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403results about "Amplifiers with impedence circuits" patented technology

Liquid crystal display device

InactiveUS6313819B1Large variation in amountVariation in outputStatic indicating devicesAmplifiers with impedence circuitsLiquid-crystal displayEngineering
In a source follower circuit having an NMOS source follower transistor with a drain thereof connected to a power supply and a current supply connected across the source of this transistor and earth, one end of a capacitor is connected to the gate of the transistor, the first analog switch is connected across the gate of the transistor and a precharge supply, the second analog switch is connected across the other end of the capacitor and the source of the transistor, and the third analog switch is connected across the other end of the capacitor and a signal source.
Owner:SONY CORP

Feedback-type amplifier circuit and driver circuit

Disclosed is a feedback-type amplifier circuit including feedback-type charging means, which operates as a voltage follower, having a differential stage which receives an input-terminal voltage and an output-terminal voltage differentially as inputs and charging means for performing a charging operation at the output terminal based upon an output from the differential stage; and follower-type discharging means for performing a discharging operation at the output terminal by follower operation of an active element in accordance with a voltage difference between the input-terminal voltage and the output-terminal voltage.
Owner:RENESAS ELECTRONICS CORP

Low dropout linear voltage regulator

The present invention discloses an LDO (Low DropOut) linear voltage regulator, which is based on an NMC (Nested Miller Compensation) architecture and can be capacitor-free, wherein an active resistor is added to the feedback path of the Miller compensation capacitor to increase the controllability of the damping factor, solve the problem of extensively using the output capacitor with a parasitic resistance, and solve the problem that a compromise must be made between the damping factor control and the system loop gain. Further, the present invention utilizes a capacitor-sharing technique to reduce the Miller capacitance required by the entire system and accelerate the stabilization of output voltage without influencing stability.
Owner:SITRONIX TECH CORP

Receiving circuit

A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of omegao existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8. In addition, the common wave extracting circuit 5 has transformers and, using its inductances, raises the difference between the common wave and the non-common wave within the circuit to more than two times that of a prior art.
Owner:PANASONIC CORP

Mixer having low noise, controllable gain, and/or low supply voltage operation

A mixer includes a reference current source, a programmable gain RF transconductance section or an RF transconductance section, switching quad native transistors or switching quad transistors, and a folded-cascoded common mode output section or an output section. When the mixer included the programmable gain RF transconductance section, the gain of the mixer is adjustable. When the mixer includes the switching quad native transistors, flicker noise of the mixer is reduced. When the mixer includes the folded-cascoded common mode output section, the mixer operates reliably from low supply voltages.
Owner:AVAGO TECH INT SALES PTE LTD

Frequency compensation techniques for low-power multistage amplifiers

A three stage amplifier is disclosed provided with a novel frequency compensation technique. Only a single feedback loop with a single compensation capacitance is provided. Instead of a conventional nested compensation technique, damping factor control is provided by means of a fourth gain stage in order to stabilize the amplifier. The resulting amplifier is particularly useful to drive large capacitive loads for low-voltage low-power applications.
Owner:THE HONG KONG UNIV OF SCI & TECH

Switched capacitor amplifier with higher gain and improved closed-loop gain accuracy

A switched capacitor CMOS amplifier uses a first stage non-inverting CMOS amplifier driving a second stage inverting CMOS amplifier. The first stage amplifier is provided with positive feedback to substantially increase the gain of the first stage amplifier. In the described examples, the positive feedback is provided either by connecting a capacitor from the output to the input of the first stage amplifier or by connecting a shunt transistor in parallel with an input transistor and driving the transistor from the output of the first stage amplifier. The substantially increased gain resulting from the positive feedback allows the gain of the switched capacitor amplifier to be set by the ratio of the capacitance of an input capacitor to the capacitance of a feedback capacitor. The amplifier also includes switching transistors for periodically discharging the input capacitor and the feedback capacitor.
Owner:MICRON TECH INC

Programmable mutlistage amplifier and radio applications thereof

A programmable multi-stage amplifier includes a 1st programmable amplifier, a 2nd programmable amplifier, and a control module. The 1st and 2nd programmable amplifiers are coupled in series to amplify an input signal. Each of the 1st and 2nd programmable amplifiers is operably coupled to receive independent gain control signals from the control module. The control module generates the gain control signals by determining the overall gain desired for the programmable multi-stage amplifier and a corresponding gain for each of the 1st and 2nd programmable amplifiers. The factors in which the control module makes this determination are based on an optimization of at least one of the power level of the programmable multi-stage amplifier, the noise factor for the programmable multi-stage amplifier, and / or linearity of the programmable multi-stage amplifier.
Owner:AVAGO TECH WIRELESS IP SINGAPORE PTE

