Macronix International Co., Ltd.

Yin-Shang Liu

Chun-Hsiung Hung

Kuen-Long Chang

Ray-Lin Wan

Weitong Chuang

Ken-Hui Chen

I-Long Lee

Yao-Wu Cheng

Yu-Ming Hsu

Y T Lin

Hao-Hsiung Yang

A sensing circuit for sensing the logic state of a memory cell which minimizes read times is described which includes a first circuit branch corresponding to an array circuit path and a second circuit branch corresponding to a reference cell circuit path. In operation during the pre-decode interval, additional load and current generation circuitry are enabled in the first circuit path so that the voltage as seen by the sensing input of a sensing circuit comparator is driven to be essentially equivalent to that of the reference signal as established by the reference cell circuit path on the reference input of the sensing circuit comparator. Once the address has been decoded, the additional load circuitry is disabled so as to allow the sensing input of the comparator to transition to a voltage representative of the logic state stored in the memory cell.

Memory cell sense amplifier

A page mode flash memory or floating gate memory device, including a page buffer based upon low current bit latches, and additional capabilities for parallel read and parallel program verify operations. The present device includes bit latch circuitry and/or method steps that facilitate such parallel operations and avoid data conflicts. Circuitry for separate read signals can serve to isolate the operations. Additionally, circuitry tied to the data verification signal can also be used. A diode type device can be used to isolate signal conditions that might indicate the cell does not need to be programmed. Bit-by-bit precharging of the bit lines can also be employed in order to save precharging power. Additionally, the large capacitance of the dataline might be used to delay discharging a particular dataline, and thereby allow a latch enabling signal to go high, thus eliminating the need for further isolation circuitry, or the like.

Parallel read and verify for floating gate memory device

A technique for regulating a negative voltage charge pump to induce Fowler-Nordheim tunneling in floating gate cells controls applied bias to compensate for variations in the supply potential VDD, temperature, and the gate coupling ratio (GCR) or other characteristics of the memory cells which depend on manufacturing processes. A supply circuit for a negative voltage includes a voltage regulator that is coupled to the negative voltage source to maintain the negative voltage at a regulated level. The regulator includes an element that establishes the regulated level according to the manufacturing processes and temperature of the device. The regulator also comprises a circuit which establishes the regulated level in response to the supply voltage. Thus, where the negative voltage generator is utilized in a floating gate memory device, the element that establishes the regulated level according to manufactured processes and temperatures comprises a floating gate transistor manufactured according to the same processes as the non-volatile memory cells in the array on the device.

Regulated negative voltage supply circuit for floating gate memory

Write protected, non-volatile memory device with user programmable

An embodiment of the invention provides a buffer circuit having reduced power consumption. The buffer circuit comprises a power saving switch coupled to a buffer at a bias node. The buffer has an input that is adapted to receive input voltages at TTL levels, for example, and has an output adapted to provide output voltages at CMOS levels, for example. The power saving switch includes a level shifter and a voltage control circuit both coupled to the bias node. The output voltage of the buffer is fed back to the power saving switch. When the output voltage is at a low CMOS level, the power saving switch uses the voltage control circuit to provide a first bias voltage to the bias node. When the output voltage is at a high CMOS level, the power saving switch uses the level shifter to provide a second bias voltage to the bias node. The second bias voltage is chosen such that it prevents current flow between the bias node and the buffer at a predetermined input cutoff voltage. The level shifter provides a relatively constant second bias voltage by providing a relatively constant voltage shift V.sub.LS between a level shifter reference voltage V.sub.ref and the bias node. In the present embodiment, this voltage shift V.sub.LS is the absolute value of the gate to source threshold voltage of a FET. Accordingly, the second bias voltage is V.sub.ref -V.sub.LS. In one embodiment, the voltage control circuit includes a second level shifter to provide the first bias voltage.

Power saving buffer circuit buffer bias voltages

The present invention provides a new (ATD) address transition detection circuit for use on an address bus having any number of address lines. An ATD circuit is disclosed which comprises a first and second circuit and an interval timer. The first circuit has a first and second input and an output. The first circuit receives, at the first input, a change signal corresponding to transitions in one or more addresses of an address bus. In response, the output of the first circuit transitions from an initial first state to a second state. The first circuit is also responsive to a reset command at the second input to return the output to the first state. The interval timer has an output coupled to the second input of the first circuit and an input. The interval timer responsive to an initialize command at the input initiates a timed interval and after the timed interval generates the reset command at the output. The second circuit has an output coupled to the input of the interval timer and an input. The second circuit responsive to the change signal at the input generates an initialize command at the output. The circuit provides a second state at the output of the first circuit, for all including the last received in a series of change signals. This assures that all address transitions have been detected before a memory access is allowed.

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Tsao-Twen, Taiwan

Yin-Shang Liu