In a system for performing clock generation for each semiconductor device, synchronization between the semiconductor devices is achieved without causing a count value in a counter to be discontinuously changed. A semiconductor device 1 includes a clock oscillator 2, a counter 3 configured to count the number of clocks, a periodic register 4 in which a value corresponding to a period for synchronization is set, a comparison circuit 5 configured to compare the count value in the counter 3 with the set value in the periodic register 4, a match flag register 6 in which a predetermined value is set when the count value coincides with the set value, a match output terminal 7 configured to output the value in the match flag register 6 from the own semiconductor device, a match input terminal 8 to which a value output from another semiconductor device to be synchronized is input, and a reset circuit configured to reset the counter 3 and the match flag register 6 when both the value in the match flag register 6 of the own semiconductor device and the value input to the match input terminal 8 become a predetermined value.

A method for detecting a latent failure mode in an electronic selector having an interface switch and at least two underlying switches includes tracking and counting each of the underlying switch's close/open status change counts in the context of tracking and counting the interface switch selection status change counts. The method continues by calculating the ratio of each underlying switch's close or open status change counts against the interface switch selection status change counts. By comparing these ratios from each underlying switch in respect to the interface switch selection status change counts, a set of new algorithms are formulated to detect an interface switch latent failure mode due to either one of the at least two underlying switches stuck to open or one of the at least two underlying switches chattering between close and open states at a relatively high frequency compared to the interface switch selection event.

A digital frequency measuring apparatus includes a frequency divider dividing an input frequency signal and providing a divided frequency signal; a period counter counting clock cycles in a period of the divided frequency signal using a clock signal and providing a period count value for each period; and a digital filter amplifying the period count value using an accumulated gain, converting an amplified period count value into a frequency, and providing a first digital output value. The digital filter determines the accumulated gain using a predetermined stage number and a predetermined decimator factor.

A digital frequency measuring apparatus includes a frequency divider dividing an input frequency signal and providing a divided frequency signal; a period counter counting clock cycles in a period of the divided frequency signal using a clock signal and providing a period count value for each period; and a digital filter amplifying the period count value using an accumulated gain, converting an amplified period count value into a frequency, and providing a first digital output value. The digital filter determines the accumulated gain using a predetermined stage number and a predetermined decimator factor.

Upon a first transition from a first state to a second state, a first bit in a memory unit comprising a plurality of bits is programmed. Upon a first transition from the second state to the first state, a second bit in the memory unit is programmed, the second bit being before the first bit in the sequence of the plurality of bits. Upon a second transition from the first state to the second state, a third bit in the memory unit is programmed, the third bit being subsequent to the first bit by at least two bits in the sequence of the plurality of bits. Upon a second transition from the second state to the first state, a fourth bit in the memory unit is programmed, the fourth bit being before the third bit in the sequence of the plurality of bits.

Frequency divider techniques are disclosed which can be used to address two problems: when an incorrect division occurs if the modulus control changes before the divide cycle is complete, and when an incorrect division occurs due to a boundary crossing (e.g., power-of-2 boundary crossing in a fractional-N PLL application). In one embodiment, a frequency divider is provided comprising a plurality of flip-flops operatively coupled to carry out division of an input frequency, and configured to generate a modulus output and receive a divided clock signal of a previous cell. An additional flip-flop is selectively clocked off one of the modulus output or the divided clock of the previous stage, depending at least in part on a Skip control signal applied to a data input of the additional flip-flop, and is further configured to selectively reset the plurality of flip-flops to a state that will result in a correct divide ratio.

A method for detecting a latent failure mode in an electronic selector having an interface switch and at least two underlying switches includes tracking and counting each of the underlying switch's close/open status change counts in the context of tracking and counting the interface switch selection status change counts. The method continues by calculating the ratio of each underlying switch's close or open status change counts against the interface switch selection status change counts. By comparing these ratios from each underlying switch in respect to the interface switch selection status change counts, a set of new algorithms are formulated to detect an interface switch latent failure mode due to either one of the at least two underlying switches stuck to open or one of the at least two underlying switches chattering between close and open states at a relatively high frequency compared to the interface switch selection event.

The present invention provides a fractional frequency divider, wherein the fractional frequency divider includes a plurality of registers, a counter, a control signal generator and a clock gating circuit. Regarding the plurality of registers, at least a portion of the registers are set to have values The counter is configured to sequentially generate a plurality of counter values, wherein the plurality of counter values correspond to the at least a portion of the registers, respectively, and the plurality of counter values are generated repeatedly The control signal generator is configured to generate a control signal based on the received counter value and the value of the corresponding register. The clock gating circuit is configured to refer to the control signal to mask or not mask an input clock signal to generate an output clock signal.

A method of storing a counter in at least two non-volatile memory pages, including: a step of initializing a page with an initial value and then, on each update of the counter value, a step of storing an update value and an opcode associated with this value, selected from a set of opcodes, the current value of the counter being given by application of the successive update operations to the initial value of the page.

A semiconductor device including an oscillator configured to output a first signal, and circuitry configured to count a cycle number of the first signal OSC. Before the oscillator outputs an N-th (N is an integer equal to or larger than 2) cycle of the first signal, the circuitry changes a count value of the cycle number of the first signal to N.