Lattice Semiconductor Corporation

Lallice Semiconductor Corporation

Loren McLaury

Wei Han

Zheng Chen

David Lee Rutledge

Warren Juenemann

Yoshita Yerramilli

Nathan Green

Rohith Sood

Fabiano Fontana

Brad Sharpe-Geisler

David Jennings Wicker

Robert Gary Pollachek

Various techniques are provided to implement power supply regulation for programmable logic devices (PLDs). In one example, a method includes powering configuration memory cells of a PLD with a first voltage. The method further includes configuring the configuration memory cells while the configuration memory cells are powered by the first voltage. The method further includes operating the PLD while the configuration memory cells are powered with a second voltage higher than the first voltage. The method further includes powering the configuration memory cells with a third voltage lower than the first voltage in response to an indication to transition the PLD to a sleep mode of the PLD. Related systems and devices are provided.

Power supply regulation for programmable logic devices

Various techniques are provided to efficiently implement deterministic read back and error detection for programmable logic devices (PLDs). In one example, a PLD includes an array of memory cells arranged in rows and columns, where at least one row includes an enable bit. The PLD further includes an address logic circuit configured to selectively assert the columns of the array by respective address lines. The PLD further includes a register configured to store a value of the enable bit in response to an assertion of an address line corresponding to the enable bit. The PLD further includes a read back circuit configured to selectively provide, for each memory cell, a data bit value stored by the memory cell or a predetermined data bit value based at least on the stored value of the register. Additional systems and related methods are provided.

Deterministic read back and error detection for programmable logic devices

In one memory array embodiment, in order to compensate for bit-line leakage currents by OFF-state bit-cell access devices, a leakage-current reference circuit tracks access-device leakage current over different process, voltage, and temperature (PVT) conditions to generate a leakage-current reference voltage that drives a different leakage-current abatement device connected to each different bit-line to inject currents into the bit-lines to compensate for the corresponding leakage currents. In one implementation, the leakage-current reference circuit has a device that mimics the leakage of each access device configured in a current mirror that drives the resulting leakage-current reference voltage to the different leakage-current abatement devices.

Leakage-current abatement circuitry for memory arrays

A programmable logic device (PLD) is provided with a two-level voltage regulator for powering SRAM cells within the device. In one example, a PLD includes a plurality of static random access memory (SRAM) cells configured to store a configuration for the programmable logic device. The PLD also includes a two-level voltage regulator configured to selectively charge a first power supply node to a reduced voltage and to an enhanced voltage that is greater than the reduced voltage. The SRAM cells are powered through a coupling to the first power supply node. The PLD also includes a control circuit configured to control the two-level voltage regulator to charge the first power supply node to the reduced voltage during a write operation for the SRAM cells and to charge the first power supply node to the enhanced voltage during normal operation of the configured programmable logic device.

SRAM with two-level voltage regulator

In one embodiment, a voltage discharge (VD) system has a slow VD subsystem that provides two concurrent discharge current paths to at least begin to discharge both positive and negative voltages: a first path from the positive-voltage node to ground and a second path from the positive-voltage node to the negative-voltage node. In addition to this relatively slow VD subsystem, the VD system can also have a conventional fast VD subsystem that is turned on after the slow VD subsystem has reduced the positive and negative voltages to some degree (e.g., half of each charge removed). Such a VD system can eliminate dangerous overshoot conditions, even when control-signal skew is present.

Voltage discharge circuit having divided discharge current

A programmable logic device (PLD) is provided that includes: a configuration memory including a plurality of memory cells arranged according to rows and columns, wherein a subset of the rows are RAM rows, and wherein a subset of the columns in each RAM row are RAM columns and at least one column in each RAM row is a flag bit column, the memory cells corresponding to the flag bit column and RAM rows operable to store flag bit signals; a soft error detection (SED) circuit operable to read the configuration memory to derive a checksum; a logic circuit to determine if a RAM row is being read by the SED circuit that includes an asserted flag bit; and a blocking circuit that provides a known logical value to the SED circuit responsive to the logic circuit to block readback of the memory cells corresponding to the RAM rows and RAM columns.

