Abstract: An IC that includes a jitter generator, where the jitter generator is integral with the IC and generates non-intrinsic jitter, is provided. In one implementation, the non-intrinsic jitter is used to measure a characteristic of the IC. In one implementation, the non-intrinsic jitter is used to test jitter tolerance of the IC. In yet another implementation, the non-intrinsic jitter is used to test another IC coupled to the IC that includes the jitter generator.

Abstract: One embodiment relates to a receiver circuit for multi-level amplitude signaling which includes at least three amplitude levels for each symbol period. The receiver circuit includes a peak detector, a reference voltage generator, and a comparator circuit. The peak detector is arranged to detect a peak voltage of the multi-level amplitude signal, and the reference voltage generator uses the peak voltage to generate multiple reference voltages. The comparator circuit uses the multiple reference voltages to detect an amplitude level of the multi-level amplitude signal. Other embodiments and features are also disclosed.

Abstract: System, methods, and devices for determining an eye diagram of a serial input signal to an integrated circuit without an oscilloscope are provided. For example, one embodiment of an integrated circuit device may be capable of determining an eye diagram associated with a serial input signal either during or after equalization. The device may include an equalizer and eye viewer circuitry configured to select a node of the equalizer for eye monitoring of the input signal, which may be during or after equalization. In one embodiment, the eye viewer circuitry may provide a separate sampler for each respective node, while sharing a control logic and phase interpolator among the samplers. The eye viewer circuitry may determine horizontal and vertical boundaries of the eye diagram associated with the serial input signal, as seen from the selected node of the equalizer.

Abstract: Transmitter equalizer circuitry, e.g., for a serial, digital, data signal, includes tapped delay line circuitry for outputting a plurality of differently delayed versions of the signal propagating through the delay line circuitry. The equalizer circuitry also includes a plurality of electrical current digital-to-analog converters (“DACs”). The equalizer circuitry still further includes controllable (e.g., programmable) routing circuitry for selectably routing the delayed versions of the signal to the various DACs. The current strengths employed by the various DACs are also preferably controllable (e.g., programmable).

Abstract: A high-speed differential comparator circuit is provided with an accurately adjustable threshold voltage. Differential reference voltage signals are provided to control the threshold voltage of the comparator. The common mode voltage of the reference signals preferably tracks the common mode voltage of the differential high-speed serial data signal being processed by the comparator circuit.

Abstract: An integrated circuit (“IC”) includes circuitry for use in testing a serial data signal. One such IC includes circuitry for transmitting the serial data signal with optional jitter, optional noise, and/or controllably variable drive strength. One such IC also includes circuitry for receiving the serial data signal and performing a bit error rate (“BER”) analysis in such a signal. Such an IC provides output signals indicative of results of its operations. One such IC operates in various modes to perform or at least emulate functions of an oscilloscope, a bit error rate tester, etc., for testing signals and circuitry with respect to jitter-tolerance, noise-tolerance, etc.

Abstract: One embodiment relates to a receiver circuit for multi-level amplitude signaling which includes at least three amplitude levels for each symbol period. The receiver circuit includes a peak detector, a reference voltage generator, and a comparator circuit. The peak detector is arranged to detect a peak voltage of the multi-level amplitude signal, and the reference voltage generator uses the peak voltage to generate multiple reference voltages. The comparator circuit uses the multiple reference voltages to detect an amplitude level of the multi-level amplitude signal. Other embodiments and features are also disclosed.

Abstract: Systems, methods, and devices for determining an eye diagram of a serial input signal to an integrated circuit without an oscilloscope are provided. For example, one embodiment of an integrated circuit device may be capable of determining an eye diagram associated with an equalized serial input signal. The device may include an equalizer and eye viewer circuitry. The equalizer may receive and perform equalization on a serial input signal to produce the equalized serial input signal, and the eye viewer circuitry may determine horizontal and vertical boundaries of the eye diagram associated with the equalized serial input signal.

Abstract: An IC that includes an eye viewer and a BER checker coupled to the eye viewer, where the BER checker receives a serial data signal from the eye viewer, is provided. In one implementation, the BER checker receives the serial data signal from the eye viewer without the serial data signal passing through a deserializer. In one implementation, the BER checker compares the serial data signal against a reference data signal to determine the BER for the serial data signal. In one implementation, the IC includes an IC core coupled to the eye viewer and the BER checker, where the BER checker is outside the IC core. In one implementation, the BER checker is a dedicated BER checker. In one implementation, the BER checker includes an exclusive OR gate, a programmable delay circuit coupled to the exclusive OR gate, and an error counter coupled to the exclusive OR gate.

Abstract: A high-speed differential comparator circuit is provided with an accurately adjustable threshold voltage. Differential reference voltage signals are provided to control the threshold voltage of the comparator. The common mode voltage of the reference signals preferably tracks the common mode voltage of the differential high-speed serial data signal being processed by the comparator circuit.

