摘要:
A transmitter circuit is operable to provide an output signal in response to a first periodic signal. A multiplexer circuit is operable to provide a second periodic signal as a selected signal during a first phase of operation. The multiplexer circuit is operable to provide the output signal of the transmitter circuit as the selected signal during a second phase of operation. A sampler circuit is operable to generate first samples of the selected signal during the first phase of operation. The sampler circuit is operable to generate second samples of the selected signal during the second phase of operation. A duty cycle control circuit is operable to adjust a duty cycle of the first periodic signal based on the first and the second samples.
摘要:
Signal detection circuitry for a serial interface oversamples the input—i.e., samples the input multiple times per clock cycle—so that the likelihood of missing a signal is reduced. Sampling may be done with a regenerative latch which has a large bandwidth and can latch a signal at high speed. The amplitude threshold for detection may be programmable, particularly in a programmable device. Thus, between the use of a regenerative latch which is likely to catch any signal that might be present, and the use of oversampling to avoid the problem of sampling at the wrong time, the likelihood of failing to detect a signal is greatly diminished. Logic, such as a state machine, may be used to determine whether the samples captured s do or do not represent a signal. That logic may be programmable, allowing a user to set various parameters for signal detection.
摘要:
A phase interpolator circuit can include first and second transistors coupled to form a differential pair, first and second load circuits, a first switch circuit coupled between the first transistor and the first load circuit, a second switch circuit coupled between the second transistor and the second load circuit, a current source circuit, and a third switch circuit coupled between the differential pair and the current source circuit. A phase interpolator circuit can include three differential pairs of transistors. Six periodic input signals having six different phases are concurrently provided to control inputs of transistors in the three differential pairs of transistors. The phase interpolator circuit generates a selected phase in an output signal in response to four of the periodic input signals.
摘要:
A programmable logic device integrated circuit (“PLD”) includes high-speed serial interface (“HSSI”) circuitry in addition to programmable logic circuitry. The HSSI circuitry includes multiple channels of nominal data-handling circuitry (typically including clock and data recovery (“CDR”) circuitry), and at least one channel of nominal clock management unit (“CMU”) circuitry (typically including phase-locked loop (“PLL”) circuitry or the like). To increase the flexibility with which the channels can be used, the nominal data-handling channels are equipped to alternatively perform CMU-type functions, and the nominal CMU channel is equipped to alternatively perform data-handling functions.
摘要:
Techniques are provided for compensating for phase and timing delays in clock signals generated by phase-locked loops and delay-locked loops on integrated circuits. Circuit elements coupled in a feedback loop of a locked circuit can compensate for the timing and phase delays between an input pin and an output pin. Other circuit elements coupled in the feedback loop of a locked circuit can compensate for the delay between an input pin and a destination circuit element. Still other circuit elements coupled in an input reference path of a locked circuit preserve a timing relationship between input clock and input data signals. A clock signal and a data signal received at a destination circuit element have the same phase and timing relationship that exists between the input clock and input data signals at input pins.
摘要:
A loss-of-signal detector includes digital and analog monitoring of incoming data. The incoming signal is compared digitally to at least one predetermined pattern that may indicate a loss of signal, and also is monitored by an analog detector that detects transitions in the data. If the digital comparison fails to match any of the at least one predetermined pattern, or if transitions are detected by the analog monitoring, even if the digital comparison produces a pattern match, then loss of signal is not indicated.
摘要:
Voltage controlled oscillator (VCO) circuitry with low phase noise and a wide range of operating frequencies is presented. The VCO circuitry includes circuitry with two or more VCO sub-circuits, each sub-circuit being optimized to produce output clock signals with low phase noise and with frequencies in a different range. Sub-circuits with gear inputs may be operative to produce output clock signals in a lower range of frequencies, while sub-circuits optimized for high speed operation may be used to produce output signals in a higher range of frequencies. A control circuit may be used to produce a control signal coupled to all sub-circuits. The control signal may set the operating frequency of the sub-circuits.
摘要:
Integrated circuits having transceivers capable of high-speed (e.g., 1 Gbps) operation without dedicated phase-locked loop circuitry are provided. One such integrated circuit device may include one or more transceivers capable of transmitting and receiving serial signals of approximately 1 Gbps or greater, and a multi-purpose phase-locked loop capable of providing a multi-phase clock signal to the one or more transceivers.
摘要:
One embodiment relates to an integrated circuit which includes multiple communication channels, a clock multiplexer in each channel, two low-jitter clock generator circuits, and clock distribution circuitry. Each channel includes circuitry arranged to communicate a serial data stream using a reference clock signal, and the clock multiplexer in each channel is configured to select the reference clock signal from a plurality of input clock signals. The first low-jitter clock generator circuit is arranged to generate a first clock signal using a first inductor-capacitor-based oscillator circuit, and the second low-jitter clock generator circuit is arranged to generate a second clock signal using a second inductor-capacitor-based oscillator circuit The first and second inductor-capacitor-based oscillator circuits have different tuning ranges. The clock distribution circuitry is arranged to input the first and second low-jitter clock signals to each said clock multiplexer. Other embodiments and features are also disclosed.
摘要:
A circuit includes a phase detection circuit, a phase adjustment circuit, and a sampler circuit. The phase detection circuit compares a phase of a first periodic signal to a phase of a second periodic signal to generate a control signal. The phase adjustment circuit causes the phase of the second periodic signal and a phase of a third periodic signal to vary based on a variation in the control signal. The sampler circuit samples a data signal to generate a sampled data signal in response to the third periodic signal. The circuit varies a frequency of the third periodic signal to correspond to changes in a data rate of the data signal between at least three different data rates that are based on at least three data transmission protocols.