3230 results about "Preamplifier" patented technology

A reliable, safe, accurate, low noise, inexpensive, portable amplifier circuit is adapted to accurately amplify both AC and DC neural response signals. A patient or subject is electrically connected to a multi-channel system for electrically measuring the patient's AC and DC neural response signals at a plurality of locations using electrodes connected through a multi-electrode cable. The neural response signals are input to a digital DC amplifier to filter, amplify and digitize the neural response signals. Digitized neural response signals are converted to optical signals and transmitted via a fiber optic cable to an interface that is preferably connected to a patient stimulus generator (e.g., a Ganzfeld stimulator or pattern stimulator for multi-focal ERG). The system also includes a stand-alone computer such as an IBM® compatible Personal Computer (PC) for two-way communication with the interface via a standard data interface cable (e.g., a USB cable). In the preferred embodiment, a digital DC amplifier is worn by the patient and receives each neural response signal at a two-conductor balanced input; a surge suppression circuit limits excessive voltage transients at the input. The neural response signal is next input to a balanced buffer amplifier stage for impedance matching and the buffered neural response signal is then input to a balanced, adjustable pre-amplifier stage having an adjustable gain which can be varied (e.g., from ×1 to ×64). The buffered, amplified neural response signal is then digitized for storage in a memory and transmission to a fiber-optic digital transmission circuit. An adjustable impedance element generates a DC offset compensation signal used to control a D.C. offset compensation amplifier to generate an offset control signal for input to gain-adjustable pre-amplifier stage, to maximize sensitivity and usable dynamic range.

Methods and systems for receiving different types of signal formats from different ultrasound transducers are provided. A base unit of an ultrasound system includes a connector and receiver circuit for connecting with one of multiple different types of transducers. For example, a conventional transducer providing analog information associated with a single element on one receive channel is connected with the connector and receiver circuit. Alternatively, a transducer outputting time division multiplex or other multiplex information representing multiple transducer elements is connected with the connector and receiver circuit. The receiver circuit processes the received information differently depending on the data format. For example, the preamplifier impedance or gain is different for single element signals versus time division multiplex signals. As another example, a low pass filter bandwidth is larger for time division multiplex signals than for signals representing a single element. Receive circuits with an analog-to-digital converter positioned prior to a digital demultiplexer are also included for use with multiplexed data formats. Time division multiplex or other multiplex signals from a transducer array are converted to a digital format prior to demultiplexing. Methods and systems for adapting multiplexing or processing of multiplexed signals are also provided. A test signal or ultrasound signals are transmitted from a transducer to the receiver circuit and analyzed. The multiplexer of the transducer is synchronized with an analog digital converter with selectable delays responsive to the analysis. Coefficients or other filter characteristics of a digital equalizer are selected as a function of the analysis.