Abstract: A high voltage charge pump (65) for operation at low power supply voltages includes a plurality of series connected pump stages (66), a predriver logic circuit (68), and two pump driver circuits (70 and 72). The predriver logic circuit (68) receives an external clock signal and provides internal clock signals to the pump driver circuits (70 and 72). The pump driver circuits (70 and 72) provided boosted clock signals to the series connected pump stages (66). The boosted clock signals are provided at a voltage greater than a magnitude of a power supply voltage. By using a boosted clock signal, the charge pump (65) is capable of operating in applications with low power supply voltages, such as 3.3 volts.

Abstract: A nonvolatile random access memory (60) includes a ferroelectric memory array (62). The memory array (62) includes memory cells (86-89 and 91-96) arranged in intersecting rows and columns, where the memory cells (86-89 and 91-96) are coupled to bit lines and word lines. Drive lines are disposed parallel to the bit lines and drive line segments are disposed parallel to the word lines. A drive line segment is coupled to a predetermined number of the memory cells of a row. Coupling transistors (80, 82, 84, and 90) couple a drive line segment to a drive line in response to the word line being selected. The ferroelectric memory array (60) provides the advantage of eliminating a change in the polarization state of non-accessed memory cells connected to a selected drive line, and also provides the advantage of reduced energy consumption.

Abstract: A charge pump with controlled ramp rate (200) includes a charge pump (65), an RC differentiator circuit (258), and a trigger circuit (238). The charge pump (65) receives a clock signal and provides a high output voltage for programming and erasing an EEPROM. The RC differentiator circuit (258) provides a control voltage that is proportional to the ramp-up rate of the high output voltage. The trigger circuit (238) receives the control voltage, and provides a control signal to disable the charge pump (65) if the ramp-up rate exceeds a predetermined rate. When the ramp-up rate falls below the predetermined rate, the trigger circuit (238) provides a control signal to enable the charge pump (65). The trigger circuit (238) has hysteresis to regulate its switching point. Controlling the ramp-up rate of the output voltage reduces the peak tunneling current in the EEPROM cell to increase reliability.

Abstract: A class A amplifier (20) includes an amplifier (21), a capacitor (22), and an output stage (23). The output stage (23) includes a source-follower transistor (24) and a feedback circuit (25). The source-follower transistor (24) receives an analog signal from the amplifier (21) and provides a corresponding output signal to a load. The feedback circuit (25) provides current feedback to maintain a relatively constant drain current in the source-follower transistor (24). The class A amplifier (20) with the feedback circuit (25) provides high current drive capability with low quiescent power consumption, high power supply rejection, high voltage gain, and stable operation without the use of a Miller compensation capacitor.

Abstract: An asymmetric static random access memory cell (50 and 53) includes polysilicon load elements (55 and 56), N-channel pull-down transistors (57 and 58), and N-channel coupling transistors (59 and 60). One of the coupling transistors (59 and 81) has a channel width that is less than the channel width of the other coupling transistor (60 and 80). The asymmetric cells (50 and 53) are located close to power supply voltage terminal V.sub.SS, while conventional symmetrical cells (51 and 52) are located apart from the power supply voltage terminal V.sub.SS. The asymmetric cells (50 and 53) correct an imbalance in the ground path caused by a parasitic resistance (83 and 86) of a diffusion layer (94) that is used to couple the asymmetric cells (50 and 53) to ground potential. The asymmetric cell (50 and 53) improves cell stability without degrading performance or increasing cell area.

Abstract: A self-biased cascode current mirror includes a current mirror (60), and a cascode bias generator (50). The cascode bias generator (50) includes a resistor (51) to provide a bias voltage for the current mirror (60). The current mirror (60) includes cascode transistor (64) and two mirror transistors (62, 63). The bias voltage is approximately equal to a minimum saturation voltage of the cascode transistor (64) plus a gate-source voltage of the transistor (63) of the current mirror (60). The self-biased cascode current mirror (60) has a high output impedance and high voltage swing while providing low power consumption and requiring a small layout area.

Abstract: A flash EEPROM array (22) is erased and a threshold voltage distribution of the erased flash EEPROM cells (36, 39-46) is converged to within a predetermined voltage range by using a two-step erasing procedure. In the first step, flash EEPROM array (22) is electrically bulk erased using a conventional bulk erase procedure. Electrons are tunneled from the floating gate (38) to the source, causing cells (36, 39-46) to have a relatively low threshold voltage. In the second step, the threshold voltage distribution of the array (22) is converged to within the predetermined voltage range by grounding the source and drain of each cell (36, 39-46), while concurrently applying a high positive voltage to the control gate (27) of each cell (36, 39-46). Some electrons are tunneled back to the floating gate (38), thus converging the threshold voltage distribution to within a predetermined range.

