Abstract: Methods and apparatus for achieving analog storage in a non-volatile memory array. The array consists of memory cells that utilize Fowler-Nordheim tunneling for erasure and hot electron injection for programming. Writing into a cell is performed by an initial erasure followed by a controlled sequence of program operations during which the cell is programmed in small increments. The stored voltage is read after each program step and when the voltage read back from the cell is equal or just beyond the desired analog level, the sequence of program steps is terminated. The read condition for the cell applies a positive voltage to the drain or common line and a positive voltage to the control gate. The source is connected through a load device to a negative (ground) supply. The output from the cell is the actual voltage that exists at the source node. There is no current sensing or comparison with a reference voltage to determine the output state.

Abstract: Methods and apparatus for achieving analog storage in a non-volatile memory array. The array consists of memory cells that utilize Fowler-Nordheim tunneling for erasure and hot electron injection for programming. Writing into a cell is performed by an initial erasure followed by a controlled sequence of program operations during which the cell is programmed in small increments. The stored voltage is read after each program step and when the voltage read back from the cell is equal or just beyond the desired analog level, the sequence of program steps is terminated. The read condition for the cell applies a positive voltage to the drain or common line and a positive voltage to the control gate. The source is connected through a load device to a negative (ground) supply. The output from the cell is the actual voltage that exists at the source node. There is no current sensing or comparison with a reference voltage to determine the output state.

Abstract: An integrated circuit which operates to store an input analog signal within an analog storage device such as an EEPROM is disclosed. Initially, a target voltage is determined for applying to the memory cell with the target voltage set to about 90% of the input analog signal voltage. A high voltage ramp is applied to the memory cell to set the voltage of the memory cell to the target voltage. A read operation is simultaneously performed while the high voltage ramp is applied to detect the voltage stored on the cell and to terminate the application of the high voltage ramp once the target voltage is reached. Thereafter, a normal read operation is performed on the memory cell to detect the actual voltage of the cell. A new target voltage is determined based upon the actual voltage of the memory cell and the input analog signal voltage. The high voltage ramp is again connected to the memory cell to set the cell to the new target voltage while a simultaneous read operation is performed.

Abstract: In a double-sided pulse width modulator, an amplifier has a first input connected to a first reference potential, a second input, and an output. A first bank of storage elements have a first terminal connected to the second input of the amplifier, and a second terminal. A first bank of switches have an output terminal connected to a second terminal of the storage elements, an input terminal, and a control terminal connectable by a timing gate to an output of the modulator and a polarity control bit for a first value to be input into the input terminals. A feedback storage element is connected in parallel with a first timing switch between the second input of the amplifier and the output of the amplifier. A comparator has a first input connected to a second reference potential, a second input, a timing enable input, and an output. A second bank of storage elements have a first terminal connected to the second input of the comparator, and a second terminal.

Abstract: This invention utilizes the small cell size of the NAND storage cell structure in an analog storage and playback device. This is achieved, in part, by using a special, zero current storage cell, in which in the read mode, the cell loading current is waveshaped to attain an optimal dynamic range and to avoid the resistive effects of series parasitic resistances of other transistors in the source node or drain node, and to avoid the transistor conductance variations of all the transistors in the read path. The loading current is waveshaped to reduce possible overshoot and settling effects to achieve the fine output voltage resolution in an optimal sensing time. Details of the method and alternate embodiments are disclosed.

Abstract: This invention utilizes the small cell size of the NAND storage cell structure in an analog storage and playback device. This is achieved, in part, by using a special, zero current storage cell, in which in the read mode, the cell loading current is waveshaped to attain an optimal dynamic range and to avoid the resistive effects of series parasitic resistances of other transistors in the source node or drain node, and to avoid the transistor conductance variations of all the transistors in the read path. The loading current is waveshaped to reduce possible overshoot and settling effects to achieve the fine output voltage resolution in an optimal sensing time. Details of the method and alternate embodiments are disclosed.

Abstract: The present invention is an apparatus for storing a voltage level within a storage element such as an EEPROM. The apparatus includes a track and hold circuit that receives the voltage level to be stored and an integrator that determines a target voltage to be applied to the storage element representative of a voltage level less than the received voltage level. The apparatus further includes a voltage ramp circuit that applies a voltage ramp signal to the storage element for increasing an amount of voltage held in the storage element while simultaneously reading a voltage level of the storage element to determine whether the voltage of the storage element matches the target voltage and a comparator that deactivates the voltage ramp signal when the voltage of the storage element matches the target voltage.

Abstract: The present invention is an improvement in an analog storage device having a row of EEPROM cells. The improvement includes providing a reference EEPROM cell having first and second transistors connected in series, with a gate of the first transistor connected to a clear input line and a gate of the second transistor connected to a select input line. The improvement further includes providing a comparator having first and second inputs with the first input connected to a source of the second transistor and a second input connected to a reference voltage line and with an output of the comparator connected to the gate of the first transistor, wherein the gate of the first transistor is connected to gates of first transistors of each of the row of EEPROM cells.

