Abstract: An energy-efficient photoreceptor apparatus and a transimpedance amplifier apparatus having high energy-efficiency and low power consumption of which are achieved through multiple distributed gain amplification stages, adaptive loop gain control circuitry and unilateralization, thereby enabling fast and precise performance over a wide range of input-current levels. The high-energy efficiency, robust feedback stability and performance of the present invention can be utilized to achieve sub-milliwatt pulse oximeters and may be employed in other current-to-voltage amplification and conversion applications. The use of analog processing on the outputs of the photoreceptor apparatus also helps lower the overall power of pulse oximeters.

Abstract: An ultra-low-power circuit for wireless neural recording and stimulation is provided. The circuit includes a neural amplifier with adaptive power biasing for use in multi-electrode arrays and a decoding and/or learning architecture. An impedance-modulation telemetry system provides low-power data telemetry. Also, the circuit includes a wireless link for efficient power transfer, and at least one circuit for wireless stimulation of neurons.

Abstract: A microchip for performing a neural decoding algorithm is provided. The microchip is implemented using ultra-low power electronics. Also, the microchip includes a tunable neural decodable filter implemented using a plurality of amplifiers, a plurality of parameter learning filters, a multiplier, a gain and time-constant biasing circuits; and analog memory. The microchip, in a training mode, learns to perform an optimized translation of a raw neural signal received from a population of cortical neurons into motor control parameters. The optimization being based on a modified gradient descent least square algorithm wherein update for a given parameter in a filter is proportional to an averaged product of an error in the final output that the filter affects and a filtered version of its input. The microchip, in an operational mode, issues commands to controlling a device using learned mappings.

Abstract: A micropower neural amplifier with adaptive power biasing for use in multi-electrode arrays is provided. The micropower neural amplifier includes a low noise gain stage. The low noise gain stage is implemented using an amplifier and pseudoresistor elements.

Abstract: An analog storage cell circuit includes a switch that minimizes subthreshold conduction and diode leakage, as well as an accumulation-mode coupling mechanism to minimize overall switch leakage to minimize accumulation-mode leakage. In one embodiment, an analog storage circuit includes a sample and hold circuit including an amplifier having first and second inputs and a switch coupled to the first input of the amplifier. The switch includes a first switching device forming a core of the switch, a second switching device coupled to the first switching device to disconnect the first switching device from a first terminal during the hold phase, and a third switching device coupled to the first switching device to connect the first switching device to a second terminal during the hold phase to minimize accumulation mode conduction in the first switching device.

Abstract: A system and technique for providing to flexible, programmable frequency estimators and spectrum analyzers that can operate over extremely large bandwidths and yet provide high spectral resolution are described. The acquisition time and hardware complexity of one technique scale as O(N), where N denotes the number of frequency bins acquired. Embodiments are disclosed in which architectures are implemented using exponentially-tapered transmission lines and filter cascades.

Abstract: In accordance with an embodiment, the invention provides a spectral enhancement system that includes a plurality of distributed filters, a plurality of energy distribution units, and a weighted-averaging unit. At least one of the distributed filters receives a multi-frequency input signal. Each of the plurality of energy-detection units is coupled to an output of at least one filter and provides an energy-detection output signal. The weighted-averaging unit is coupled to each of the energy-detection units and provides a weighted-averaging signal to each of the filters responsive to the energy-detection output signals from each of the energy-detection units to implement distributed gain control. In an embodiment, the energy detection units are coupled to the outputs of the filters via a plurality of differentiator units.

Abstract: A method and system processes a speech signal. A fast Fourier transform is performed on a speech signal to produce a speech signal having a plurality of frequency bands in a frequency domain.

Abstract: A low power high dynamic range microphone amplification system is disclosed. The system includes a current sensing amplifier for receiving an input current signal representative of auditory information and for providing an amplifier output signal. The current sensing amplifier includes a DC bias network that includes a cascode filter.

Abstract: In one aspect, the invention is a far-field power extraction circuit which includes an integrated antenna and impedance matching portion and a rectifier portion. The antenna and impedance matching portion includes an antenna configured to be responsive to a propagating electromagnetic signal and which provides a resonant response at a resonant frequency. In response to the electromagnetic signal, the antenna provides an electromagnetic output signal at an antenna port. The antenna and impedance matching portion is configured to match an antenna impedance with a remainder of the far-field power extraction circuit including the rectifier portion of the power extraction circuit coupled to the antenna and impedance matching portion. The rectifier is configured to rectify the electromagnetic output signal provided by the antenna to produce a direct current (DC) voltage at an output of the rectifier.

Abstract: A method and apparatus for performing far-field power extraction are presented. The method includes receiving an electromagnetic radiation signal, rectifying the signal to produce a direct current (D.C.) voltage and providing the D.C. voltage to a circuit. A far-field power extraction circuit includes an antenna for receiving an electromagnetic radiation signal, a rectifier for rectifying the electromagnetic radiation signal. The circuit may further include a charge pump for amplifying the rectified voltage, an impedance matching network for coupling the antenna to the rectifier and a feedback tuning circuit for optimizing performance of the extraction circuit.

