Motorola Corporation

Freescale Semiconductor,inc.

Lawrence F Childs

Stephen T Flannagan

Ray Chang

Olga R Lu

Kenneth W Jones

Donovan L Raatz

Craig D Gunderson

James David Burnett

Thomas W Liston

Glenn E Starnes

Mark W Jetton

A multi-port memory device having a storage node, a precharge node, a first, second, third, and fourth transistor, and a control module. The first transistor includes a current electrode connected to the storage node, another current electrode connected to a first bit line, and a gate connected to a first wordline. The second transistor includes a current electrode connected to the storage node, another current electrode connected to a second bit line, and a gate connected to a second wordline. The third transistor includes a current electrode connected to the reference node, another current electrode connected to the first bit line, and a gate. The fourth transistor includes a current electrode connected to the precharge node, another current electrode connected to the second bit line, and a gate. The control module deactivates the fourth transistor in response to a dummy access of the first storage module at the second transistor.

Dual port memory device

A memory has an array of memory cells, column logic, a write driver, a voltage detector, and a bootstrap circuit. The array of memory cells is coupled to pairs of bit lines and word lines. The column logic is coupled to the array and is for coupling a selected pair of bit lines to a pair of data lines. The write driver is coupled to the pair of data lines. The voltage detector provides an initiate boost signal when a voltage of a first data line of the pair of data lines drops below a first level during the writing of the pair of data lines by the write driver. The bootstrap circuit reduces the voltage of the first data line in response to the boost enable signal. This is particularly beneficial when the number of memory cells on a bit line can vary significantly as in a compiler.

Memory having self-timed bit line boost circuit and method therefor

A memory having at least one memory array block, the at least one memory array block comprising N wordlines, wherein N is greater than one, is provided. The memory comprises a plurality of sense amplifiers coupled to the at least one memory array block. The memory further comprises at least one dummy bitline, wherein the at least one dummy bitline comprises M dummy bitcells, wherein M is equal to N. The memory further comprises a timing circuit coupled to the at least one dummy bitline, wherein the timing circuit comprises at least one stack of pull-down transistors coupled to a sense circuit for generating a latch control output signal used for timing control of memory accesses. Timing control may include generating a sense trigger signal to enable the plurality of sense amplifiers for read operations and/or generating a local reset signal for terminating memory accesses, such as disabling the plurality of write drivers for write operations.

Memory having a dummy bitline for timing control

A memory circuit has a memory array with a first line of memory cells, a second line of memory cells, a first power supply terminal, a first capacitance structure, a first power supply line coupled to the first line of memory cells; and a second power supply line coupled to the second line of memory cells. For the case where the second line of memory cells is selected for writing, a switching circuit couples the power supply terminal to the first power supply line, decouples the first power supply line from the second line of memory cells, and couples the second power supply line to the first capacitance structure. The result is a reduction in power supply voltage to the selected line of memory cells by charge sharing with the capacitance structure. This provides more margin in the write operation on a cell in the selected line of memory cells.

SRAM having variable power supply and method therefor

A layout portion (20) has a first portion (25), and a second portion (55). In the first portion (25), a reference voltage line (27) is disposed between two V.sub.DD power supply lines (26, 30) for a first predetermined length, for providing capacitive coupling between V.sub.DD and a reference voltage. In the second portion (55), the reference voltage line (27) is disposed between two V.sub.SS power supply lines (28, 41) for a second predetermined length, for providing capacitive coupling between V.sub.SS and the reference voltage. The capacitive coupling stabilizes the reference voltage with respect to the power supply voltage, and reduces power supply noise due to lead inductance and changing current demand. In addition, the power supply lines (26, 28, 30, 41) are disposed half above an N-type region (22) and half above a P-type substrate (21) for reducing local transistor switching noise.

Layout for noise reduction on a reference voltage

A power-on reset circuit (30) for a memory (20) includes a DC model circuit (39), an N.sub.BIAS check circuit (64), and a NAND logic gate (71). A logic low power-on reset signal is provided at power-up of the memory (20) to establish initial conditions in a clock circuit (29) and in row and column predecoders/latches (24, 27). When the power supply voltage, a bandgap reference voltage, and a bias voltage all reach their predetermined voltages, the power-on reset circuit (30) provides a logic high power-on reset signal. In this manner, the power-on reset circuit (30) is assured of providing a logic low power-on reset signal until all of the proper voltage levels are reached. In addition, the power-on reset circuit models a DC circuit equivalent of an address buffer circuit (79) for compensating for process and temperature variations.

Power-on reset circuit for preventing multiple word line selections

A memory (20) includes a write control delay locked loop (52) for controlling a write cycle of the memory (20). The delay locked loop (52) includes an arbiter circuit (264), a voltage controlled delay (VCD) circuit (260), and a VCD control circuit (265). The arbiter circuit (264) compares a clock signal to a delayed clock signal from the VCD circuit (260). In response, the arbiter circuit (264) provides a retard signal to the VCD control circuit (265). The VCD control circuit (265) receives the retard signal and adjusts a propagation delay of the delayed clock signal to compensate for changes in the clock frequency, as well as to compensate for process, temperature, and power supply variations.

Write control for a memory using a delay locked loop

A latching ECL to CMOS input buffer (20) has an input buffer (21) for receiving an ECL input signal, a CMOS latch (35), and driver circuits (55, 65). Transmission gates (31, 32) are used to couple the input buffer (21) to the latch (35) in response to a CMOS clock signal being a logic low. The driver circuits (55, 65) are coupled to transmission gates (31, 32). While the clock signal is a logic low, input nodes of the first and second driver circuits (55, 65) are precharged to a relatively high voltage in order to isolate the input signal from the first and second driver circuits (55, 65). The latch (35) both latches the logic state of the ECL input signal and converts the ECL input signal to CMOS logic levels. This allows an input signal to be latched and level converted within a relatively short period of time.

Latching ECL to CMOS input buffer circuit

A bit line load (380) is coupled to a bit line pair and includes bipolar pull up transistors (389, 403), P-channel load transistors (390, 404), a NAND logic gate (395), and a P-channel equalization transistor. The NAND logic gate (395) senses a differential voltage on the bit line pair, and provides an equalization signal. When a write control signal indicates the end of a write cycle, the equalization signal initiates precharge and equalization of the bit line pair.

Memory having bit line load with automatic bit line precharge and

A synchronous memory (50) having a looped global data line (80) reduces a difference between minimum and maximum propagation delays between different locations in a memory array (51) during a read cycle of the memory (50). The looped global data line (80) has a first portion (80') and a second portion (80'). The first portion (80') extends along an edge of the memory array (51) in a direction substantially parallel to a direction of the word lines of the array (51). Sense amplifiers (73-78) are coupled to the first portion (80') of the looped global data line (80). At one end of the array (51), the second portion (80') of the looped global data line extends back in an opposite direction to the first portion (80') and is coupled to output data circuits (84). Reducing the difference in propagation delays improves noise margins and allows increased operating speed.

Memory having looped global data lines for propagation delay matching

A pipelined memory (20) has a synchronous operating mode and an asynchronous operating mode. The memory (20) includes output registers (34) and output enable registers (48) which are used to electrically switch between the asynchronous operating mode and the synchronous operating mode. In addition, in the synchronous operating mode, the depth of pipelining can be changed between a three stage pipeline and a two stage pipeline. By changing the depth of pipelining, the memory (20) can operate using a greater range of clock frequencies. In addition, the operating frequency can be changed to facilitate testing and debugging of the memory (20).

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Austin, TX, United States of America

Lawrence F Childs