Abstract: A level detection circuit for monitoring the level of a power supply voltage and producing an output signal at power on for resetting various system elements powered by the supply voltage when the supply voltage reaches a predetermined level. The detection circuit, which is powered by the supply voltage includes a voltage reference circuit which produces a reference voltage having a magnitude which is relatively independent of the power supply voltage. A translator circuit functions to produce a translated voltage indicative of the supply voltage magnitude and which is comparable in magnitude to the reference voltage when the supply voltage is at a suitable level such that the system will accept a power on reset pulse. A comparator circuit functions to compare the reference voltage with the translated voltage and cause an associated output circuit to issue the reset pulse. The reset circuit typically includes a one shot circuit, the output of which is logically ORed with the amplified comparator output.

Abstract: A method for verifying the status of selected nonvolatile memory cells of an integrated memory circuit, such as during a memory erase or programming operation, and an integrated nonvolatile memory circuit including circuitry for performing this verification method. Preferably, the invention employs simple logic circuitry including a flip-flop to assert successful verification data only in response to a continuous validity of a verification signal throughout a sampling period, thereby avoiding false assertion of successful verification data. The sampling period is preferably longer than the expected duration of fluctuations due to noise in the verification signal. During the sampling period of a verification operation, the logic circuitry receives a raw verification signal indicative of the instantaneous relation between a measured threshold voltage of a selected memory cell and a reference voltage.

Abstract: To provide a boundaryless burst mode access, a memory array is divided into two or more subarrays. Each subarray has its own row and column decoders. The columns of each subarray are divided into groups. A sense amplifier circuit is provided for each group of columns. The column decoder of each subarray selects simultaneously one column from each group so that the memory locations in one row in the selected columns have consecutive addresses. The memory locations in the selected row and columns are read by the sense amplifier circuits. While the contents of the sense amplifier circuits of one subarray are transferred one by one to the memory output, consecutive memory locations of another subarray are read to the sense amplifier circuits. In some embodiments, to save power, sense amplifier circuits are disabled when their outputs are not transferred to the memory output.

Abstract: An apparatus and method for improving the reliability of floating gate transistors used in memory cell applications by controlling the electric field induced across the tunnel oxide region of the floating gate transistor when discharging electrons from floating gate is provided. The invention comprises method and apparatus for varying the resistance applied to the drain electrode of the floating gate device and/or varying the voltage applied to the source electrode of the floating gate device to control the electric field in the tunnel oxide region of the floating gate device. In the preferred embodiment of the invention utilized in an EEPROM memory cell, both a method and an apparatus applying a variable resistance and a method and an apparatus applying a variable voltage are utilized simultaneously. The method and apparatus provide an optimal electric field intensity to control electron tunneling in the tunnel region of the floating gate device during discharge of electrons from the floating gate.

Abstract: A non-volatile memory apparatus having a plurality of memory cells, each memory cell including a floating gate tunnel device (130) having a drain (134) and a floating gate read transistor (140) having a source (142) and a drain (144), the tunnel device and read transistor in each respective cell having a common floating gate (138, 148) and a common control gate (136, 146).

Abstract: A four device cell for an electrically erasable programmable logic device includes a floating gate tunnel device (sometimes referred to as a tunnel capacitor), a floating gate read transistor having its floating gate and control gate connected respectively to the floating gate and control gate of the tunnel capacitor, a read select transistor for selectively coupling the drain of the floating gate read transistor to a product term output in response to an input term, and a write select transistor for selectively coupling the drain of the floating gate tunnel capacitor to a write data line in response to the signal on a write select line. During sensing, the control gates of all the floating gate tunnel capacitors are kept at a constant voltage V.sub.cg. The drains of all of the floating gate tunnel capacitors are also kept at a constant voltage V.sub.WDL chosen to minimize read disturb on the tunnel capacitor. Preferably V.sub.WDL =V.sub.cg. V.sub.

Abstract: A four device cell is disclosed for an electrically erasable programmable logic device. The four devices include a floating gate tunnel capacitor, a floating gate read transistor having its floating gate and control gate connected respectively to the floating gate and control gate of the tunnel capacitor, a read select transistor for selectively coupling the drain of the floating gate read transistor to a product term output in response to an input term, and a write select transistor for selectively coupling the drain of the floating gate tunnel capacitor to a write data line in response to the signal on a write select line. During sensing, the control gates of all the floating gate tunnel capacitors are kept at a constant voltage V.sub.cg. The drains of all of the floating gate tunnel capacitors are also kept at a constant voltage V.sub.WDL chosen to minimize read disturb on the tunnel capacitor. Preferably V.sub.WDL =V.sub.cg .multidot.V.sub.

Abstract: A temperature compensated complementary metal-insulator-semiconductor oscillator receives a temperature independent reference voltage from an external source. The temperature independent reference voltage is attenuated and summed with a threshold voltage in order to bias a gate electrode of MOSFET. A bipolar p-n junction diode is connected to the MOSFET at a source electrode in order to bias the MOSFET with a temperature dependent forward voltage drop to compensate for temperature variations therein. The MOSFET controls a temperature independent current. A current mirror assembly receives the current and controls a Schmitt trigger oscillator. The Schmitt trigger oscillator generates a signal having a temperature independent constant period.

Abstract: In an electronic circuit having a reference voltage generator, a device is provided to stabilize the reference voltage against operating temperature variations. Temperature insensitivity is achieved by interposing a source follower type circuit, having a fuse programmable variable resistance feedback loop, between the generator and the circuitry using the reference voltage level. The present invention is particularly suitable for integrated circuits which employs a single reference potential generating circuit device.