Abstract: A voltage measurement apparatus is provided that includes: a potential attenuator configured to be electrically connected between first and second conductors, which are electrically coupled to a source, wherein the potential attenuator includes a first impedance and a reference impedance arrangement in series with each other, wherein the reference impedance arrangement has an electrical characteristic that can be changed in a known fashion; and further including a processing arrangement configured to acquire at least one signal from the reference impedance arrangement, the at least one signal reflecting change of the electrical characteristic in the known fashion; and to determine a voltage between the first and second conductors in dependence on the fashion in which the electrical characteristic is changed being known and the at least one signal.

Abstract: An operational amplifier circuit includes: a first differential amplifier section containing a P-type differential pair of P-type transistors; a second differential amplifier section containing an N-type differential pair of N-type transistors; an intermediate stage connected with outputs of the first and second differential amplifier sections and containing a first current mirror circuit of P-type transistors, and a second current mirror circuit of N-type transistors; and an output stage configured to amplify an output of the intermediate stage in power. The first differential amplifier section includes a first current source and a first capacitance between sources of the P-type transistors of the P-type differential pair and a positive side power supply voltage. The second differential amplifier section includes a second current source and a second capacitance between sources of the N-type transistors of the N-type differential pair and a negative side power supply voltage.

Abstract: A method for reducing the non-linearity effect of a digital-analog converter on an electronic interface circuit of a capacitive sensor. The electronic circuit includes an amplifier connected to the common electrode by a switching unit, a logic unit connected to the amplifier for supplying first and second digital measuring signals, and a digital-analog converter for supplying a measuring voltage to the electrodes. The method includes firstly biasing the capacitor electrodes by the measuring voltage, then biasing the fixed electrode of the first capacitor at a regulated voltage and the fixed electrode of the second capacitor at a low voltage, then biasing the capacitor electrodes by the measuring voltage, and finally biasing the fixed electrode of the first capacitor at a low voltage and the fixed electrode of the second capacitor at a regulated voltage.

Abstract: Differential power amplifier circuitry includes a differential transistor pair, an input transformer, and biasing circuitry. The base contact of each transistor in the differential transistor pair may be coupled to the input transformer through a coupling capacitor. The coupling capacitors may be designed to resonate with the input transformer about a desired frequency range, thereby passing desirable signals to the differential transistor pair while blocking undesirable signals. The biasing circuitry may include a pair of emitter follower transistors, each coupled at the emitter to the base contact of each one of the transistors in the differential transistor pair and adapted to bias the differential transistor pair to maximize efficiency and stability.

Abstract: Differential amplifier circuits for LDMOS-based amplifiers are disclosed. The differential amplifier circuits comprise a high resistivity substrate and separate DC and AC ground connections. Such amplifier circuits may not require thru-substrate vias for ground connection.

Abstract: A clamping circuit for a class AB amplifier includes a reference voltage circuit, four NPN Darlington transistors having inputs coupled to the reference voltage circuit, and outputs for providing four clamped voltages and a split NPN Darlington transistor having an input coupled to the reference voltage circuit, and four separate outputs for providing four AC ground voltages.

Abstract: An amplifier includes a first transformer configured to output first differential signals, a first differential amplifier coupled to the first transformer, a second transformer coupled to the first differential amplifier, a second differential amplifier coupled to the second transformer, a third transformer configured to transform second differential signals output from the second differential amplifier to a single-ended output signal, and a first bias circuit configured to supply a first bias voltage to a first secondary coil of the first transformer, wherein the first bias circuit sets the first bias voltage to a voltage greater than or equal to a first voltage based on the input signal in a first operating area where power of the output signal is greater than or equal to a first power so that power-gain characteristics of the output signal become closer to characteristics where gain of the output signal becomes constant.

Abstract: An amplifier circuit includes an input terminal and an output terminal. A current sinking transistor includes a first conduction terminal coupled to the output terminal and a second conduction terminal coupled to a reference supply node. A voltage sensing circuit has a first input coupled to the input terminal and a second input coupled to the output terminal. An output of the voltage sensing circuit is coupled to the control terminal of the current sinking transistor. The voltage sensing circuit functions to sense a rise in the voltage at the output terminal which exceeds the voltage at the input terminal, and respond thereto by activating the current sinking transistor.

