Abstract: A digital frequency multiplier circuit is disclosed. The digital frequency multiplier circuit includes a digitally controlled oscillator (DCO), a phase detector and a control circuit. The DCO generates an internal feedback signal. The phase detector detects a phase difference between the internal feedback signal and an external reference clock signal. Coupled between the phase detector and the DCO, the control circuit adjusts the DCO to align the internal feedback signal with the external reference clock signal after a phase difference between the internal feedback signal and the external reference clock signal has been detected. The control circuit also locks a modulation frequency of the DCO and monitors the state of the digital frequency multiplier circuit in order to maintain the lock.

Abstract: Power-gated circuitry is put in a “sleep mode” that selectively gates both the power supply rails for static power control and the clock distribution for dynamic power control. A time interval M is established following a wake-up signal that includes the time to power-up, perform a computation, and return a result to the following circuitry. Likewise, a time interval N is established that indicates how long to wait after a result is returned before the power-gated circuitry is returned to the sleep mode to assure a desired performance. When a power-gated circuit is going to be needed for a future computation, it is issued a wake-up signal and a predetermined estimated time K for receipt of a next wake-up signal. A decision is made by analyzing the times M, N, and K as to when to return a power-gated circuit to the sleep mode following activation by a wake-up signal.

Abstract: A wordline-to-bitline timing ring oscillator circuit for evaluating storage cell access time provides data on internal bitline access timing, and in particular the total wordline select-to-bitline read output timing. Columns of a storage array are connected in a ring, forming a ring oscillator. The bitline read circuit output of each column is connected to a wordline select input of a next column, with a net inversion around the ring, so that a ring oscillator is formed. The period of oscillation of the ring oscillator is determined by the total wordline select-to-bitline read circuit output timing for a first phase and the pre-charge interval time for the other phase, with the bitline read timing dominating. The circuit may be applied both to small-signal storage arrays, with the sense amplifier timing included within the ring oscillator period, or to large-signal storage arrays, with the read evaluate circuit timing included.

Abstract: In an exemplary embodiment of the present invention, a local clock buffer (LCB) fabricated in a semiconductor receives a global clock signal as input. The LCB implements a pulse width controller that is operationally coupled to the LCB and an output driver forming a ring oscillator. The output driver outputs a pulse width adjusted signal. The pulse width of the pulse width adjusted signal is adjustable by way of the pulse width controller and is related in frequency to the global clock signal. A second ring oscillator (also referred to as the nclk loop) can also be implemented to server as the global clock signal. The pulse width controller can be used to precisely adjust the pulse width of the pulse width adjusted signal. A pulse width multiplier can be implemented to allow direct observation and measurement of the pulse width of the pulse width adjusted signal.

Abstract: A digital frequency multiplier circuit is disclosed. The digital frequency multiplier circuit includes a digitally controlled oscillator (DCO), a phase detector and a control circuit. The DCO generates an internal feedback signal. The phase detector detects a phase difference between the internal feedback signal and an external reference clock signal. Coupled between the phase detector and the DCO, the control circuit adjusts the DCO to align the internal feedback signal with the external reference clock signal after a phase difference between the internal feedback signal and the external reference clock signal has been detected. The control circuit also locks a modulation frequency of the DCO and monitors the state of the digital frequency multiplier circuit in order to maintain the lock.

Abstract: A high performance, low power up/down counter is set forth. The counter presented is controlled by two clock pulses, an up pulse and a down pulse, and updates all bits of the counter in parallel. These bits are then latched using a scannable pulsed limited output switching dynamic logic latch. By using a limited switch dynamic logic latch, the counter is able to utilize the speed of dynamic logic without requiring the traditional dynamic logic power. The area saved and speed gained by using a dynamic latch is significant compared to a typical edge-triggered flip-flop. Additionally, by computing all the next count state bits in parallel, the counter reduces an overall count computation delay by eliminating the counter ripple.

Abstract: A phase detector which provides a dynamic output signal and which automatically resets if a reference clock signal and a feedback clock signal align after an output pulse is generated. With the phase detector in accordance with the present invention, when there is a difference between the positive clock edges of the reference clock signal and the feedback clock signal, the phase detector generates output pulse. The output is used to correct the feedback clock signal. In the next cycle, if the feedback signal is corrected so that both the reference clock signal and feedback clock signal are aligned, then the output signals are reset to zero. The ability to reset advantageously prevents an unexpected correction that can occur in certain phase detector designs.