Abstract: A logarithmic analog-to-digital converter system is disclosed. The system includes a transconductor for receiving an input signal and for producing a transconductor output signal at a transconductor output, a logarithmic circuit unit that is coupled to an input of the transconductor, a comparator amplifier for receiving the transconductor output signal and for producing a comparator amplifier output signal at a comparator amplifier output, and an integrating capacitor coupled to the transconductor output signal.

Abstract: An envelope detector system is disclosed for detecting an envelope in a system input signal. The envelope detector system includes an input node for receiving an input voltage signal, a transconducting amplifier for receiving the input voltage signal and producing an input current signal, a current mirror network for receiving the input current signal and for producing a current output signal, a capacitor for receiving the current output signal, and a rectifier output node for providing a rectifier output current signal. The capacitor is coupled to an input of the transconducting amplifier. The rectifier output current signal is fed into the current-mode wide-dynamic-range peak detector. The peak detector produces the envelope detector output current signal.

Abstract: An analog storage cell circuit includes a switch that minimizes subthreshold conduction and diode leakage, as well as an accumulation-mode coupling mechanism to minimize overall switch leakage to minimize accumulation-mode leakage. In one embodiment, an analog storage circuit includes a sample and hold circuit including an amplifier having first and second inputs and a switch coupled to the first input of the amplifier. The switch includes a first switching device forming a core of the switch, a second switching device coupled to the first switching device to disconnect the first switching device from a first terminal during the hold phase, and a third switching device coupled to the first switching device to connect the first switching device to a second terminal during the hold phase to minimize accumulation mode conduction in the first switching device.

Abstract: An edge-triggered flip-flop circuit in which a pair of capacitors are alternately charged and discharged to voltages approximating supply rail values and, in combination of with a small number of switches, present high or low impedance paths for input signal transitions of a predetermined polarity to trigger state changes. In an alternative embodiment large switching capacitors are avoided in a circuit that employs a pair of pass-transistor configurations to connect respective capacitors to output terminals of a bistable device. The voltages on the capacitors track the corresponding bistable device output voltages when the input signal is in a given state (illustratively low), and store the value of the corresponding voltage when turned off by the (illustratively high) other state of the input signal. Then, the voltage on the capacitors and the selected input signal transition is used to effectively trigger a transition in the bistable device.

Abstract: An apparatus having a circuit coupled to the gate contact of field effect transistor wherein the transistor's gate includes a dielectric layer of which at least a portion is an organic dielectric. The circuit is configured to produce one or more storage voltage pulses that cause charge to be stored in the dielectric layer. The field effect transistor has a semiconductor layer with a conductive path whose conductivity changes for a given Vg in response to storing the charge. The circuit may produce one or more dissipation voltage pulses having a voltage of opposite sign to the one or more storage pulses, that cause dissipation of charge stored in the dielectric layer. Further disclosed are a memory and a method of electronically storing and reading information, both utilizing the organic-based polarizable gate transistor apparatus.

Abstract: A logarithmic analog-to-digital converter system is disclosed. The system includes a transconductor for receiving an input signal and for producing a transconductor output signal at a transconductor output, a logarithmic circuit unit that is coupled to an input of the transconductor, a comparator amplifier for receiving the transconductor output signal and for producing a comparator amplifier output signal at a comparator amplifier output, and an integrating capacitor coupled to the transconductor output signal.

Abstract: A spectral enhancement system is disclosed that includes an input node for receiving an input signal, at least one broad band pass filter coupled to the input node and having a first band pass range, at least one non-linear circuit coupled to the filter for non-linearly mapping a broad band pass filtered signal by a first non-linear factor n, at least one narrow band pass filter coupled to the non-linear circuit and having a second band pass range that is narrower than the first band pass range, and an output node coupled to the narrow band pass filter for providing an output signal that is spectrally enhanced.

Abstract: An optical transient sensor circuit includes a photodiode in series with a MOS feedback transistor connected across a voltage difference. An inverting amplifier having its input connected to the common connection between the photodiode and the MOS feedback transistor and its output connected to an output-node for a measure of the incoming irradiance. A charge/discharge circuit, having an input connected to the output of the inverting amplifier, having an output connected to the gate of the MOS feedback transistor and having a first and second output for half-wave rectified and thresholded contrast encoding measures of positive and negative irradiance transients. A capacitor connected between a constant potential and the gate of the MOS feedback transistor.

Abstract: In accordance with an embodiment, the invention provides a spectral enhancement system that includes a plurality of distributed filters, a plurality of energy distribution units, and a weighted-averaging unit. At least one of the distributed filters receives a multi-frequency input signal. Each of the plurality of energy-detection units is coupled to an output of at least one filter and provides an energy-detection output signal. The weighted-averaging unit is coupled to each of the energy-detection units and provides a weighted-averaging signal to each of the filters responsive to the energy-detection output signals from each of the energy-detection units to implement distributed gain control. In an embodiment, the energy detection units are coupled to the outputs of the filters via a plurality of differentiator units.