Abstract: A feedback amplifier includes an operational amplifier having an input end and an output end. A first resistor is coupled with the input end of the operational amplifier. A second resistor has a first end coupled with the input end of the operational amplifier and a second end coupled with the output end of the amplifier. A voltage divider has a first end being operably coupled with the output end of the operational amplifier and a second end being analog grounded. In an embodiment, the feedback amplifier further includes a first switch coupled to the first end of the voltage divider and the output end of the operational amplifier, and a second switch coupled to an internal node of the voltage divider. In an embodiment, the feedback amplifier is configured to provide attenuation when the first switch is open and second switch is closed.

Abstract: A feedback amplifier includes an operational amplifier having an input end and an output end. A first resistor is coupled with the input end of the operational amplifier. A second resistor has a first end coupled with the input end of the operational amplifier and a second end coupled with the output end of the amplifier. A voltage divider has a first end being operably coupled with the output end of the operational amplifier and a second end being analog grounded. In an embodiment, the feedback amplifier further includes a first switch coupled to the first end of the voltage divider and the output end of the operational amplifier, and a second switch coupled to an internal node of the voltage divider. In an embodiment, the feedback amplifier is configured to provide attenuation when the first switch is open and second switch is closed.

Abstract: A multilevel analog recording and playback system is described. The analog recording and playback system provides a variety of analog processing functions to enhance system level integration. The analog recording and playback system is an fully configurable integrated device that includes a plurality of signal paths, a microphone automatic gain control (“AGC”) circuit, volume control and filtering circuit, speaker driver circuit, gain selectable analog input, auxiliary input and output paths, configurable summation amplifiers having mixing features, multilevel analog memory storage array, and user selectable programming duration.

Abstract: A text-to-speech conversion system that includes a first module to convert text into words, a second module to convert words into phonemes, a third module to map phonemes to sound units, and a storage unit to store speech representations for a library of sound units. The first, second, and third modules and the storage unit are implemented within a single integrated circuit to reduce size and cost. The system typically further includes a ROM to store the codes for the modules, a RAM to store the text and intermediate results, a processor to execute the codes for the modules, a control module to direct the operation of the first, second, and third modules. The storage unit may be implemented with a multi-level, non-volatile analog storage array and may be programmed with a new library of speech representations by a programming module.

Abstract: A multilevel analog recording and playback system is described. An analog processing circuit processes analog data. A storage circuit includes a non-volatile memory array, a switching circuit, and a communication interface. The non-volatile memory array stores analog and digital data. The switching circuit transfers the analog and digital data to and from the memory array. The communication interface allows a processor to exchange information with the device.

Abstract: A multilevel analog recording and playback system is described. The analog recording and playback system provides a variety of analog processing functions to enhance system level integration. The analog recording and playback system is an fully configurable integrated device that includes a plurality of signal paths, a microphone automatic gain control (“AGC”) circuit, volume control and filtering circuit, speaker driver circuit, gain selectable analog input, auxiliary input and output paths, configurable summation amplifiers having mixing features, multilevel analog memory storage array, and user selectable programming duration.

Abstract: An apparatus and method for achieving accurate temperature-invariant sampling frequencies in a device, such as, a multiple message non-volatile multilevel analog signal recording and playback system is described. An oscillator is used to generate an oscillation frequency. A bandgap voltage generator generates a zero temperature coefficient voltage reference (V(OTC)) that is independent of temperature. This V(OTC) is applied to the oscillator. A variable temperature coefficient voltage (V(TC)) that compensates for temperature coefficient variations of a resistor to which V(TC) is applied produces a stable oscillator current Iosc. Therefore, the stable oscillator current Iosc is likewise independent of the temperature coefficient variations of the resistor. The stable oscillator current Iosc is applied to the oscillator such that the oscillator generates a stable temperature-invariant oscillation frequency.

Abstract: A single chip, single or dual message multilevel analog signal recording and playback system is described. In one embodiment, the system comprises a record circuit, an analog storage array, a playback circuit, and a control circuit that independently controls signal storage segments and duration capability. The record circuit receives an audio signal and generates a filtered signal, which is stored in the analog storage array. The playback circuit is coupled to the storage array for retrieving the stored signal for playback. The system further includes a mixer circuit which receives an auxiliary signal and mixes the auxiliary signal with the stored signal during playback. The control circuit also features a novel audio, visual, and input/output functionality.