Abstract: A cascaded pass-gate test circuit including interposed split-output drive devices provides accurate measurement of critical timing parameters of pass gates. The rise time and fall time of signals passed through the pass gate can be separately measured in a ring oscillator or one-shot delay line configuration. Inverters or other buffer circuits are provided as drive devices to couple the pass gates in cascade. The final complementary tree in each drive device is split so that the only one of the output pull-down transistor or pull-up transistor is connected to the next pass gate input, while the other transistor is connected to the output of the pass gate. The result is that the state transition associated with the device connected to the pass gate input is dominant in the delay, while the other state transition is propagated directly to the output of the pass gate, bypassing the pass gate.

Abstract: A test structure for characterizing a production static random access memory (SRAM) array. The test structure includes a characterization circuit having multiple memory cell columns connected in series to form a ring configuration. The characterization circuit is fabricated on a wafer substrate in common with and proximate to a production SRAM array. The characterization circuit preferably includes SRAM cells having a circuit topology substantially identical to the circuit topology of memory cells within the production SRAM array. In one embodiment, the test structure is utilized for characterizing a multi-port memory array and includes multiple memory cell columns connected in series to form a ring oscillator characterization circuit. Each cell column in the characterization circuit includes multiple SRAM cells each having a latching node and multiple data path access nodes.

Abstract: A system and method for implementing arithmetic logic unit (ALU) support for value-based control dependence sequences. According to a first embodiment of the present invention, an ALU generates a carry-out signal designating one of a first and second value as a larger value. In response to the carry-out signal, the ALU updates a storage location with a third value, which is the larger value. According to a second embodiment of the present invention, an ALU generates a carry-out signal designating one of a first and second value as a larger value. In response to the carry-out signal, the ALU updates a storage location with a third value. The third value is a fourth value, if the carry-out signal designates the first value as the larger value or the third value is a fifth value, if the carry-out signal designates the second value as the larger value.

Abstract: The present invention relates to a methodology for controlling the power consumption in a computing device based upon extended register file extension values, the method further comprising the steps of identifying an upper bit data register value and a lower bit data register value for a data register value, and inputting the upper bit data register value to a detect logic component, wherein the upper bit data register value is used to generate a data register extension value. The method further comprises the steps of utilizing the data register extension value as a power control signal serving to activate or deactivate a power supply signal to a segment of a data path, and updating the data register extension value in a subsequent data register write computational function.

Abstract: A dynamic logic gate has a dynamic node pre-charged in response to a pre-charge phase of a clock signal and a logic tree with a plurality of logic inputs for evaluating the dynamic node during an evaluate phase of the clock signal in response to a Boolean combination of the logic inputs. The dynamic node is coupled to an output with an inverting logic circuit. A hybrid keeper circuit, coupled to the dynamic node, uses a parallel NFET and a first PFET to produce the same current as a larger PFET when operated with a high voltage power supply. The common node of the combination is coupled to the dynamic node by second PFET larger than the first PFET in one embodiment. At high voltage, the hybrid keeper provides a strong keeper current when potential noise is highest. The hybrid keeper current is automatically reduced at low voltage allowing performance to be maintained while keeping the effective noise immunity of the high voltage operation.

Abstract: An in-circuit timing monitor having a selectable-path ring oscillator circuit provides delay and performance measurements in an actual circuit environment. A test mode signal is applied to a digital circuit to de-select a given functional input signal applied to a functional logic block within the digital circuit and replace it with feedback coupled from an output of the functional logic block, when test mode operation is selected. The signal path from the de-selected input to the output is selected so that the signal path will oscillate, and a characteristic frequency or phase of the output signal is measured to determine the delay. Other inputs to the functional logic block are set to a predetermined set of logic values. The selection may be made at a register preceding the digital inputs or made in the first level of logic of the functional logic block.

Abstract: A scannable latch incorporates a logic front end that has at least one dynamic logic gate that has a logic tree that perform the normal Boolean logic operation. The dynamic logic gate is combined a scan pull-down logic tree that is coupled to a scan hold latch output and to the dynamic node of the dynamic logic gate. A scan clock and a normal clock determine whether the logic circuitry is in the normal logic mode or in the scan test mode. A static output latch has at least one input that is responsive logic state of a dynamic node. The evaluated state of the dynamic node is set by either the logic tree of the dynamic logic gate or the scan pull-down logic tree of the scan circuitry in response to the logic state of the scan clock or the normal clock.