Abstract: Provided is a power amplifier which includes: a first transistor and a second transistor each having a first end connected to a first power source supplying a first voltage and to which signals having a same size but opposite polarities are input; a third transistor and a fourth transistor having first ends respectively connected to the first ends of the first transistor and the second transistor; and a fifth transistor having a first end connected to second ends of the third and fourth transistors and controlling oscillation of the third or fourth transistor.

Abstract: A differential amplifier is described that provides a high common mode rejection ration (CMRR) without requiring the use of precisely matched components. One variation employs a method of noise reduction to increase the SNR of the device. The differential amplifier may be used in an apparatus for measuring biopotentials of a patient, such as an electrode for measuring brain activity. The electrodes can communicate the measured biopotentials with a remote system for further processing, while providing electrical isolation to the patient.

Abstract: An operational transconductance amplifier for connection with multiple input voltage sources includes a resistance simulation unit, two current cancellation units, a first differential output unit, two current division units, and a second differential output unit. The resistance simulation unit is to simulate resistance. The two current cancellation units are to receive and convert the voltage of the input voltage sources into two first currents. The two first currents flow to two first output ends of the first differential output unit, respectively. The two current division units are to receive and convert the voltage of the input voltage sources into two second currents. The two second currents flow to two second output ends of the two second differential output units, respectively, and include the same potential as the two first currents.

Abstract: Embodiments and methods herein operate as two-stage voltage controlled current sources (i.e., dynamic current sources) operating in class AB mode. Phase-delayed current injection circuits are associated with first-stage bias, second-stage bias, or both. The current injection circuits operate to quickly re-charge inter-stage parasitic capacitance associated with the active side of the class AB dynamic current source shortly after that side becomes inactive. Doing so quickly dissipates an otherwise slowly-decaying residual drive signal to prevent the output stage from continuing to conduct after the associated side of the current source becomes inactive. Excessive current consumption and possible destructive operation of the output stage are mitigated as a result.

Abstract: A bias generation method or apparatus defined by any one or any practical combination of numerous features that contribute to low noise and/or high efficiency biasing, including: having a charge pump control clock output with a waveform having limited harmonic content or distortion compared to a sine wave; having a ring oscillator to generating a charge pump clock that includes inverters current limited by cascode devices and achieves substantially rail-to-rail output amplitude; having a differential ring oscillator with optional startup and/or phase locking features to produce two phase outputs suitably matched and in adequate phase opposition; having a ring oscillator of less than five stages generating a charge pump clock; capacitively coupling the clock output(s) to some or all of the charge transfer capacitor switches; biasing an FET, which is capacitively coupled to a drive signal, to a bias voltage via an “active bias resistor” circuit that conducts between output terminals only during portions of a wa

Abstract: A differential circuit topology that produces a tunable floating negative inductance, negative capacitance, negative resistance/conductance, or a combination of the three. These circuits are commonly referred to as “non-Foster circuits.” The disclosed embodiments of the circuits comprises two differential pairs of transistors that are cross-coupled, a load immittance, multiple current sources, two Common-Mode FeedBack (CMFB) networks, at least one tunable (variable) resistance, and two terminals across which the desired immittance is present. The disclosed embodiments of the circuits may be configured as either a Negative Impedance Inverter (NII) or a Negative Impedance Converter (NIC) and as either Open-Circuit-Stable (OCS) and Short-Circuit-Stable (SCS).

Abstract: Embodiments of the invention are generally directed to improving the slew rate of an amplifier as the amplifier charges or discharges a capacitive load. In one embodiment, the amplifier is coupled to a slew-enhancing circuit which uses a control signal from the amplifier to aid the amplifier when charging or discharging the load. For example, the control signal may be an internal voltage used by the amplifier to control circuit elements within the amplifier. By routing the control signal to the slew-enhancing circuit, the control signal biases the circuit elements within the slew-enhancing circuit to source a boost current when charging the capacitive load or sink the boost current when discharging the capacitive load.