Abstract: A memory (80) having a latching BICMOS sense amplifier (20) includes a reduced power data retention mode. The latching BICMOS sense amplifier (20) senses and amplifies differential data signals corresponding to data from a selected memory cell (85). A latch (35) temporarily retains the logic state of the differential data signals in response to a clock signal. The reduced power data retention mode is provided by utilizing selectable current sources (66-75) responsive to an output enable signal. The latching BICMOS sense amplifier (20) allows for very high speed operation, yet provides for reduced power consumption while in a latched state.

Abstract: A memory (20) includes a nonvolatile memory array (32) and a volatile memory array (22). The nonvolatile memory array (32) is subdivided into banks of memory cells. The volatile memory array (22) may also be subdivided into multiple banks, and is smaller than the nonvolatile memory array (32). A transfer circuit (40) transfers the contents of a bank of nonvolatile memory array (32) into a bank of volatile memory array (22) before the data can be accessed by a processor (160). In addition, a preload decision logic circuit (180) may transfer a bank of nonvolatile memory array (32) into volatile memory array (22) invisibly to the processor (160), to have the data available when needed, thus avoiding a space fault. Coupling a smaller volatile memory array (22) to a nonvolatile memory array (32) combines the advantages of faster access times and nonvolatility without greatly increasing the size of the memory (20).

Abstract: An ATD pulse generator circuit (20) provides an ATD pulse at CMOS logic levels in response to a single-ended ECL level input signal transition. An emitter-follower input portion (21), a differential amplifier (23), and emitter-follower portion (25) converts the single-ended input signal to intermediate level differential signals. P-channel transistors (51 and 52) receive the intermediate level differential signals and provide complementary CMOS level outputs signals. Cross-coupled delay portion (29) prevents the N-channel transistors (55 and 56) from switching on until after a delay, causing both of the CMOS level output signals to remain at logic high levels for a predetermined time. Cross-coupling the N-channel transistors (55 and 56) also results in reduced power consumption. A NAND gate (31) receives the logic high levels and provides a CMOS level ATD pulse, the duration of which is adjustable.

Abstract: A direct-path echo cancellation circuit includes a loudspeaker (12), first and second microphones (14, 16), and an in-phase signal cancellation circuit (21, 43). The first and second microphones (14, 16) are positioned adjacent the loudspeaker (12) in order to receive in-phase direct-path echo components (31, 32) of an output signal from the loudspeaker (12). The in-phase signal cancellation circuit (21 or 43) combines the in-phase direct-path echo components of the output signal in order to cancel the direct-path echo components. Direct-path echo cancellation helps to reduce howling and/or oscillation in a full-duplex speakerphone system. Also, direct-path echo cancellation provides more dynamic range to an input signal which is provided to a speakerphone signal processing system (26).

Abstract: A memory (110) having sections of memory cells used ATD to generate the required timing signals, includes ATD generators (189), first summation circuits (180-183), and local summation circuits 185-187. An ATD pulse is generated by the ATD generators (189) when an address signal transitions from one logic state to another. The outputs of the ATD generators (189) are wired-OR connected to input terminals of first summation circuits (180-183). A first summation signal is provided by the first summation circuits (180-183) to each of the local summation circuits (185-187). The local summation circuits (185-187) are positioned in the vicinity of the areas where the timing signals are used. Localized generation of the ATD signals prevents the timing signals for being excessively skewed from each other in different portions of the memory (110).

Abstract: A BICMOS level converter (60) for use at lower power supply voltages includes an input buffer (20) for receiving an ECL level input signal and providing level shifted buffered signals referenced to V.sub.SS, a differential amplifier (61), a clamping circuit (71 and 72) for preventing the bipolar transistors (64 and 65) from operating in saturation, cross-coupled pull-up circuit (67) for a stronger transition from a logic low to a logic high, and a cross-coupled half-latch (75) for reducing the power consumption. The BICMOS level converter (60) has improved switching speeds, wider margins, and reduced power consumption for use at 3.3 volts.

Abstract: An address buffer (20) provides an ATD pulse in response to an address signal transitioning from one logic state to another. The address buffer (20) includes a differential amplifier (22), an emitter-follower transistor (35), and two P-channel transistors (36 and 37). A first current electrode of each of the P-channel transistors is connected to the output nodes (101 and 102) of the differential amplifier (22), and a second current electrode of each of the P-channel transistors (36 and 37) is connected to the base of the emitter-follower transistor (35). Delayed control signals are provided to the gates of the P-channel transistors (36 and 37) by a level converter circuit (60) to cause an ATD pulse to be provided at the emitter of the emitter-follower transistor (35). Generating the ATD pulse in the address buffer allows the ATD pulse to be produced very quickly.