Abstract: This invention utilizes the small cell size of the NAND storage cell structure in an analog storage and playback device. This is achieved, in part, by using a special, zero current storage cell, in which in the read mode, the cell loading current is waveshaped to attain an optimal dynamic range and to avoid the resistive effects of series parasitic resistances of other transistors in the source node or drain node, and to avoid the transistor conductance variations of all the transistors in the read path. The loading current is waveshaped to reduce possible overshoot and settling effects to achieve the fine output voltage resolution in an optimal sensing time. Details of the method and alternate embodiments are disclosed.

Abstract: The present invention discloses methods and apparatus for implementing a clocked high voltage switch involving MOS devices. The switching is from a high voltage source typically at 21V to ground. An intermediate voltage source typically at 11V is introduced for reducing the gated breakdown voltage requirement to approximately 10V. This reduced gated breakdown voltage requirement is easily met by special layout methods applied to various transistors in the circuit. The basic layout methods include the terminating of the field implant region near the N+P junction to expose the N+ diffusion over the P substrate to increase the junction breakdown and the gated diode breakdown, and the use of short channel length to reduce the threshold voltage.

Abstract: A redundancy circuit used in a non-volatile memory chip to increase the production yield due to manufacturing defects. The redundancy circuit includes a redundancy predecoder circuit, a source follower EEPROM (electrically erasable programmable read only memory) memory fuse, a scheme to use the column high voltage drivers (also known as page latch) to program the EEPROM fuses, a scheme to use the regular row decoder (also known as wordline driver or x-decoder) as the redundancy row decoder, and an out-of-bound address as a redundancy enable/disable signal.

Abstract: An integrated circuit which operates to store an input analog signal within an analog storage device such as an EEPROM is disclosed. Initially, a target voltage is determined for applying to the memory cell with the target voltage set to about 90% of the input analog signal voltage. A high voltage ramp is applied to the memory cell to set the voltage of the memory cell to the target voltage. A read operation is simultaneously performed while the high voltage ramp is applied to detect the voltage stored on the cell and to terminate the application of the high voltage ramp once the target voltage is reached. Thereafter, a normal read operation is performed on the memory cell to detect the actual voltage of the cell. A new target voltage is determined based upon the actual voltage of the memory cell and the input analog signal voltage. The high voltage ramp is again connected to the memory cell to set the cell to the new target voltage while a simultaneous read operation is performed.

Abstract: Method and apparatus for adjustment and control of an iterative method of recording analog signals with on-chip trimming techniques for later playback. The invention allows setting of various parameters for the multi iterative programming technique after chip fabrication so as to allow tighter control and thus higher resolution analog signal sample storage in a given or minimum amount of time. Such parameters include, but are not limited to: the step down voltage from the coarse programming cycle to the fine programming cycle, the incremental voltage increase between each fine pulse, the pulse width of each fine pulse, the number of fine pulses, the incremental voltage increase between each coarse pulse, the pulse width of each course pulse, the number of coarse pulses, and the offset, VOS, which stops further coarse pulses and holds the last coarse level as a reference for the following fine cycle.

Abstract: For use in integrated circuit systems wherein both filter time constants and oscillator frequency each need a suitable reference, both the filter and the oscillator are referenced to common reference circuitry through a suitable control loop. Because the fundamental control parameters of the oscillator and the filter are time-period and time-constant respectively, the oscillator and the filter are implemented in a manner where the monolithic passive elements setting the fundamental control parameters (time-period and time-constant) are of the same type. This has the advantage of close tracking through process and ambient variations. Monolithic capacitors on the same chip are used as one of the common passive elements between the oscillatorand the filter to set the time-period and time-constants, respectively, adjustable through adjustment of control currents.

Abstract: Integrated circuit system for analog signal recording and playback having improved performance and a very high level of integration. The integrated circuit is complete with preamplifier, automatic gain control, filter, fixed references including a band gap reference, trimming, power output amplifier, memory array, multiple closed loop sample and hold circuits, column decoder, column driver, row decoder, address counters, master oscillator and chip function timing circuits including sample clock, charge pumps, high voltage regulator and waveshapers, low VCC detector, power-on reset and recording reference circuits on a single chip. The system uses a writable analog reference scheme to put many error sources in the common mode, and provides a double ended output for maximum power output in a limited voltage range, and to allow direct connection to a speaker.

Abstract: Source follower storage cell and improved method and apparatus for iterative write for integrated circuit analog recording and playback which provides increased resolution in the stored signal and increased accuracy and stability of the storage and readout capabilities of the device. The storage cell is configured wherein the electrically alterable MOS storage device is connected in a source follower configuration, which provides a one to one relationship between the variation in the floating gate storage charge and the variation in the output voltage, and for high load resistance, relative insensitivity to load characteristics. The write process and circuitry provides a multi iterative programming technique wherein a series of coarse pulses program a cell to the approximate desired value, with a series of fine pulses referenced to the last coarse pulse being used for programming the respective cell in fine increments to a desired final programming level. Still finer levels of programming can be used.

Abstract: Cascading analog record/playback devices allowing the recording and the playback duration of individual devices to be extended by connecting together multiple devices of the same type. Each such device contains both writing and reading circuits as well as memory circuits. The memory is embedded inside the device and does not have direct access to the outside of the device. All control functions relating to the selection of particular devices is done by the devices themselves without external intervention or assistance. A single input circuit and a single output circuit is used by all devices. In the case of a voice record and playback system, all devices use a single microphone and single loudspeaker.