Abstract: A device includes an amplifier and a first switched current sampler. The first switched current sampler includes a first transistor, a first capacitor, and first, second, and third switches. The first capacitor has a first terminal electrically connected to a gate electrode of the first transistor, and a second terminal electrically connected to a source electrode of the first transistor. The first switch has a first terminal electrically connected to a first current source, and a second terminal electrically connected to the gate electrode of the first transistor. The second switch has a first terminal electrically connected to the first current source, and a second terminal electrically connected to a drain electrode of the first transistor. The third switch has a first terminal electrically connected to the drain electrode of the first transistor, and a second terminal electrically connected to a first input terminal of the amplifier.

Abstract: Exemplary embodiments are directed to systems, devices, and methods for enhancing a telescopic amplifier. An amplifier may include a differential pair of input transistors including at least one transistor configured to receive a first input and at least one other transistor configured to receive a second input. The amplifier may further include a cascode circuit including a first pair of transistors coupled to the at least one transistor of the differential pair to form a first plurality of current paths configured to generate a first output. The cascode circuit may also include a second pair of transistors coupled to the at least one other transistor of the differential pair to form a second plurality of currents paths configured to generate a second output.

Abstract: An operational amplifier includes a selective differential stage including a first current mirror and a current distribution circuit. First and second legs of the first current mirror are responsive to current in first and second paths of the current distribution circuit, which distributes a tail current in response to a first signal received by a first input of the operational amplifier. Current in a first path of a selection circuit in the second path of the current distribution circuit is responsive to a second signal received by a second input of the operational amplifier. Current in the second path of the selection circuit is responsive to a third signal received by a third input of the operational amplifier. An output stage generates an output signal responsive to a difference between the first signal and one of the second and third signals.

Abstract: Biasing methods and devices for amplifiers are described. The described methods generate bias voltages proportional to the amplifier output voltage to control stress voltages across transistors used within the amplifier.

Abstract: Low power low noise input bias current compensation for an amplifier input stage is provided by recycling the tail current of the differential pair transistors. A local amplifier regulates the tail current and buffers the base current of the tail current transistor, which is mirrored back to the input transistors to provide input bias current compensation.

Abstract: An operational amplifier circuit includes an output stage circuit. The output stage circuit includes a first and a second output transistors, a capacitor unit, and a switch unit. A drain of the first output transistor is coupled to a drain of the second output transistor via an output terminal of the output stage circuit. The switch unit is coupled between gates of the first and the second output transistors and coupled to a first terminal of the capacitor unit. A second terminal of the capacitor unit is coupled to the output terminal of the output stage circuit. The switch unit determines to conduct a signal transmission path between the gate of the first output transistor and the first terminal of the capacitor unit or conduct a signal transmission path between the gate of the second output transistor and the first terminal of the capacitor unit according to a control signal.

Abstract: An amplifier for an output buffer includes an operational amplifier including a first input terminal, a second input terminal, and an output terminal, the operational amplifier is configured to generate an input bias current and amplify a voltage difference between signals applied to the first input terminal and the second input terminal, and to output the amplified voltage difference; and a self-bias circuit connected to the first input terminal and the second input terminal, the self-bias circuit is configured to generate first and second current paths when the voltage difference is equal to or greater than a predetermined voltage, to generate a tail current on the first or second current path, and to add the generated tail current to the input bias current of the operational amplifier, wherein the second input terminal is connected to the output terminal.

Abstract: A differential amplifier circuit that includes a negative resistor in parallel to synthesize a larger source resistance is disclosed. In one or more implementations, a differential amplifier circuit includes a first transistor and a second transistor. The first transistor is configured to receive a first differential input and the second transistor is configured to receive a second differential input. The differential amplifier circuit also includes a third transistor and a fourth transistor that form a pair of cross-coupled transistors coupled to the first transistor and the second transistor. The pair of cross-coupled transistors are configured to generate a negative impedance at an output node, and the negative impedance, combined with an impedance of the first transistor, is configured to generate a sufficient termination impedance for a transmission line electrically connected to the output node.

