Abstract: A logic book for a programmable device such as an application-specific integrated circuit (ASIC) achieves improved radiation tolerance by providing transistors of the same doping type in different well regions that are physically isolated by intervening well regions with complementary doping. For example, n-type field effect transistors (NFETs) may be located in two outer rows of the book with separate Pwell regions, while p-type transistors are located in two inner rows of the book sharing a common Nwell region. Since the NFETs in separate wells are physically isolated from each other, a circuit structure which uses two NFETs in the two outer rows is much less likely to suffer multiple upsets from a single radiation strike. More complicated embodiments of the present invention include additional transistor rows in the stack with isolated Nwells and Pwells.

Abstract: A logic book for a programmable device such as an application-specific integrated circuit (ASIC) achieves improved radiation tolerance by providing notches in an implant well between adjacent transistors and fills the notches with complementary well regions that act as a barrier to charge migration. For example, a row of n-type field effect transistors (NFETs) is located in a Pwell region, while a row of p-type transistors is located in an Nwell region with portions of the Nwell region extending between the NFETs. More complicated embodiments of the present invention include embedded well islands to provide barriers for adjacent transistors in both rows of the book.

Abstract: A scanned value is stored by loading the value into at least three latch stages, generating an output value based on a majority of the latch stage outputs, and feeding the output value back to the inputs of the latch stages to reload the latch stages with the latch circuit output value. Refreshing of the latch stages in this manner repairs any upset latch stage and restores the latch circuit to its original scanned state. The latch circuit may be repeatedly refreshed, preferably on a periodic basis, to prevent failures arising from multiple upsets. The feedback path may include a front-end multiplexer which receives the scan-in line and the output of the majority gate. Control logic selects the output value from the majority gate to pass to the latch stages during the refresh phase. The latch stages may be arranged in a master-slave configuration with a check stage at the slave level. The method is particularly suited for self-correcting scan latches of a microprocessor control system.

Abstract: A latch circuit having three latch stages generates a majority output value from the stages, senses when the latch stage outputs are not all equal, and feeds the majority output value back to inputs of the latch stages to reload the latch stages. The latch circuit uses a not-equal gate whose output is an error signal that can be monitored to determine when a single-event upset has occurred. A master stage is controlled by a first multiplexer which receives one system clock signal, while a slave stage is controlled by a second multiplexer which receives another system clock signal, and the latch stage outputs are connected to respective inputs of the not-equal gate, whose output is connected to second inputs of the multiplexers. The latch circuit is part of a latch control system, and reloading of the latch stages takes less than one cycle of the system clock (less than 500 picoseconds).

Abstract: A method of modeling soft errors in a logic circuit uses two separate current sources inserted at the source and drain of a device to simulate a single event upset (SEU) caused by, e.g., an alpha-particle strike. In an nfet implementation the current flows from the source or drain toward the body of the device. Current waveforms having known amplitudes are injected at the current sources while simulating operation of the logic circuit and the state of the logic circuit is determined from the simulated operation. The amplitudes of the current waveforms can be independently adjusted. The simulator monitors the state of device and makes a log entry when a transition occurs. The process may be repeated for other devices in the logic circuit to provide an overall characterization of the susceptibility of the circuit to soft errors.

Abstract: A dynamic logic circuit apparatus and method for reducing leakage power consumption via separate clock and output stage control reduces power consumption of processors and other systems incorporating dynamic circuits. The power control signal may be a delayed version of the logic clock and turns on the output inverter foot device after the dynamic node has had sufficient time to evaluate, providing a fast evaluate time and reducing leakage through the inverter input when the foot device is off. Alternatively, a coarsely timed static power control signal may be used to control the inverter foot devices. The drains of the inverter foot devices can be commonly connected across multiple circuits, reducing the foot device total area.

Abstract: A dynamic logic circuit incorporating reduced leakage state-retaining devices reduces power consumption of processors and other systems incorporating dynamic circuits. A keeper circuit provides a low leakage retention of the state of the output stage of the dynamic circuit so that an output circuit foot device can be disabled except when required for a transition in the output of the dynamic circuit. The keeper circuit includes a transistor having a smaller area than a corresponding transistor in the output circuit, thus reducing leakage through the gate of the output circuit when the keeper circuit is holding the output and the output circuit foot device is disabled. A self-clocked control of the output circuit foot device can be provided via a delayed version of the dynamic logic gate output, or may be provided by an external control circuit that generates a delayed version of the precharge clock or a multi-cycle signal.

Abstract: A latch circuit having three latch stages generates a majority output value from the stages, senses when the latch stage outputs are not all equal, and feeds the majority output value back to inputs of the latch stages to reload the latch stages. The latch circuit uses a not-equal gate whose output is an error signal that can be monitored to determine when a single-event upset has occurred. A master stage is controlled by a first multiplexer which receives one system clock signal, while a slave stage is controlled by a second multiplexer which receives another system clock signal, and the latch stage outputs are connected to respective inputs of the not-equal gate, whose output is connected to second inputs of the multiplexers. The latch circuit is part of a latch control system, and reloading of the latch stages takes less than one cycle of the system clock (less than 500 picoseconds).

Abstract: A dynamic logic circuit incorporating reduced leakage state-retaining devices reduces power consumption of processors and other systems incorporating dynamic circuits. A keeper circuit provides a low leakage retention of the state of the output stage of the dynamic circuit so that an output circuit foot device can be disabled except when required for a transition in the output of the dynamic circuit. The keeper circuit includes a transistor having a smaller area than a corresponding transistor in the output circuit, thus reducing leakage through the gate of the output circuit when the keeper circuit is holding the output and the output circuit foot device is disabled. A self-clocked control of the output circuit foot device can be provided via a delayed version of the dynamic logic gate output, or may be provided by an external control circuit that generates a delayed version of the precharge clock or a multi-cycle signal.

Abstract: A dynamic logic circuit apparatus and method for reducing leakage power consumption via separate clock and output stage control reduces power consumption of processors and other systems incorporating dynamic circuits. The power control signal may be a delayed version of the logic clock and turns on the output inverter foot device after the dynamic node has had sufficient time to evaluate, providing a fast evaluate time and reducing leakage through the inverter input when the foot device is off. Alternatively, a coarsely timed static power control signal may be used to control the inverter foot devices. The drains of the inverter foot devices can be commonly connected across multiple circuits, reducing the foot device total area.