Abstract: A non-volatile memory stores both analog and digital information in an array, and has digital and analog read and write circuits and dual I/O interfaces which allow input and output signals in digital or analog form. A user selects the input signal, output signal, and data storage formats. Each selection can be digital or analog format. On-chip analog-to-digital and digital-to-analog converters allow conversion of signals from one format into another. Analog signals can be read or written serially, and one embodiment includes an address counter and an internal oscillator for generating sequential addresses. An output amplifier for driving a speaker and an input amplifier for a microphone allow stored sounds to be directly recorded and reproduced.

Abstract: Circuits and processes write and read analog signals in non-volatile memory cells such as EPROM and flash EPROM cells. One write process applies a control gate voltage which provides a saturation threshold voltage near a target threshold voltage being written. A verify feedback process terminates the write when the target threshold voltage is reached. Variable write pulse widths, voltages, and loadline resistances reduce write time and further improve control of writing. The fast write time of EPROM and flash EPROM cells simplifies control of write processes and therefore reduces chip size and cost in applications such as sound recording. A read process reads a memory cell's threshold voltage using substantially the same circuit as used in the verify feedback process. One read process determines a memory cell's threshold voltage by slowly ramping the control gate voltage and sensing when the cell conducts.

Abstract: Circuits and processes write and read analog signals in non-volatile memory cells such as EPROM and flash EPROM cells. One write circuit to a control gate of a memory cell a voltage which after a long write time would saturate the threshold voltage of the memory cell near a target threshold voltage being written. One such write circuit includes a voltage shifter which generates the voltage to be applied to the control gate of the memory cell from an analog voltage representing a value to be written in the memory cell. A verify feedback circuit terminates the write when the target threshold voltage is reached. The write circuit uses variable write pulse widths, voltages, and loadline resistances to reduce write time and further improve control of writing. The fast write time of EPROM and flash EPROM cells simplifies control of write processes and therefore reduces chip size and cost in applications such as sound recording.

Abstract: An analog memory has comparison logic and a reference voltage generator built on-chip for testing of analog write and read processes. During a test, the reference voltage generator, which may be a resistor tree structure, provides a set of intermediate voltages. One of the intermediate voltages V.sub.IN is written to a selected memory cell. The comparison logic compares other intermediate voltages V.sub.H and V.sub.L to an analog output signal generated by reading the selected memory cell. A digital control signal from an external digital tester selects the levels of voltages V.sub.IN, V.sub.H, and V.sub.L. Typically, voltages V.sub.H and V.sub.L are equal V.sub.IN .+-..DELTA.V where .DELTA.V represents an acceptable resolution for stored analog data. If the signal from reading the selected memory cell falls within a desired range V.sub.IN .+-..DELTA.V, an output digital result signal is set; otherwise, the test result signal is cleared.

Abstract: A non-volatile analog memory contains multiple recording pipelines for sampling and storing values representing an analog signal and/or multiple playback pipelines for playing a recorded signal. Each recording pipeline includes a sample-and-hold circuit and a write circuit coupled to a memory array associated with that pipeline and is capable of write operations that overlap write operations of other recording pipelines. Each playback pipeline includes a read circuit and a sample-and-hold circuit coupled to an associated memory array and is capable of read operations that overlap read operations of other playback pipelines. The pipelines operate sequentially during recording or playback, and the number of pipelines is selected according to a desired sampling frequency. One embodiment provides a modular integrated circuit architecture which allows a user selected number of ICs to be connected together to handle a desired sampling frequency.

Abstract: Circuits and processes write and read analog signals in non-volatile memory cells such as EPROM and flash EPROM cells. One read process determines a memory cell's threshold voltage by slowly ramping the control gate voltage and sensing when the cell conducts. Another read process slowly ramps the source voltage of a memory cell and determines the cell's threshold voltage from the drain voltage of the memory cell. Still another read process connects a cascoding device to a memory cell and biases the memory cell in the linear region while the threshold voltage of the memory cell is determined from a voltage across a load which carries a current that mirrors the current through the memory cell. Read processes disclosed for analog memory cells also apply to binary memory cells, multilevel digital memory cells, and other applications which require precise reading of threshold voltages.

Abstract: In a programmable logic device sense amplifier, switching speed is increased and quiescent power consumption is decreased by incorporating an auxiliary high-speed circuit which assists the sense amplifier to charge the parasitic capacitance of the output node during, and for a short time after, that node's low-to-high voltage transitions. The auxiliary circuit presents a high resistance to the output node at times other than during and shortly after low-to-high transitions, and therefore does not affect the operation of the sense amplifier at these other times. The sense amplifier can be operated in single-ended bit line mode in complementary bit line mode.

Abstract: A programmable macrocell 28 for use in an integrated circuit device including an electronic circuit 32 responsive to control signals and operative to perform particular operations selected by the control signals on input data signals and to develop commensurate output signals, and one or more architecture control circuits 30 each including a programmable EPROM device 34 which when programmed generates a logic signal of a first state and when unprogrammed generates a logic signal of a second state, a read and write control circuit 36 responsive to input program data signals and a corresponding address signal and operative to program the EPROM device 34 by applying a programming potential thereto, and a sensing circuit 38 for sensing the programmed or unprogrammed status of the EPROM device 34 and for developing a commensurate control signal for input to the electronic circuit 32.