Abstract: A scannable latch incorporates a logic front end that has at least one dynamic logic gate that has a logic tree that perform the normal Boolean logic operation. The dynamic logic gate is combined a scan pull-down logic tree that is coupled to a scan hold latch output and to the dynamic node of the dynamic logic gate. A scan clock and a normal clock determine whether the logic circuitry is in the normal logic mode or in the scan test mode. A static output latch has at least one input that is responsive logic state of a dynamic node. The evaluated state of the dynamic node is set by either the logic tree of the dynamic logic gate or the scan pull-down logic tree of the scan circuitry in response to the logic state of the scan clock or the normal clock.

Abstract: A programmable clock generator circuit receives control signals and a global clock and generates a pulsed data clock and a scan clock in response to gating signals. The clock generator has data clock and scan clock feed-forward paths and a single feedback path. Delay control signals program delay elements in the feedback path and logic gates reshape and generate a feedback clock signal. The global clock and the feedback clock signal are combined to generates a pulsed local clock signal. A scan clock feed-forward circuit receives the local clock and generates the scan clock. A data clock feed-forward circuit receives the local clock and generates the data clock with a logic controlled delay relative to the local clock signal. The feedback clock is generated with controlled delay thereby modifying the pulse width of the data and scan clocks independent of the controlled delay of the data clock feed-forward path.

Abstract: In an exemplary embodiment of the present invention, a local clock buffer (LCB) fabricated in a semiconductor receives a global clock signal as input. The LCB implements a pulse width controller that is operationally coupled to the LCB and an output driver forming a ring oscillator. The output driver outputs a pulse width adjusted signal. The pulse width of the pulse width adjusted signal is adjustable by way of the pulse width controller and is related in frequency to the global clock signal. A second ring oscillator (also referred to as the nclk loop) can also be implemented to server as the global clock signal. The pulse width controller can be used to precisely adjust the pulse width of the pulse width adjusted signal. A pulse width multiplier can be implemented to allow direct observation and measurement of the pulse width of the pulse width adjusted signal.

Abstract: A cascaded pass-gate test circuit including interposed split-output drive devices provides accurate measurement of critical timing parameters of pass gates. The rise time and fall time of signals passed through the pass gate can be separately measured in a ring oscillator or one-shot delay line configuration. Inverters or other buffer circuits are provided as drive devices to couple the pass gates in cascade. The final complementary tree in each drive device is split so that the only one of the output pull-down transistor or pull-up transistor is connected to the next pass gate input, while the other transistor is connected to the output of the pass gate. The result is that the state transition associated with the device connected to the pass gate input is dominant in the delay, while the other state transition is propagated directly to the output of the pass gate, bypassing the pass gate.

Abstract: A dynamic logic gate has an asymmetrical dual-gate PFET device for charging a dynamic node during a pre-charge phase of a clock. A logic tree evaluates the dynamic node during an evaluate phase of the clock. The front gate of the asymmetrical dual-gate PFET device is coupled to the clock signal and the back gate is coupled to the ground potential of the power supply. When the clock is a logic zero both the front gate and the back gate are biased ON and the dynamic node charges with maximum current. The clock signal transitions to a logic one during the evaluation phase of the clock turning OFF the front gate. The back gate remains ON and the asymmetrical dual-gate PFET device operates as a keeper device with a current level sufficient to counter leakage on the dynamic node.

Abstract: A method and apparatus for fail-safe and restartable system clock generation provides recovery from failures due to incorrect clock generator settings or from marginal clock distribution components. Clock failure is detected at a point along the clock distribution path between the output of the clock generator and the downstream circuits. If a clock failure is detected, a second clock, which may be the clock generator reference clock, is used to operate the downstream circuits. The clock generator, which may be a phase-lock loop, is then restarted, either with a predetermined loop filter voltage at which downstream circuits are guaranteed to operate, or with a divider setting on the output of the clock generator that reduces the frequency so that downstream circuits are guaranteed to operate. Parameters of the clock generator can thereby be reset and operating conditions determined before restoring the output of the clock generator to the downstream circuits.