A frequency divider circuit includes an oscillator comprising a plurality of delay elements coupled in series with each other, a first coupling circuit coupled to a first oscillator node and including a control terminal to receive a first retiming signal, and a first multiplexer including inputs coupled to receive the input signal and a complementary input signal, a control terminal coupled to a second oscillator node, and an output to provide the first retiming signal. The first multiplexer may be configured to alternate between injecting the input signal into the first oscillator node based on rising edges of the input signal and injecting the input signal into the first oscillator node based on falling edges of the input signal in response to a logic state of an oscillation waveform appearing at the second oscillator node.

A semiconductor apparatus may be provided. The semiconductor apparatus may include a first buffer configured to generate a first preliminary clock and a first preliminary clock bar based on an external clock, an external clock bar, and a node voltage code. The semiconductor apparatus may include a node voltage control circuit configured to generate the node voltage code based on a control code.

A frequency divider includes a set of frequency-dividing units coupled in series in a sequential order, with the sequence of frequency-dividing units including a lowest unit and a highest unit, with the remaining units being disposed in series between the lowest unit and the highest unit. The lowest unit is coupled to receive an input clock whose frequency is to be divided and provided as an output clock. Each frequency-dividing unit in the set is coupled to receive a corresponding first clock as an input and is operable to generate a corresponding second clock as an output. The frequency divider includes a logic block to generate a first set of edges of the output clock synchronous with the input clock. The logic block is designed to generate a second set of edges of the output clock synchronous with the output clock of a highest operative frequency-dividing unit in the set.

A resonator oscillator that may be included in a gas sensing system may include an oscillator that may be electrically connected to an external resonator through a conductive line. The oscillator may generate an oscillating signal having a frequency corresponding to a resonance frequency of the external resonator in an oscillating path. A spurious resonance removal circuit on the oscillating path may remove spurious resonance caused by the conductive line from the oscillating path. A gas sensing system may include the oscillator, a resonator that includes a sensor configured to sense a gas, and a frequency counting logic that receives the oscillating signal and a reference clock signal, performs a counting operation on the oscillating signal according to a logic state of the reference clock signal to generate a counted value, and generate a gas sensing output indicating a sensed gas based on the counted value.

A low dropout voltage (LDO) regulator including: a coarse loop circuit configured to receive an input voltage, generate a coarse code and adjust a coarse current according to the coarse code; a digital controller configured to receive the coarse code and generate a fine loop control signal according to the coarse code; and a fine loop circuit configured to receive the input voltage and the fine loop control signal and adjust a fine current according to the input voltage and the fine loop control signal, wherein the coarse current and the fine current adjust a level of an output voltage.

A method for dithering a fractional clock divider includes generating a first clock enable sequence based on a seed pattern of M ones and N minus M zeros, selecting a cyclic rotation of the seed pattern after N input clock cycles, and generating a second clock enable sequence based on the cyclic rotation. A clock gate receives the input clock signal and the clock enable sequences and outputs M clock cycles for every N input clock cycles. A random number generator indicates the cyclic rotation of the seed pattern. The seed pattern can be replaced with an updated seed pattern of M ones and N minus M zeros in a different order. In some examples, the clock enable sequence is generated using a cyclic shift register containing the seed pattern and a multiplexor. In other examples, the clock enable sequence is generated using a modulo N counter and a comparator.

A method for reducing deterministic jitter in a clock generator includes providing a load current through a regulated voltage node to a circuit responsive to a divide ratio. The method includes providing an auxiliary current through the regulated voltage node. The auxiliary current has a first current level during a first period corresponding to a first value of the divide ratio and the auxiliary current has a second current level during a second period corresponding to a second value of the divide ratio.

Various embodiments relate to multi-modulus frequency dividers, devices including the same, and associated methods of operation. A method of operating a multi-modulus divider (MMD) may include receiving, at the MMD, an input signal at a first frequency. The method may also include generating, via the MMD, an output signal at a second, lower frequency based on a divisor value. Further, the method may include receiving, at the MMD, an integer value. Moreover, the method may include setting the divisor value equal to the integer value in response to a current state of the MMD matching a common state for the MMD, wherein the MMD is configured to enter the common state regardless of the divisor value.

A method for dithering a fractional clock divider includes generating a first clock enable sequence based on a seed pattern of M ones and N minus M zeros, selecting a cyclic rotation of the seed pattern after N input clock cycles, and generating a second clock enable sequence based on the cyclic rotation. A clock gate receives the input clock signal and the clock enable sequences and outputs M clock cycles for every N input clock cycles. A random number generator indicates the cyclic rotation of the seed pattern. The seed pattern can be replaced with an updated seed pattern of M ones and N minus M zeros in a different order. In some examples, the clock enable sequence is generated using a cyclic shift register containing the seed pattern and a multiplexor. In other examples, the clock enable sequence is generated using a modulo N counter and a comparator.

The disclosure discloses a lookup table-based circuit aging detection sensor, including a control circuit, two voltage controlled oscillators (VCOs), two shaping circuits, a phase comparator, a 3-digit voter, a beat-frequency oscillator, an 8-digit counter, a latch, a lookup table array and a digital-analogue converter. The control circuit respectively connects with the phase comparator, the 3-digit voter, the 8-digit counter, the first and the second VCOs. The first and second VCOs connect with the first and second shaping circuits respectively. The first and second shaping circuits connect with the phase comparator. The phase comparator connects with the 3-digit voter. The 3-digit voter connects with the beat-frequency oscillator. The beat-frequency oscillator respectively connects with the 8-digit counter and the latch. The 8-digit counter connects with the latch. The latch connects with the lookup table array. The lookup table array connects with the digital-analogue converter.