摘要:
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.
摘要:
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.
摘要:
A storage array including a local clock buffer with programmable timing provides a mechanism for evaluating circuit timing internal to the storage array. The local clock buffer can independently adjust the pulse width of a local clock that controls the wordline and local bitline precharge pulses and the pulse width of a delayed clock that controls the global bitline precharge, evaluate and read data latching. The delay between the local clock and the delayed clock can also be adjusted. By varying the pulse widths of the local and delayed clock signal, along with the inter-clock delay, the timing margins of each cell in the array can be evaluated by reading and writing the cell with varying pulse width and clock delay. The resulting evaluation can be used to evaluate timing margin variation within a die, as well variation from die-to-die and under varying environments, e.g., voltage and temperature variation.
摘要:
A storage array including a local clock buffer with programmable timing provides a mechanism for evaluating circuit timing internal to the storage array. The local clock buffer can independently adjust the pulse width of a local clock that controls the wordline and local bitline precharge pulses and the pulse width of a delayed clock that controls the global bitline precharge, evaulate and read data latching. The delay between the local clock and the delayed clock can also be adjusted. By varying the pulse widths of the local and delayed clock signal, along with the inter-clock delay, the timing margins of each cell in the array can be evaluated by reading and writing the cell with varying pulse width and clock delay. The resulting evaluation can be used to evaluate timing margin variation within a die, as well variation from die-to-die and under varying environments, e.g., voltage and temperature variation.
摘要:
A pulsed ring oscillator circuit for storage cell read timing evaluation provides read strength information. A pulse generator is coupled to a bitline to which the storage cell to be measured is connected. The storage cell thereby forms part of the ring oscillator and the read strength of the storage cell is reflected in the frequency of oscillation. A pulse regeneration circuit is included in the ring so that the storage cell read loading does not cause the oscillation to decay. Alternatively, a counter may be used to count the number of oscillations until the oscillations decay, which also yields a measure of the read strength of the storage cell. The pulse generator may have variable output current, and the current varied to determine a change in current with the storage cell enabled and disabled that produces the same oscillation frequency. The read current is the difference between currents.
摘要:
A delay circuit has a fixed delay path at a lower voltage level, a level converter, and an adjustable delay path at a higher voltage level. The fixed delay path includes an inverter chain, and the adjustable delay path includes serially-connected delay elements selectively connected to the circuit output. In an application for a local clock buffer of a static, random-access memory (SRAM), the lower voltage level is that of the local clock buffer, and the higher voltage level is that of the SRAM. These voltages may vary in response to dynamic voltage scaling, requiring re-calibration of the adjustable delay path. The adjustable delay path may be calibrated by progressively increasing the read access time of the SRAM array until a contemporaneous read operation returns the correct output, or by using a replica SRAM path to simulate variations in delay with changes in voltage supply.
摘要:
A delay circuit has a fixed delay path at a lower voltage level, a level converter, and an adjustable delay path at a higher voltage level. The fixed delay path includes an inverter chain, and the adjustable delay path includes serially-connected delay elements selectively connected to the circuit output. In an application for a local clock buffer of a static, random-access memory (SRAM), the lower voltage level is that of the local clock buffer, and the higher voltage level is that of the SRAM. These voltages may vary in response to dynamic voltage scaling, requiring re-calibration of the adjustable delay path. The adjustable delay path may be calibrated by progressively increasing the read access time of the SRAM array until a contemporaneous read operation returns the correct output, or by using a replica SRAM path to simulate variations in delay with changes in voltage supply.
摘要:
A methor for storage cell read timing evaluation provides read strength information by using a pulsed ring oscillator. A pulse generator is coupled to a bitline to which the storage cell to be measured is connected. The storage cell thereby forms part of the ring oscillator and the read strength of the storage cell is reflected in the frequency of oscillation. A pulse regeneration circuit is included in the ring so that the storage cell read loading does not cause the oscillation to decay. Alternatively, a counter may be used to count the number of oscillations until the oscillations decay, which also yields a measure of the read strength of the storage cell. The pulse generator may have variable output current, and the current varied to determine a change in current with the storage cell enabled and disabled that produces the same oscillation frequency. The read current is the difference between currents.
摘要:
A pulsed ring oscillator circuit for storage cell read timing evaluation provides read strength information. A pulse generator is coupled to a bitline to which the storage cell to be measured is connected. The storage cell thereby forms part of the ring oscillator and the read strength of the storage cell is reflected in the frequency of oscillation. A pulse regeneration circuit is included in the ring so that the storage cell read loading does not cause the oscillation to decay. Alternatively, a counter may be used to count the number of oscillations until the oscillations decay, which also yields a measure of the read strength of the storage cell. The pulse generator may have variable output current, and the current varied to determine a change in current with the storage cell enabled and disabled that produces the same oscillation frequency. The read current is the difference between currents.
摘要:
There is provided a clock distribution network for synchronizing global clock signals within a 3D chip stack having two or more strata. The clock distribution network includes a plurality of clock distribution circuits, each being arranged on a respective one of the two or more strata for providing the global clock signals to various chip locations. Each of the plurality of clock distribution circuits includes a resonant circuit for providing stratum-to-stratum coupling for the clock distribution network. The resonant circuit includes at least one capacitor and at least one inductor.