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.

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.

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.

A semiconductor integrated circuit includes a first oscillator configured to generate a first signal with a first frequency based on a control signal and output the first signal to a path. The semiconductor integrated circuit includes a control signal generation circuit operatively coupled to the first oscillator via the path, and configured to receive the first signal from the first oscillator via the path and generate the control signal. The semiconductor integrated circuit includes a second oscillator configured to generate a second signal with a second frequency based on the control signal and output the second signal to an output terminal outside the path.

A test and measurement instrument includes a first data channel including a first data converter operating at a first rate, and a second data channel including a second data converter operating at a second rate that is different than the first rate. Rate controls may include a clock generation circuit. The clock generation circuit includes an intermediate frequency generator structured to generate an intermediate frequency clock from a first clock reference signal, a first frequency clock generator structured to generate a first frequency clock directly from the intermediate frequency clock, and a second frequency clock generator structured to generate a second frequency clock directly from the intermediate frequency clock. The first frequency clock may be used to control the rate of the first data channel, and the second frequency clock may be used to control the rate of the second data channel. Methods are also described.

A test and measurement instrument includes a first data channel including a first data converter operating at a first rate, and a second data channel including a second data converter operating at a second rate that is different than the first rate. Rate controls may include a clock generation circuit. The clock generation circuit includes an intermediate frequency generator structured to generate an intermediate frequency clock from a first clock reference signal, a first frequency clock generator structured to generate a first frequency clock directly from the intermediate frequency clock, and a second frequency clock generator structured to generate a second frequency clock directly from the intermediate frequency clock. The first frequency clock may be used to control the rate of the first data channel, and the second frequency clock may be used to control the rate of the second data channel. Methods are also described.

An IC, operable at a first clock phase, includes first and second IOs and a PLL. The PLL includes a control circuit, an input to receive a first clock signal, an output to output a second clock signal, and a first detector to generate a first phase difference signal from the first and second clock signals. The IC includes a second phase detector that is coupled to the PLL's output to receive the second clock signal and is coupled to the first IO to receive a third clock single from a second IC, which is operable at a second clock phase. The second detector generates a second phase difference signal from the second and third clock signals. If the PLL uses the second phase difference signal to generate the second clock signal, then the second clock signal is synchronized with the third clock signal for synchronous data transfer.

An IC, operable at a first clock phase, includes first and second IOs and a PLL. The PLL includes a control circuit, an input to receive a first clock signal, an output to output a second clock signal, and a first detector to generate a first phase difference signal from the first and second clock signals. The IC includes a second phase detector that is coupled to the PLL's output to receive the second clock signal and is coupled to the first IO to receive a third clock single from a second IC, which is operable at a second clock phase. The second detector generates a second phase difference signal from the second and third clock signals. If the PLL uses the second phase difference signal to generate the second clock signal, then the second clock signal is synchronized with the third clock signal for synchronous data transfer.

The present invention discloses a transceiver apparatus having phase-tracking mechanism. A phase detection circuit of a receiver circuit performs sampling and phase detection on an input data signal according to a sampling clock signal to generate a phase detection result. A proportional gain circuit of the receiver circuit applies a proportional gain operation on the phase detection result to generate a phase adjusting signal. A CDR circuit of the receiver circuit receives a source clock signal to generate the sampling clock signal and performs phase-adjusting according to the phase adjusting signal. The integral gain circuit apples an integral gain operation on the phase detection result to generate a frequency adjusting signal. The source clock generating circuit receives a reference clock signal to generate the source clock signal and perform frequency-adjusting according to the frequency adjusting signal. The transmitter circuit performs signal transmission according to the source clock signal.

A noise detection circuit includes a first transistor configured to receive a delayed version of a clock signal; a second transistor configured to receive a delayed version of a reference clock signal; and a latch circuit, coupled to the first transistor at a first node and coupled to the second transistor at a second node, and configured to latch logic states of voltage levels at the first and second nodes, respectively, based on whether a timing difference between transition edges of the clock signal and the reference clock signal exceeds a pre-defined timing offset threshold.