Blocking memory readback in a programmable logic device

Techniques are provided which may be used to reduce power consumed by memory circuits. In one example, a programmable logic device (PLD) includes a plurality of static random access memory (SRAM) cells adapted to configure the PLD for an intended use. A pair of bitlines are connected to the SRAM cells. At least one of the SRAM cells is adapted to provide data signals to the bitlines in response to a wordline signal received by the one of the SRAM cells during a read operation. A sense amplifier is connected to the bitlines and adapted to detect a data value from the data signals in response to a trigger signal received by the sense amplifier during the read operation. Logic is adapted to delay the trigger signal relative to the wordline signal to permit the data signals to settle before the sense amplifier detects the data value.

Triggered sense amplifier

In one embodiment, an integrated circuit includes a flash memory array with at least first and second subarrays, or sectors, of memory cells. The subarrays have a set of shared bitlines and separate sets of word lines. A bitline driver circuit is coupled to the set of shared bitlines, a first row driver circuit is coupled to the set of word lines of the first subarray, and a second row driver circuit is coupled to the set of word lines of the second subarray. The first and second row driver circuits are operable to enable the memory cells of the first subarray to be erased independently of the memory cells of the second subarray. The two row driver circuits are further operable to enable the memory cells of the second subarray to be erased independently of the memory cells of the first subarray.

Flash memory array with independently erasable sectors

In one embodiment of the invention, an integrated circuit such as a programmable logic device includes volatile memory, nonvolatile memory, and a data shift register for reading data from the nonvolatile memory and for reading data from and writing data to the volatile memory. A built in self test (BIST) circuit is operable to test the nonvolatile memory without the data shift register reading data from the nonvolatile memory. The BIST circuit may include a finite state machine for performing at least one of the following tests on the nonvolatile memory: bulk erase, bulk program; margin bulk program; and/or margin bulk erase. A memory controller responsive to the finite state machine is operable to write data to and read data from the nonvolatile memory during testing of the nonvolatile memory.

Programmable logic device with built in self test

Systems and methods are disclosed herein to provide a flash memory array with independently erasable sectors. For example, in accordance with an embodiment of the present invention, an integrated circuit includes a multi-sector flash memory array comprising first and second subarrays of flash memory cells. First and second sets of word lines are connected with control gates of the flash memory cells of the first and second subarrays. A first set of row drivers connected with the first set of word lines are adapted to selectively tri-state or drive the first set of word lines with a first voltage. A second set of row drivers connected with the second set of word lines are adapted to selectively tri-state or drive the second set of word lines with the first voltage. A plurality of bitlines are connected with flash memory cells of the first and second subarrays.

Various techniques are described to test memory arrays of a programmable logic device (PLD). In one example, a PLD includes a first memory array. The PLD also includes a plurality of sense amplifiers adapted to read a plurality of data values stored by the first memory array and provide a plurality of data signals corresponding to the data values. The PLD further includes a test circuit adapted to test the first memory array. The test circuit is coupled with the sense amplifiers and adapted to compare the data signals with a test signal to provide a pass/fail signal. In addition, the PLD includes a second memory array. The PLD also includes a data shift register adapted to test the second memory array.

In one embodiment, an output driver buffer circuit for a logic device includes an output driver transistor adapted to adjust an output voltage of an output pad; a capacitor adapted to be connected to the transistor gate and further adapted when charged and connected to the gate to turn the transistor on; and a reference voltage source adapted to be connected to the transistor gate and further adapted when connected to the gate to maintain the transistor on. The reference voltage source is further adapted to be connected to the transistor gate after the capacitor has turned the transistor on and independent of the level of the output voltage of the output pad.

Low-power output driver buffer circuit

In one embodiment, a memory is provided that includes: a memory cell array adapted to be programmed with a positive voltage from a positive-negative node and to be erased with a negative voltage from the positive-negative node; a negative voltage blocking circuit; and a positive voltage source operable coupled to the negative voltage blocking circuit, the positive voltage source operable to provide the positive voltage to the positive-negative node through the negative voltage blocking circuit, wherein the negative voltage blocking circuit is adapted to prevent the negative voltage from coupling from the positive-negative node to the positive voltage source.

Negative voltage blocking for embedded memories

An integrated circuit includes a first bus and at least one array of embedded memories. Each array includes a second bus such as a bidirectional bus coupled to the embedded memories and to the first bus such that test vectors in the form of data words can be written from the first bus to selected embedded memories in the array. Also included is a built-in-self-test (BIST) circuit operable to compare data words on the first bus to data words read back from the selected embedded memories through the bidirectional bus.

Growing community of inventors

Hillsboro, OR, United States of America

Loren McLaury