Abstract: A high-speed differential comparator circuit is provided with an accurately adjustable threshold voltage. Differential reference voltage signals are provided to control the threshold voltage of the comparator. The common mode voltage of the reference signals preferably tracks the common mode voltage of the differential high-speed serial data signal being processed by the comparator circuit.

Abstract: An integrated circuit (“IC”) may include circuitry for use in testing a serial data signal. The IC may include circuitry for transmitting the serial data signal with optional jitter, optional noise, and/or controllably variable drive strength. The IC may also include circuitry for receiving the serial data signal and performing a bit error rate (“BER”) analysis in such a signal. The IC may provide output signals indicative of results of its operations. The IC can operate in various modes to perform or at least emulate functions of an oscilloscope, a bit error rate tester, etc., for testing signals and circuitry with respect to jitter-tolerance, noise-tolerance, etc.

Abstract: An IC that includes an eye viewer and a BER checker coupled to the eye viewer, where the BER checker receives a serial data signal from the eye viewer, is provided. In one implementation, the BER checker receives the serial data signal from the eye viewer without the serial data signal passing through a deserializer. In one implementation, the BER checker compares the serial data signal against a reference data signal to determine the BER for the serial data signal. In one implementation, the IC includes an IC core coupled to the eye viewer and the BER checker, where the BER checker is outside the IC core. In one implementation, the BER checker is a dedicated BER checker. In one implementation, the BER checker includes an exclusive OR gate, a programmable delay circuit coupled to the exclusive OR gate, and an error counter coupled to the exclusive OR gate.

Abstract: Methods and apparatus for gathering information about the eye of a high-speed serial data signal include sampling each bit of a repeating, multi-bit data pattern at several eye slice locations. For any given eye slice location, each bit in the data pattern is compared in voltage to a base line reference signal voltage to establish a reference value for that bit. Then the reference signal voltage is gradually increased while the voltage comparisons are repeated until for some bit a result of the comparing is different than the reference value for that bit. This establishes an upper value for the eye at the eye slice location. The reference signal voltage is then gradually decreased to similarly find a lower value for that eye slice.

Abstract: A high-speed differential comparator circuit is provided with an accurately adjustable threshold voltage. Differential reference voltage signals are provided to control the threshold voltage of the comparator. The common mode voltage of the reference signals preferably tracks the common mode voltage of the differential high-speed serial data signal being processed by the comparator circuit.

Abstract: Circuits and a method for tuning an integrated circuit (IC) are disclosed. The IC includes a storage circuit coupled to receive a data signal, a clock input signal and a reset signal. The storage circuit may be used to generate a clock signal. The reset signal is supplied by a reset circuit. The reset circuit may include one or more logic gates to generate the reset signal. The reset circuit receives a phase shifted version of the clock input signal and the reset signal is generated based on the phase shifted version of the clock input signal. In one embodiment, the reset signal is a series of pulses generated at specific intervals to shift the output of the storage circuit from logic high level to logic low level.

Abstract: A phase interpolator circuit includes first and second low pass filter circuits and a multiplier circuit. The first low pass filter circuit increases a common mode voltage of a clock signal to generate a first varying signal. The second low pass filter circuit increases a common mode voltage of a clock signal to generate a second varying signal. The first low pass filter circuit can include a first variable capacitance, and the second low pass filter circuit can include a second variable capacitance. The multiplier circuit has a first input coupled to the first low pass filter circuit and a second input coupled to the second low pass filter circuit. The multiplier circuit generates a third varying signal in response to the first and the second varying signals. The phase interpolator circuit generates a phase shift in the third varying signal.

Abstract: More accurate signal detection circuitry in serial interfaces, particularly on a programmable integrated circuit device, such as a PLD, includes a high-speed, high-resolution, high-bandwidth comparator, along with digital filtering, to reduce the effect of process, temperature or supply variations. The comparator is used to compare a direct input signal with a programmable reference voltage, and, in a preferred embodiment, can detect the signal level within 8 mV accuracy. The output of the comparator may then be digitally filtered. Preferably, both a high-pass digital filter and a low-pass analog filter may be used to eliminate glitches and low-frequency noise. Preferably, the digital filters are programmable to adjust the sensitivity to noise. The filtered output is then latched and output to indicate receipt or loss of signal. This signal detect circuitry can operate reliably at data rates as high as 7 Gbps.

Abstract: A spread spectrum modulation technique uses digital control logic to switch back and forth between two feedback divider ratios so that the PLL spreads output clock frequency between two limits determined by the ratios. The spread spectrum control logic can be integrated into any PLL frequency synthesizer.

Abstract: A spread spectrum modulation technique uses digital control logic to switch back and forth between two feedback divider ratios so that the PLL spreads output clock frequency between two limits determined by the ratios. The spread spectrum control logic can be integrated into any PLL frequency synthesizer.