Abstract: A power supply dependent input buffer (20) having a differential amplifier (22), emitter-follower transistors (29 and 32), level shifting resistors (30 and 33), and power supply dependent current sources (31 and 34) receives an ECL input signal referenced to a positive power supply voltage and provides buffered level shifted signals referenced to ground. The current sources (31 and 34) receive a power supply dependent bias voltage that changes in relation to a change in the positive power supply voltage. In turn, the voltage drop across the resistors (30 and 33) changes with respect to the positive power supply voltage such that the buffered level shifted signals are constant with respect to ground. The power supply dependent input buffer (20) is for use at low power supply voltages (such as 3.3 volts), resulting in low power consumption and wider margins on following stages, such as a level converter.

Abstract: A static random access memory (30), resistant to soft error from alpha particle emissions has a high density array of memory cells (44) coupled to word lines (73 and 74) and bit line pairs (68), and operates at low power supply voltages (for example, 3.3 volts). A charging circuit (55) boosts a supply voltage to the memory array above the power supply voltage. The charging circuit (55) includes an oscillator (57), a charge pump (56), and a voltage regulator (58). The boosted supply voltage reduces the effect of an alpha particle hitting the memory array (44) at low power supply voltages. Providing a boosted supply voltage to the memory array (44) improves soft error resistance without adding capacitance to each memory cell (52 and 54).

Abstract: A memory (20) has N.sub.BIAS generators (63 and 73) coupled to the positive and negative power supply lines (61 and 62) at a point close to amplifiers (84 and 85) and address buffers (76) to insure that they all receive the same power supply voltage to prevent an impact on the access times of memory (20). A V.sub.CS generator (65) is located close to power supply bonding pads (23 and 25) and to output buffers (77 and 78) to reduce the effects of power supply line noise on the noise margins. A V.sub.AREF generator provides a reference voltage to the differential amplifiers of address buffers (75 and 76). Locating V.sub.AREF generator (67) close to power supply bonding pads (23 and 25) insures that the reference voltage is always at the midpoint of the input logic swing.

Abstract: A memory (50) having a BICMOS sense amplifier (20) includes a differential amplifier stage (11), emitter-follower input transistors (25 and 26), and emitter-follower output transistors (27 and 28). When sense amplifier (20) is deselected, P-channel transistors (31-37) pull the bases of the bipolar transistors (23-28) to V.sub.DD -2V.sub.BE and P-channel transistors (29 and 30) decouple the bases of emitter-follower output transistors (27 and 28) from the collectors of transistors (23 and 24). At the same time, N-channel transistors (38, 40, 42, 44, and 46) decouple N-channel transistors (39, 41, 43, 45, and 47) from the emitters of bipolar transistors (23-28). Thus, no current can flow, reducing the power consumption of sense amplifier (20). Also, bipolar transistors (23-28) are prevented from being excessively reverse-biased. Additionally, a plurality of sense amplifiers (20) can have their outputs wired-OR connected.

Abstract: A memory (20) for performing read cycles and write cycles has memory cells (30) located at intersections of word lines (32) and bit line pairs (34). A write control circuit (44) receives a write enable signal. The logic state of the write enable signal determines whether memory (20) writes data into, or reads data from, memory (20). Memory (20) includes row address decoding for selecting a word line (32). During a write cycle, a control signal generated by write control circuit (44) and single-sided delay circuit (45) is provided to row predecoder (42). The old row address is latched, and a new address is prevented from selecting a new word line (32) until the write enable signal changes state to begin a read cycle. Controlling word line selection with the write enable signal ensures that bit line equalization occurs before the beginning of a read cycle.

Abstract: A memory (20) has a plurality of columns of memory cells and has a plurality of redundant columns of memory cells. A comparator (45) detects an access to a defective column. A redundant write generator (31) and write fuses (32) are provided for each write portion (30A, 30B, 30C, and 30D) to replace the defective column with a redundant column by replacing a write global data line (37) with a redundant write global data line (39). Redundant read generators (60 and 61) and read fuses (59) are provided for each read portion (50A, 50B, 50C, and 50D) to replace a defective column by deselecting a read global data line (29) and replacing it with a redundant read global data line (44). The fuses and redundant generators are located close to their global data lines, thus reducing the routing of control signals and improving the access time of redundant columns.