Various implementations described herein refer to an integrated circuit having first clock circuitry that receives a first clock signal and provides sampled offset pulses associated with the first clock signal when enabled with enable signals. The integrated circuit may include second clock circuitry that receives a second clock signal and provides the enable signals to the first clock circuitry based on the second clock signal. The integrated circuit may include fault detector circuitry that receives the sampled offset pulses from the first clock circuitry, receives the enable signals from the second clock circuitry, and provides one or more error flags for detected faults of the first clock signal based on the sampled offset pulses from the first clock circuitry and based on the enable signals from the second clock circuitry.

A clock fractional divider module which is formed as, comprises or has integrated therein a dual-core lock step unit. The dual-core lock step unit is configured in order to realize a clock fractional division arrangement, mechanism or process accompanied by an error detection, recognition and/or correction arrangement, mechanism or process.

A clock monitor includes a test clock input, as a reference clock input, another clock input, a measurement circuit, and control logic. The measurement circuit generates a measurement of a frequency or a duty cycle of the test clock input using the reference clock input, which is compared to a threshold. The control logic determines whether the measurement exceeded the threshold and, based on the measurement exceeding the threshold, cause generation of another measurement of a frequency or a duty cycle using the third clock input in combination with the first clock input or the reference clock input. The control logic may determine whether the other measurement exceeded a threshold and, based on such a determination, further determine that the test clock input or the reference clock input are faulty.

The disclosed embodiments relate to components of a memory system that support timing-drift calibration. In specific embodiments, this memory system contains a memory device (or multiple devices) which includes a clock distribution circuit and an oscillator circuit which can generate a frequency, wherein a change in the frequency is indicative of a timing drift of the clock distribution circuit. The memory device also includes a measurement circuit which is configured to measure the frequency of the oscillator circuit.

A clock generation circuit and a clock signal generation method are disclosed. In the method, a direct current bias circuit in a first clock source superimposes a first direct current voltage on a first clock signal output by a first oscillation circuit, to generate a second clock signal; and a logical operation is performed on the second clock signal and a third clock signal that is generated by a second clock source, to generate a fourth clock signal. The fourth clock signal is used as a signal output by a clock generation circuit. In the method, when the first oscillation circuit cannot normally work, the clock generation circuit can still output a correct clock signal. This avoids clock signal interruption when switching is performed from the first clock source to the second clock source.

A calibration controller of a receiving chip learns a difference between a first clock phase of an input clock for controlling inputs on a data path to a buffer of the receiving chip at a clock boundary and a second clock phase of a chip clock for controlling outputs from the buffer on the data path at the clock boundary. The calibration controller dynamically adjusts a phase of a reference clock driving a phase locked loop that outputs the chip clock to adjust the second clock phase of the chip clock with respect to the first clock phase to minimize a latency on the data path at the clock boundary to a half a cycle granularity.

Apparatus comprises master counter circuitry to generate a master count signal in response to a clock signal; slave counter circuitry responsive to the clock signal to generate a respective slave count signal, the slave counter circuitry having associated fault detection circuitry; and a synchronisation connection providing signal communication between the master counter circuitry and the slave counter circuitry, the master counter circuitry being configured to provide via the synchronisation connection: initialisation data at an initialisation operation; and fault detection data at a fault detection operation; the initialisation data and subsequent fault detection data each representing respective indications of a state of the master count signal; the slave counter circuitry being configured, during an initialisation operation for that slave counter circuitry, to initialise a counting operation of that slave counter circuitry in response to the initialisation data provided by the master counter circuitry; and the fault detection circuitry associated with the slave counter circuitry being configured, during a fault detection operation for that slave counter circuitry, to detect whether a counting operation of that slave counter circuitry generates a slave count signal which is within a threshold count difference of a fault detection count value dependent upon the fault detection data provided by the master counter circuitry.

In accordance with an embodiment, a system includes an oscillator equipped circuit having an oscillator control circuit configured to be coupled to an external oscillator and a processing unit comprising a clock controller. The clock controller includes an interface circuit configured to exchange handshake signals with the oscillator control circuit, a security circuit configured to receive the external oscillator clock signal and configured to select the external oscillator clock signal as the system clock, and a detection block configured to detect a failure in the external oscillator clock signal. Upon detection of the failure, a different clock signal is selected as the system clock and the interface circuit to interrupts a propagation of the external oscillator.

Disclosed clock recovery modules provide improved performance with only limited complexity and power requirements. In one illustrative embodiment, a clock recovery method includes: oversampling a receive signal to obtain mid-symbol interval (MSI) samples and between-symbol interval (BSI) samples; processing at least the MSI samples to obtain symbol decisions; filtering the symbol decisions to obtain BSI targets; determining a timing error based on a difference between the BSI samples and the BSI targets; and deriving from the timing error a clock signal for said oversampling.

Various implementations described herein refer to an integrated circuit having first clock circuitry that receives a first clock signal and provides sampled offset pulses associated with the first clock signal when enabled with enable signals. The integrated circuit may include second clock circuitry that receives a second clock signal and provides the enable signals to the first clock circuitry based on the second clock signal. The integrated circuit may include fault detector circuitry that receives the sampled offset pulses from the first clock circuitry, receives the enable signals from the second clock circuitry, and provides one or more error flags for detected faults of the first clock signal based on the sampled offset pulses from the first clock circuitry and based on the enable signals from the second clock circuitry.