International Business Machines Corporation

Andreas Arp

Matthias Ringe

Michael V Koch

Fatih Cilek

Andre Hertwig

Guenther Hutzl

Juergen Koehl

Jeanne P Bickford

Markus Buehler

Christian I Menolfi

Florian Braun

Philipp Salz

Dieter Nissler

Disclosed aspects relate to a clock distribution network of a synchronous logic device. The synchronous logic device has sub-circuits having different clock domains. The clock domains form a hierarchical structure. The clock distribution network has a clock source to provide a global clock signal. A programmable delay line associated with a sub-circuit generates a local clock signal for the sub-circuit by delaying the signal. A global skew control circuit can manage clock skew between the local clock signals. The global skew control circuit may adjust a delay, determine initial operations for the delay lines, verify whether it is possible to perform the initial operations, and perform a correction operation. The correction operation can include correcting the control commands such that the corrected commands lead to the same change of skew adjustment between the local clocks.

Integrated skew control

The present invention provides a system and method of correcting duty cycle (DC) and compensating for active clock edge shift. In an embodiment, the system includes at least one control circuit to receive DCC control signals and to output at least one first adjustment signal, at least one second adjustment signal, at least one first correction signal, and at least one second correction signal, at least one adjustment circuit to change a DC value of an input clock signal, at least one correction circuit to compensate for a shift of an active clock edge of the input clock signal, and where one of the at least one adjustment circuit and the at least one correction circuit is to receive the input clock signal and wherein one of the at least one adjustment circuit and the at least one correction circuit is to transmit a corrected output clock signal.

Correcting duty cycle and compensating for active clock edge shift

Disclosed aspects relate to a clock distribution network of a synchronous logic device. The synchronous logic device comprises multiple sub-circuits belonging to different clock domains. The clock distribution network comprises a clock source operable for providing a global clock signal, at least one programmable delay line associated with a certain sub-circuit operable for generating a local clock signal for said sub-circuit by delaying the global clock signal or a signal derived therefrom and a global skew control circuit for managing clock skew between the local clock signals. The global skew control circuit is operable for managing clock skew between at least some local clock signals by regularly adjusting the delay caused by at least one programmable delay line when in a deskewing operating mode, and disabling adjusting the delays of the programmable delay lines when in a locked operating mode.

Skew control

An apparatus of performing a clock skew adjustment between N clock signals. 2(N&#x2212;1) skew sensors are configured as successive pairs k, each pair k having a first skew sensor and a second skew sensor. The first skew sensor receives a third clock signal obtained by delaying the first clock signal by a first delay and a fourth clock signal obtained by delaying the second clock signal by a second delay, and generates first information based on the third and fourth clock signals. The second skew sensor receives a fifth clock signal obtained by delaying the first clock signal by a third delay and a sixth clock signal obtained by delaying the second clock signal by a fourth delay, and generates second information based on the fifth and sixth clock signals. A skew controller performs the clock skew adjustment based on the first and second information.

Method and apparatus for clock skew control with low jitter in an integrated circuit

An apparatus of performing a clock skew adjustment between at least first and second clock signals includes first and second skew sensors and a skew controller. The first skew sensor receives a third clock signal obtained by delaying the first clock signal by a first delay and a fourth clock signal obtained by delaying the second clock signal by a second delay, and generates first information based on the third and fourth clock signals. The second skew sensor receives a fifth clock signal obtained by delaying the first clock signal by a third delay and a sixth clock signal obtained by delaying the second clock signal by a fourth delay, and generates second information based on the fifth and sixth clock signals. Each of the first and second information varies depending on the clock skew. The skew controller performs the clock skew adjustment based on the first and second information.

A circuit for measuring a transition time of a digital signal may be provided. The circuit comprises a window detector comprising a comparator circuitry arranged for generating a first signal based on comparing said digital signal with a first reference voltage and for generating a second signal based on comparing said digital signal with a second reference voltage. Additionally, the circuit comprises a time-difference-to-digital converter operable for converting a delay between an edge of said first signal and an edge of said second signal into a digital value, said digital value characterizing said transition time of said digital signal.

On-chip waveform measurement

Reducing dynamic clock skew and/or slew in an electronic circuit is provided by: referencing a layout database and/or netlist of a design for the electronic circuit; identifying a set of neighboring buffer pairs with active buffers and adjacent sub-meshes, which are connected by a shorting bar; for each neighboring buffer pair of the set: placing a dummy buffer for each of their active buffers in the adjacent sub-meshes close to the active buffers; routing an input of a first dummy buffer located in a first sub-mesh to an output of an active buffer in a second sub-mesh; routing an input of a second dummy buffer located in the second sub-mesh to an output of an active buffer in the first sub-mesh; and connecting inputs of the first and second dummy buffers to the shorting bar.

Reducing dynamic clock skew and/or slew in an electronic circuit

The present disclosure regards adjusting a duty cycle, which includes generating a duty cycle signal having a voltage representing a duty cycle of a clock signal; adjusting a reference voltage generated by an adjustable reference voltage generator to match the duty cycle signal to produce a first matched value; inverting voltage sources of the reference voltage generator; adjusting, while the voltage sources are inverted, the reference voltage to produce a second matched value; and calculating a duty cycle value based on the first and second matched values.

Duty cycle adjustment with error resiliency

A method for detecting rising and falling transitions of internal signals of an array or integrated circuit. An apparatus used in the method comprises a delay line with a plurality of first to Nth delay elements, latches, and first to Nth groups of logic gates. Each of the first to Nth groups of the logical gates includes an AND gate and a NOR gate. The method determines rising and falling signals based on output signals of the logic gates in the apparatus; in odd numbered groups of the logic gates, the AND gate detects the rising transition and the NOR gate detects the falling transition; in even numbered groups of the logic gates, the AND gate detects the falling transition and the NOR gate detects the rising transition.

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Nufringen, Germany

Andreas Arp