An apparatus can implement a frequency doubler with duty cycle correction in conjunction with, for instance, a phase-locked loop (PLL) to decrease phase noise. In an example aspect, an apparatus has a frequency doubler including a signal combiner, a first signal pathway, and a second signal pathway. The frequency doubler also includes a doubler input node and a doubler output node. The signal combiner is coupled to the doubler output node. The first signal pathway is coupled between the doubler input node and the signal combiner and includes a first adjustable delay cell. The second signal pathway is also coupled between the doubler input node and the signal combiner and includes a second adjustable delay cell.

A duty-cycle corrector circuit produces a clock signal with a given duty cycle (e.g., fifty percent) or with a substantially given duty cycle. The DC corrector circuit includes a delay-locked loop (DLL) circuit and a duty-cycle correction (DCC) circuit. The DLL circuit is operable to adjust a delay between local clock signals until the phase difference between the local clock signals equals or is substantially equal to zero. The DCC circuit is operable to adjust the duty cycles of the local clock signals until the duty-cycle error equals or is substantially equal to zero. The duty-cycle error equals or substantially equals zero when the duty cycles of the local clock signals equal or are substantially equal to fifty percent.

A DLL circuit that has a programmable output frequency is provided. The DLL circuit uses a single delay line to produce the multiple frequencies. In various embodiments, the delay line is configured to receive an input clock defining an input clock period. The delay line comprises delay stages, each configured to generate a corresponding output clock having a phase relative to the input clock based on a delay of the delay line. In those embodiments, a control circuit is configured to change the delay of the delay line so as to cause a phase difference between the input clock and a sensed output clock to be substantially equal to the input clock period. An edge combiner is configured to generate a DLL output clock based on the output clocks of the delay stages and presents an equal schematic load for each of the output clocks of the delay stages.

One embodiment of a duty-cycle corrector phase shift (DCCPS) circuit includes a voltage-controlled delay line circuit, a duty-cycle correct circuit, an error amplifier circuit, and DC sampler circuits. Another embodiment of a duty-cycle corrector phase shift circuit includes a digital-controlled delay line circuit, a duty-cycle correct circuit, DC sampler circuits, a comparator circuit, a counter circuit, a control circuit, and a lock detector circuit. In some instances, the DCCPS circuit provides a clock signal with a duty-cycle of approximately fifty percent (50%) and a given phase shift between an input clock signal and the output clock signal.

Apparatuses and methods of DLL measurement initialization are disclosed. An example apparatus includes: a clock enable circuit that provides a first clock signal having a half frequency of an input clock signal and second clock signals having a quarter frequency of the input clock signal; a coarse delay that provides the first clock signal with a coarse delay; a fine delay that provides the first clock signal with the coarse delay and a fine delay as an output clock signal; a model delay having a feedback delay equivalent to a sum of delays of an input stage and an output stage, and provides a feedback signal that is the output clock signal with the feedback delay; and a measurement initialization circuit that performs measurement initialization. The measurement initialization circuit includes synchronizers that receive the feedback signal and the second clock signals, and provide a stop signal to the coarse delay.

A DLL includes a delay line with two phase outputs, a gater coupled with the delay line phase outputs, a PFD coupled with gater outputs, a PD coupled with PFD outputs, a retimer coupled with PD outputs, and a loop filter with inputs coupled with the retimer and a speed control output coupled with the delay line. The gater passes signals on its two inputs to its two outputs, apart from a first pulse on its first input. The PD determines if the second gated signal leads or lags the first gated signal. The retimer retimes PD output signals to be aligned with a delay line input signal. The loop filter uses the retimed PD output signals to determine if the delay line should delay more or delay less, and outputs a speed control signal to control the delay line speed.

A delay locked loop circuit includes a first delay locked loop and a second delay locked loop having different characteristics. The first delay locked loop performs a delay-locking operation on a reference clock signal to generate a delay locked clock signal. The second delay locked loop performs a delay-locking operation on the delay locked clock signal to generate an internal clock signal.

The present disclosure relates to the technical field of integrated circuits, and specifically to a delay-locked loop, a control method for a delay-locked loop, and an electronic device. The delay-locked loop includes: a secondary path configured to perform frequency division on an input clock signal to generate a frequency-divided clock signal, adjust the frequency-divided clock signal having a first frequency to obtain an output clock signal in a locking process of the delay-locked loop, and adjust the frequency-divided clock signal to make the frequency-divided clock signal have a second frequency when the delay-locked loop is locked in a standby state, wherein the second frequency is lower than the first frequency; and a primary path configured to output, when obtaining a target instruction, an output clock replica signal having a same phase as the output clock signal.

A delay-locked loop (DLL) and corresponding method improve frequency of a chip. The DLL comprises a first programmable delay element configured to output a first clock, a second programmable delay element configured to output a second clock a phase detector. The phase detector includes a first clock input and a second clock input. The first and second programmable delay elements are further configured, in combination, to introduce a controllable skew between the first and second clocks. The DLL is configured to input the first and second clocks to the first and second clock inputs of the phase detector, respectively. The controllable skew is configured to improve the frequency of the chip.

An initialization circuit of a delay locked loop (DLL) includes a sense circuit and a control circuit. The sense circuit receives an enable signal, a reference clock signal, and various delayed reference clock signals, and outputs another enable signal. The control circuit receives the two enable signals and outputs and provides a control signal to a loop filter of the DLL to control a delay value associated with the DLL. The control signal is provided to the loop filter such that the delay value associated with the DLL equals a predetermined delay value for a predetermined time duration. Further, after a lapse of the predetermined time duration, the delay value associated with the DLL increases until a difference between a time period of the reference clock signal and the delay value equals a threshold value.