561 results about "Gain stage" patented technology

A radio frequency power amplifier includes a feedback control system coupled to an input signal and a first feedback signal and configured to provide an output; a controlled supply configured to provide power that is controlled in accordance with a signal; and a radio frequency gain stage powered from the controlled supply, driven by the output from the feedback control system, and configured to provide an output signal at the radio frequency to a resonant load, where the first feedback signal corresponds to the output signal. Some embodiments include a sequencer in the feedback control system and others utilize an additional feedback loop to control the power provided by the controlled supply.

A harmonic suppression mixer for down converting an RF signal to a complex I and Q baseband signal that uses a plurality of switching mixers each with a gain stage to produce a sinusoidal weighted sum of the mixer outputs. Odd harmonics output by each switching mixer is suppressed in the composite signal. A low skew local oscillator (LO) clock generator creates multiple LO phases and drives the mixers. The mixer can be used in low noise direct conversion RF tuners. The mixer is configurable by programming gain stage coefficient values to achieve a variable number of effective mixers used in combination. At low tuning frequencies, all available mixers are programmed with unique coefficients and driven by different LO clock phases to achieve maximum harmonic suppression. At high tuning frequencies, some mixers are paralleled and duplicate coefficients are programmed or mixers are disabled to reduce the number of effective mixers.

Several embodiments of medical ultrasound handpieces are described each including a medical ultrasound transducer assembly. An embodiment of a medical ultrasound system is described, wherein the medical ultrasound system includes a medical ultrasound handpiece having a medical ultrasound transducer assembly and includes an ultrasonically-vibratable medical-treatment instrument which is attachable to a distal end of the transducer assembly. An embodiment of a medical ultrasound system is described, wherein the medical ultrasound system has a handpiece including a medical ultrasound transducer assembly and including a housing or housing component surrounding the transducer assembly. A method for tuning a medical ultrasound handpiece includes machining at least a distal non-threaded portion of an instrument-attachment stud of the transducer assembly to match a measured fundamental frequency to a desired fundamental frequency to within a predetermined limit. A method for making a medical ultrasound transducer assembly determines acceptable gains for gain stages of the transducer assembly.

A pipelined analog-to-digital converter (ADC) (30) with improved precision is disclosed. The pipelined ADC (30) includes a sequence of stages (20), each of which includes a sample-and-hold circuit (22), an analog-to-digital converter (23), and the functions of a digital-to-analog converter (DAC) (25), an adder (24), and a gain stage (27) at which a residue signal (RES) is generated for application to the next stage (20) in the sequence. A multiplying DAC (28) performs the functions of the DAC (25), adder (24), and gain stage (27) in the stage (20), and is based on an operational amplifier (29). Sample capacitors (C10, C20) and reference capacitors (C12₂, C22₂) receive the analog input from the sample-and-hold circuit (22) in a sample phase; parallel capacitors (C12₁, C22₁) are provided to maintain constant circuit gain. Extended reference voltages (V_REFPX, V_REFNX) at levels that exceed the output range (V₀+, V₀−) of the operational amplifier (29) are applied to the reference capacitors, in response to the digital output of the analog-to-digital converter (23) in its stage (20). The reference capacitors (C12, C22) are scaled according to the extent to which the extended reference voltages (V_REFPX, V_REFNX) exceed the op amp output levels (V₀+, V₀−). The effects of noise on the reference voltages (V_REFPX, V_REFNX) on the residue signal (RES) are thus greatly reduced.

A mixer circuit of the present invention includes a gain stage configured to receive a first signal and a modulated bias current, and in accordance therewith, produce an output signal, the gain stage generating a first current and receiving the modulated bias current from a bias circuit on a common node. The bias circuit includes an input configured to receive a second signal, and in accordance therewith, generate the modulated bias current. The mixer circuit also includes a current shunt circuit for generating a second current. The first current, the second current, and the modulated bias current are coupled to the common node. In one embodiment, the first signal is approximately a square wave, and the frequency of the first signal is one-third the frequency of the second signal.

A harmonic suppression mixer for down converting an RF signal to a complex I and Q baseband signal that uses a plurality of switching mixers each with a gain stage to produce a sinusoidal weighted sum of the mixer outputs. Odd harmonics output by each switching mixer is suppressed in the composite signal. A low skew local oscillator (LO) clock generator creates multiple LO phases and drives the mixers. The mixer can be used in low noise direct conversion RF tuners. The mixer is configurable by programming gain stage coefficient values to achieve a variable number of effective mixers used in combination. At low tuning frequencies, all available mixers are programmed with unique coefficients and driven by different LO clock phases to achieve maximum harmonic suppression. At high tuning frequencies, some mixers are paralleled and duplicate coefficients are programmed or mixers are disabled to reduce the number of effective mixers.

