A system receives a first clock signal with a first frequency and a second clock signal having a second frequency lower than the first frequency. The system generates a new second clock signal aligned with the first clock signal based on a known phase/frequency relationship between the clock signals. A counter counts cycles of the first clock signal. The system generates a new second clock signal with an edge aligned with a first clock signal when the counter reaches a predetermined count value and the system resets the counter. A window opens that includes a time period when the edge of the first clock signal is expected. If an edge of the first clock signal is detected outside of the window, the counter is reset responsive to the detected edge.

A duty adjustment circuit, and a delay locked loop circuit and a semiconductor memory device including the same are provided. The duty adjustment circuit includes a pulse generator configured to generate a pulse signal at a constant pulse width regardless of a frequency of a reference clock signal, based on frequency information, a code generator configured to generate a first predetermined number of delayed pulse signals by delaying the pulse signal, as a first code in response to the pulse signal, and a duty adjuster configured to receive a delay clock signal, and generate a duty correction clock signal by adjusting a slope of rising transition and a slope of falling transition of the delay clock signal in response to the first code and a second code.

Duty cycle adjustment circuitry includes a first stage, a second stage, and decoder circuitry. The first stage includes a first strength tuning circuit having first inverter branches, and a first fine tuning circuit having second inverter branches. The first strength tuning circuit and the first fine tuning circuit are coupled in parallel. The second stage includes a second strength tuning circuit having third inverter branches, and a second fine tuning circuit having fourth inverter branches. The second strength tuning circuit and the second fine tuning circuit are coupled in parallel. Further, the second stage is electrically coupled to the first stage. The decoder circuitry is electrically coupled to the first stage and the second stage. The decoder circuitry controls the first strength tuning circuit independently from the first fine tuning circuit to adjust the duty cycle of an input signal received by the duty cycle adjustment circuitry.

The inventive concepts relate to methods for duty cycle correction of an input signal and circuits thereof. The method comprising following operations of generating, a plurality of intermediate delayed input signals, each delayed by at least a unit delay, through a delay line driven by the input signal, selecting from among the plurality of delayed input signals, through a first control signal, where the selection is based on number of unit delays in the input signal, generating at least an incremented duty signal and a decremented duty signal based on the selected delayed signals and the input signal, generating, a corrected duty cycle based on the selection of at least one of: the incremented duty cycle or decremented duty cycle by providing a second control signal. The inventive concepts offer low power consumption and low area for correction or adjustment of the duty cycle of the input signal with higher probability or guaranteed monotonicity.

Described are apparatus and methods for fractional synchronization using direct digital frequency synthesis (DDFS). A DDFS device includes a memory with N address spaces, a write port circuit configured to sequentially write a digital desired pattern into the N address spaces, a read port circuit configured to readout the digital desired pattern from the N address spaces using continuous sequential automatic addressing from 0 to N−1 at a memory operating frequency clock, where the memory operating frequency clock is based on a sampling frequency clock used for high-speed data processing, and an analog signal processing circuit configured to process a readout digital desired pattern into an analog representation; and output a synthesized frequency clock from the analog representation to a digital core, where the synthesized frequency clock is fractionally synchronized with the sampling frequency clock.

Provided are a spread spectrum clock generator and a spread spectrum clock generation method, a pulse pattern generator and a pulse pattern generation method, and an error rate measuring device and an error rate measuring method capable of improving usability when adjusting a waveform of a modulation signal during training. A setting screen 60 includes a 0-th frequency shift input unit 71 for arbitrarily setting a frequency shift of a waveform of a modulation signal in a plurality of time sections, a first frequency shift input unit 72, a second frequency shift input unit 73, a third frequency shift input unit 74, and a modulation selection unit 67 for switching a waveform pattern of the modulation signal from a first pattern to a second pattern.

Provided are a spread spectrum clock generator and a spread spectrum clock generation method, a pulse pattern generator and a pulse pattern generation method, and an error rate measuring device and an error rate measuring method capable of improving usability when adjusting a waveform of a modulation signal during training. A setting screen 60 includes a 0-th frequency shift input unit 71 for arbitrarily setting a frequency shift of a waveform of a modulation signal in a plurality of time sections, a first frequency shift input unit 72, a second frequency shift input unit 73, a third frequency shift input unit 74, and a modulation selection unit 67 for switching a waveform pattern of the modulation signal from a first pattern to a second pattern.

Digital to analog converter generates an analog output corresponding to a digital input by controlling DAC cells using bits of the digital input. The DAC cells individually make a contribution to the analog output. Due to process, voltage, and temperature variations, the DAC cells may have duty cycle error or mismatches. To compensate for the duty cycle error of a DAC cell, a small amount of charge is injected into a low-impedance node of a DAC cell when the data signal driving the DAC cell transitions, or changes state. The small amount of charge is generated using a capacitive T-network, and the polarity of the charge injected is opposite of the error charge caused by duty cycle error. The opposite amount of charge thus compensates or cancels out the duty cycle error, and duty cycle error present at the output of the DAC cell is reduced.

Disclosed herein are related to systems and methods for correcting non-linearity due to duty cycle error. In one aspect, a system includes a mixer configured to up-convert transmission (Tx) data, a coefficient calibrator configured to select a target value of a coefficient based on a measurement of an interference signal due to non-linearity of the mixer, and an interference canceller coupled to the coefficient calibrator and the mixer. In some embodiments, the interference canceller is configured to generate compensated Tx data based on the Tx data and the selected target value of the coefficient and provide the compensated Tx data to the mixer. In some embodiments, the compensated Tx data corrects for the non-linearity of the mixer.

A duty cycle correction circuit (DCCC) for a multi-modulus frequency divider, the DCCC comprising: a corrector chain comprising a plurality of flip-flops each configured to receive one of the internal signals; and at least one delay selection logic element, each configured to receive an output signal from different ones of the flip-flops and the output of each delay selection logic element is based on the received output signal and the division factor; the DCCC is configured such that: a first state change in its output signal is defined by a transition to a first logic state of one of the internal signals; and a second state change in its output signal is based on a transition to a second logic state of one of the internal signals after a delay period, wherein the duty cycle of the output signal is based on the delay period.