Source follower capable of compensating the threshold voltage

A source follower capable of compensating the threshold voltage is provided. The source follower comprises a current source, a switching circuit, and a thin film transistor. The source follower makes the threshold voltage of the thin film transistor constant by using the current source, and makes the input voltage nearly equal to the output voltage by using the storage capacitor and the compensating capacitor. Thus, it can make the error of the output voltage fall in the error range of the gray level voltage.
Owner:INNOLUX CORP

System and Method for Capacitive Signal Source Amplifier

According to an embodiment, a system for amplifying a signal provided by a capacitive signal source includes a first stage and a second stage. The first stage has a voltage follower device including an input terminal configured to be coupled to a first terminal of the capacitive signal source, and a first capacitor having a first end coupled to an output terminal of the capacitive signal source. The second stage includes a differential amplifier capacitively coupled to the output terminal of the voltage follower device.
Owner:INFINEON TECH AG

Ultra-low-power pulse oximeter implemented with an energy-efficient photoreceptor

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.
Owner:SARPESHKAR RAHUL

Compensation circuit for amplifiers having multiple stages

A compensation circuit is provided for an amplifier including at least first and second amplifier stage. The circuit includes a first capacitance including one end that communicates with an input of the first amplifier stage. An amplifier includes a first gain, an input that communicates with an opposite end of the first capacitance, and an output. A second capacitance includes a first end that communicates with the output of the amplifier and an opposite end that communicates with an input of the second amplifier stage. A first impedence includes one end that communicates with the input of the first amplifier stage and an opposite end that communicates with an output of the second amplifier stage.
Owner:MARVELL ASIA PTE LTD

Nth Order Tunable Low-Pass Continuous Time Filter for Fiber Optic Receivers

According to one embodiment of the invention, a circuit comprising a plurality of operational transconductance amplifiers (OTAS) is described. The first OTA has differential input and differential output. The second OTA also has differential input, where a first output of the first OTA is coupled to the first differential input of the second OTA, which is an inverting input. A second output of the first OTA is coupled to the second input of the second OTA, which is a non-inverting input. The first differential output being coupled to a first input of the first OTA and the second differential output being coupled to a second input of the first OTA for negative feedback and current biasing.
Owner:LUMENTUM OPERATIONS LLC

Variable-gain constant-bandwidth transimpedance amplifier

A transimpedance amplifier (TIA) circuit according to the present invention includes a first opamp having an input and an output. A second opamp has an input that communicates with the first opamp and an output. A first feedback path communicates with the input and the output of the first opamp and includes a first resistance. A second feedback path communicates with the input and the output of the second opamp and includes a second resistance. A third feedback path communicates with the input of the first opamp and the output of the second opamp.
Owner:MARVELL ASIA PTE LTD

Method and apparatus for dynamic biasing of baseband circuitry in a communication system receiver

Baseband receiver circuitry is dynamically biased in a communication system receiver by generating gain control information, and controlling an adjustable bias of at least a portion of the baseband circuitry based at least in part on the gain control information. The baseband receiver circuitry comprises at least one amplifier having an adjustable bias associated therewith, with the adjustable bias of the amplifier being controllable utilizing a bias control signal. For example, the amplifier may be an operational amplifier having a gain stage and an output buffer stage, with the bias control signal being applied to the output buffer stage to control an adjustable bias current thereof. More specifically, the bias control signal may be used to control an amount of current provided by at least one of a plurality of current sources associated with the output buffer stage of the amplifier, for example, by controlling a switch which enables or disables one or more of the current sources. Advantageously, the dynamic bias control can substantially reduce power consumption in the receiver. The techniques of the invention can also be applied to other types of devices which utilize gain control.
Owner:CIENA +1

Communications receiver method and apparatus

A radiofrequency (RF) receiver circuit and method offer one or more performance improvements, such as an increased input compression point through better out-of-band interference suppression. In one example, an RF receiver circuit includes a low-noise amplifier (LNA) circuit and a mixer. The mixer output signal serves as negative feedback to the LNA circuit for improved compression point performance at interferer frequencies in or out of band with respect to a frequency of interest. Compression point performance is further improved for interferer signal components away from the frequency of interest by including at least one frequency-dependent circuit in the LNA circuit that is configured to reduce amplifier gain for such frequencies. The frequency-dependent circuit(s) may be tunable for different frequencies of interest. Additional improvements may be obtained by including a broadband input matching circuit and / or by including active mixer loads to increase the voltage conversion gain of the RF receiver circuit.
Owner:TELEFON AB LM ERICSSON (PUBL)