A wearable medical device and method of detecting clipping of ECG signals is disclosed. In one embodiment, the wearable medical device comprises a plurality of ECG sensing electrodes configured to sense an ECG of a patient and an ECG acquisition circuit electrically coupled to a pair of the plurality of ECG sensing electrodes and configured to provide an amplified and conditioned analog ECG signal, a programmable attenuation/gain stage electrically coupled between a first gain stage and a second gain stage, an ADC electrically coupled to the ECG acquisition circuit to receive and digitize the amplified and conditioned analog ECG signal and provide a digitized ECG signal, and a signal conditioning and control unit electrically coupled to the ECG acquisition circuit and the ADC to receive and monitor the digitized ECG signal and to detect clipping of the amplified and conditioned analog ECG signal based upon the digitized ECG signal.

A memory array includes wordlines, local bitlines, two-terminal memory elements, global bitlines, and local-to-global bitline pass gates and gain stages. The memory elements are formed between the wordlines and local bitlines. Each local bitline is selectively coupled to an associated global bitline, by way of an associated local-to-global bitline pass gate. During a read operation when a memory element of a local bitline is selected to be read, a local-to-global gain stage is configured to amplify a signal on or passing through the local bitline to an amplified signal on or along an associated global bitline. The amplified signal, which in one embodiment is dependent on the resistive state of the selected memory element, is used to rapidly determine the memory state stored by the selected memory element.

A low-dropout regulator comprises a high-gain error amplifier having a differential input stage and a single-ended output, a high-swing high-positive-gain second stage with input connecting to the output of the error amplifier and a single-ended output, a p-type MOS transistor with gate terminal connecting to the output of the second stage, source terminal connecting to the supply voltage, and drain terminal to the output of the low-dropout regulator. A first-order high-pass feedback network connects the output of the low-dropout regulator and the positive input of the error amplifier, and a damping-factor-control means comprising a negative gain stage with a feedback capacitor connects the input and output of this gain stage. A capacitor is connected between the output of the error amplifier and the output of the low-dropout regulator, while a voltage reference connects to the negative input of the error amplifier. The regulator does not require an off-chip capacitor for stability and has improved load transient response and power supply rejection ratio.

An amplifier having an active and passive gain stage connect to a load for driving a load according to a system analog input. A first embodiment of the amplifier in accordance with the present invention includes a logic network connected between a comparator network and a switching system, wherein the comparator network connects to the passive gain stage. Specifically, the active gain stage may include an active filter connected to receive an analog or digital input and provide a difference between the analog or digital input and the feedback signal relative to the gain factor of a gain unit connected to the active filter. The passive gain stage includes a passive filter. The logic network generates at least one switching signal which controls the switching system that includes at least one switching device to selectively provide power to the load. An output signal from the switching system provides output for the amplifier and is fed back to the active gain stage. In another embodiment, the output is a two-level signal and the passive and active filters are second order low pass filters, where the gain factor is about 25 or more. In yet another embodiment, the gain factor is approximately 250. Moreover, the amplifier may include a digital delta-sigma modulator connected to supply a two level input.

In low-voltage circuits, there is often insufficient voltage to use a current source to bias a transconductance amplifier stage. This is particularly true in mixers where a switching circuit must be stacked on top of the transconductance input stage. One way around this problem is to get "double-duty" out of the input differential pair, using it both for gain stage and for DC bias. This is done by AC coupling in a high-frequency input signal, while using a low-frequency, DC-coupled circuit to establish the proper bias level. One common technique is to use a simple current mirror scheme to establish the DC level. Proper biasing using this technique requires good matching of resistance. In some implementations of transconductance amplifiers, particularly those that use inductors as degeneration elements, series resistance of the inductor and interconnect resistance can cause significant errors in the bias current. This invention addresses that problem by using an operational amplifier with a current-sensing resistor and a low-frequency feedback loop to compensate automatically for any resistance errors. The operational amplifier drives the feedback voltage (generated in accordance with the sensed voltage at the current-sensing resistor and applied to one input of the operational amplifier) towards a reference voltage that is applied to the other input of the operational amplifier to bias the transistor(s) in the transconductance amplifier for desired operating conditions.

A generator for use with an electrosurgical device is provided. The generator has a gain stage electrically disposed between a first voltage rail and a second voltage rail, wherein the gain stage includes an input and an output. A voltage source operably coupled to the gain stage input and configured to provide an input signal thereto responsive to a drive control signal is also provided. The generator also has one or more sensors configured to sense an operational parameter of the amplifier and to provide a sensor signal corresponding thereto and a controller adapted to receive the sensor signal(s) and in response thereto provide a drive control signal to the voltage source. The generator has an amplifier output configured to supply an output voltage corresponding to the first voltage rail and the second voltage rail when the output of the gain stage falls between a voltage of the first voltage rail and a voltage of the second voltage rail and is configured to supply a peak voltage output when the voltage output is falls greater than the voltage of the first voltage rail or less than the voltage of the second voltage rail.

