of the clock signal using the second upper limit voltage and the second lower limit voltage.

The physically unclonable function device (DIS) comprises a set of MOS transistors (TR1i, TR2j) mounted in diodes having a random distribution of respective threshold voltages, and comprising N first transistors and at least one second transistor. At least one output node of the function is capable of delivering a signal, the level of which depends on the comparison between a current obtained using a current circulating in the at least one second transistor and a current obtained using a reference current that is equal or substantially equal to the average of the currents circulating in the N first transistors. A first means (FM1i) is configured to impose on each first transistor a respective fixed gate voltage regardless of the value of the current circulating in the first transistor, and a second means (SM2j) is configured to impose a respective fixed gate voltage on each second transistor regardless of the value of the current circulating in the second transistor.

The physically unclonable function device (DIS) comprises a set of MOS transistors (TR1i, TR2j) mounted in diodes having a random distribution of respective threshold voltages, and comprising N first transistors and at least one second transistor. At least one output node of the function is capable of delivering a signal, the level of which depends on the comparison between a current obtained using a current circulating in the at least one second transistor and a current obtained using a reference current that is equal or substantially equal to the average of the currents circulating in the N first transistors. A first means (FM1i) is configured to impose on each first transistor a respective fixed gate voltage regardless of the value of the current circulating in the first transistor, and a second means (SM2j) is configured to impose a respective fixed gate voltage on each second transistor regardless of the value of the current circulating in the second transistor.

A semiconductor device includes a clock generator which receives an input clock and generates an output clock, a reference voltage generator which receives the input clock or the output clock, generates a sub-reference voltage in accordance with a frequency of the input clock or a frequency of the output clock, and generates a reference voltage using the sub-reference voltage and a preset error voltage, and a clock detector which receives the output clock, generates a first output voltage in accordance with the output clock, and compares the generated first output voltage with the reference voltage to output an error signal based on the output clock, wherein the preset error voltage is set in accordance with a degree of preset error of the output clock.