Frequency generator and communication system using the same

A frequency generator which can perform stable frequency oscillation unaffected by temperature variation. A frequency generator having a differential amplifier (1) having an LC resonance circuit (10) as a load and buffer circuits (21, 22) feeding back an output of the differential amplifier to its input, wherein a temperature coefficient converter (5) converting an output voltage of a reference voltage generator (4) and its temperature dependence to a voltage having a predetermined voltage and temperature coefficient and outputting it is provided to control bias currents IEF of emitter follower circuits to be in proportion to temperature variation. There are a characteristic in which delay time of the emitter follower circuits constructing the buffer circuits is in inverse proportion to a transconductance of transistors and a characteristic in which the transconductance is in inverse proportion to temperature and is in proportion to the bias currents IEF. An oscillation frequency stable to temperature variation can be obtained.
Owner:RENESAS TECH CORP

Low dropout linear voltage regulator with an active resistance for frequency compensation to improve stability

The present invention discloses an LDO (Low DropOut) linear voltage regulator, which is based on an NMC (Nested Miller Compensation) architecture and can be capacitor-free, wherein an active resistor is added to the feedback path of the Miller compensation capacitor to increase the controllability of the damping factor, solve the problem of extensively using the output capacitor with a parasitic resistance, and solve the problem that a compromise must be made between the damping factor control and the system loop gain. Further, the present invention utilizes a capacitor-sharing technique to reduce the Miller capacitance required by the entire system and accelerate the stabilization of output voltage without influencing stability.
Owner:SITRONIX TECH CORP

Low noise amplifier for wideband tunable matching

Provided is a low noise amplifier with a common source and a source degeneration, which has linearity, power gain, noise factor, and lossless input matching. The low noise amplifier includes: a first inductor having one terminal connected to an input terminal receiving a signal; a second inductor having one terminal connected to a ground; a MOS transistor having a gate connected to the first inductor, a source connected to the other terminal of the second inductor, and a drain transmitting a signal; and a variable capacitor connected between the source and gate of the MOS transistor and varying an input matching frequency at the input terminal.
Owner:ELECTRONICS & TELECOMM RES INST

Class d switching audio amplifier

A Class D switching audio amplifier incorporating four state modulation, input-to-output drive and feedback signal isolation, dual topology output filtration, and a low inductance board layout. The four state modulation results in a common mode voltage in the absence of audio. The input-to-output isolation of drive and feedback signals allows for elimination of large power transformers in applications without user-accessible outputs. Such isolation may make use of optical isolators. The output filter includes common mode and differential topology filter stages. The low inductance board layout treats the amplifier and power supply boards as modules, and utilizes both sides of the amplifier board in order to minimize trace length.
Owner:EVENSTAR MERGERSUB INC

Nested transimpedance amplifier with capacitive cancellation of input parasitic capacitance

A nested transimpedance amplifier (TIA) circuit comprises a zero-order TIA having an input and an output. A first transconductance amplifier has an input that communicates with said output of said zero-order TIA and an output. A first feedback resistance has one end that communicates with said input of said zero-order TIA and an opposite end that communicates with said output of said first transconductance amplifier. A first feedback capacitance has a first end that communicates with said input of said zero-order TIA and a second end that communicates with said output of said zero-order TIA. A capacitance has one end that communicates with said input of said zero-order TIA.
Owner:MARVELL ASIA PTE LTD

Embedded IC test circuits and methods

A self-testing transceiver having an on-chip power detection capability is provided. The self-testing transceiver can include a semiconductor substrate and a transmitter having a high-power amplifier disposed on the substrate. The self-testing transceiver also can include a receiver disposed on the substrate for selectively coupling to an antenna. The self-testing transceiver can further include at least one power detector disposed on the semiconductor substrate for determining a power such as an RMS and / or peak-power of a signal at an internal node of the self-testing transceiver. Additionally, the self-testing transceiver can include a loopback circuit disposed on the substrate.
Owner:UNIV OF FLORIDA RES FOUNDATION INC

Continuous variable-gain low-noise amplifier

Continuous variable-gain low-noise amplifier. The amplifier continuously adjusts its gain between well-defined high and low values by using a cascode current-steering circuit to partition signal current between two different nodes of an output loading network. A shunt feedback network connected from an intermediate node of the loading network to the input provides negative feedback that linearizes the amplifier as its gain is decreased. The circuit degrades the noise figure at lower gains by varying the gain without directly dumping the signal current to the power supply. The circuit produces only small changes in input and output impedances and preserves an improved reverse-isolation cascode characteristic as the gain is controlled.
Owner:QUINTIC MICROELECTRONICS WUXI
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