An integrated circuit (IC) current sensor that self-calibrates to adjust its signal gain when employed in a current divider configuration is presented. The current sensor includes an integrated current conductor, a magnetic field transducer, a controllable gain stage and a calibration controller. The integrated current conductor is adapted to receive a portion of a calibration current. The calibration current corresponds to a full scale current. The magnetic field transducer, responsive to the calibration current portion, provides a magnetic field signal having a magnitude proportional to a magnetic field generated by the calibration current portion. The controllable gain stage is configured to amplify the magnetic field signal with an adjustable gain to provide an amplified magnetic field signal. The calibration controller is responsive to a calibration command signal to adjust the adjustable gain of the controllable gain stage to a calibrated gain in order to provide the amplified magnetic field signal at a predetermined voltage level that corresponds to a desired current sensor output signal voltage level if the full scale current were received by the integrated current conductor.

A monolithic integrated circuit amplifier has a gain stage and a buffer stage. The buffer stage includes an output stage and two separate voltage supplies, the second of which has a greater magnitude than the first. Switching circuitry is included that is connected to the output stage via a regulator bus. When an output demand voltage is less than a switch-over threshold, current to the output stage is provided substantially from the first voltage supply; when the output demand voltage is greater than the switch-over threshold, current to the output stage is provided substantially from the second voltage supply. Collector voltage at the output stage is dynamically controlled to be greater than the emitter voltage by a difference voltage that increases proportionally as output voltage increases above the switch-over threshold. This difference voltage is commonly referred to as "headroom." The dynamic headroom control circuitry preferably includes means for predictably setting and controlling the headroom voltage at switch-over and smoothly increasing the headroom voltage up to maximum output voltage.

Techniques to linearly (in dB) adjust the gains of variable gain elements (i.e., variable gain amplifiers or VGAs) in a receiver or transmitter. An input control signal is provided to a conditioning circuit that conditions the control signal to achieve various signal characteristics. The input control signal is limited to within a particular range of values, temperature compensated, scaled (or normalized) to the supply voltages, shifted with an offset, or manipulated in other fashions. The conditioned signal is then provided to an input stage of a linearizer that generates a set of exponentially related signals. This is achieved using, for example, a differential amplifier in which the conditioned control signal is applied to the inputs of the differential amplifier and the collector currents from the differential amplifier comprises the exponentially related signals. An output stage within the linearizer receives the exponentially related signals and, in response, generates a gain control signal. By approximately matching the output stage to a gain stage of the variable gain element and by using the gain control signal generated by output stage, the gain transfer function of the VGA approximates that of the exponentially related signals.

A digital audio processor (20) for a digital audio receiver (21) having an improved automute sequence is disclosed. The digital audio processor (20) includes automute detection circuitry (42) that monitors the amplitude of digital audio signals before and after the application of digital filters by digital audio processing circuitry (20d). The amplitude of the input signals are compared against a first threshold level, while the amplitude of the output signals are compared against a second threshold level. In response to the amplitude of the input signals for all of the audio channels (44) falling below the first threshold for a selected time period, a gain stage (50) in each channel ramps down the volume to a mute level, and pulse-width-modulation circuitry (54) is disabled. If the output signal amplitude falls below a second threshold for a channel, the pulse-width-modulation circuitry (54) for that channel is disabled. Hysteresis for the input signal amplitude is preferably added into the automute exit determination.

A method, apparatus, and system for dynamic range estimation of imaged scenes for automatic exposure control. For a given exposure time setting, certain areas of a scene may be brighter than what a camera can capture. In cameras, including those experiencing substantial lens vignetting, a gain stage may be used to extend dynamic range and extract auto-exposure data from the extended dynamic range. Alternatively, dynamic range can be extended using pre-capture image information taken under reduced exposure conditions.

An exemplary fast start-up crystal oscillator with reduced start-up time. The exemplary oscillator reduces the start-up time (i.e., the time taken to attain sustained stable oscillations after the power is turned on) by increasing the negative resistance of a circuit. Increasing the negative resistance increases the rate of growth of the oscillations, thereby reducing start-up time. The exemplary crystal oscillator includes a gain stage with negative resistance. A crystal with shunt capacitance is placed in the feedback loop of the gain stage. A buffer is coupled to the gain stage such that it blocks the crystal shunt capacitance from loading the gain stage, effectively increasing the negative resistance of the gain stage. Further, an oscillation detection and control circuit is coupled between the crystal and the gain stage. The oscillation detection and control circuit connects the buffer during start-up, and disconnects the buffer once an oscillation signal attains sustained stable oscillations.