Abstract: A drive circuit of an organic light emitting display and an offset voltage adjustment unit thereof are provided. The offset voltage adjustment unit can be used in an operational amplifier of the drive circuit having a differential input stage, a bias stage, and an output stage. The offset voltage adjustment unit coupled between the bias stage and a ground including a resistor string and a plurality of latch units. The resistor string has a first-end, a second-end, and a plurality of resistors series-connected between the first-end and the second-end forming a plurality of junctions. The latch units are coupled between the junctions and the ground, respectively. The latch units are sequentially conducted to adjust a bias current of the bias stage according to a control signal. The latch units enter a latch state upon receiving a latch signal to calibrate an output offset voltage of the operational amplifier.

Abstract: A signal receiver includes a current source providing a current having a current value, a pair of active input devices, and a pair of resistors. Each active input device includes a control node, a first conduction node, and a second conduction node. One of the control nodes receives an input signal. The first conduction nodes are connected to each other and receive the current. One of the second conduction nodes serves as an output node. The active input devices output an output signal to a core circuit according to the current and the input signal. Each resistor has a resistance value. A target voltage value is determined according to the resistance value and the current value, such that a voltage swing of the output signal is limited within the target voltage value, and an operating voltage of the core circuit is substantially equal to the target voltage value.

Abstract: A differential circuit with a function to compensate the gain enhancement due to the self-heating of the transistor is disclosed. The differential circuit includes an equalizer unit coupled with one of paired transistors. The other of the paired transistor receives the input signal to be amplified. The base level, or the base-emitter bias, is oppositely modulated by the input signal through the common emitter, which causes the modification of the base current. The equalizer unit reduces the variation of the base level only in low frequencies where the self-heating effect of the transistor appears.

Abstract: An apparatus comprises a differential amplifier circuit and a current source. The differential amplifier circuit is configured to receive a voltage at an input, wherein the differential amplifier circuit generates an output voltage having a magnitude proportional to the received voltage over a voltage range to be measured at a specified output common mode voltage. The current source is electrically connected to an input of the differential amplifier circuit and is configured to subtract a midpoint of a voltage range of the battery voltage to be measured at the input of the differential amplifier, wherein a circuit supply voltage provided to the differential amplifier circuit and the current source is less than the voltage at the input.

Abstract: A differential amplifier provides an amplifier circuit including two differential pairs. A first differential pair is connected in series to a second differential pair. The second differential pair is connected in a crosswise manner at least indirectly to a differential output signal of the first differential pair. The first differential pair and the second differential pair form a first differential current path and a second differential current path. A first emulation device is connected in parallel to the first current path. A second emulation device is connected in parallel to the second current path.

Abstract: A system includes a first variable gain amplifier configured to receive an input signal and a first down-mixer coupled to the first variable gain amplifier. Also, the system includes a first current conveyor coupled to the first down mixer, where the first current conveyor includes a first cascode and a second cascode coupled to the first cascode. Additionally, the system includes a first channel filter coupled to the first current conveyor and a second variable gain amplifier coupled to the first channel filter.

Abstract: A bias circuit includes a first p-n junction element supplied with a current by a first current source connected to a low-voltage side of the first p-n junction element and a base terminal of a second transistor, a second p-n junction element supplied with a current by a second current source, the second current source connected to a low-voltage side of the second p-n junction element and a base terminal of a first transistor, the first and second transistors connected at their emitter terminals to a third current source and receiving base voltages generated by the first and second p-n junction elements, respectively. The second transistor and the first transistor constitute a differential pair in which, at a collector terminal of the second transistor, a current having a temperature coefficient that is substantially twice the temperature coefficient of the current of the second current source is obtained.

Abstract: A transistor has variation in a threshold voltage or mobility due to accumulation of factors such as variation in a gate insulating film which is caused by a difference of a manufacturing process or a substrate to be used and variation in a crystal state of a channel formation region. The present invention provides an electric circuit which is arranged such that both electrodes of a capacitance device can hold a voltage between the gate and the source of a specific transistor. Further, the present invention provides an electric circuit which has a function capable of setting a potential difference between both electrodes of a capacitance device so as to be a threshold voltage of a specific transistor.

Abstract: An operation amplifier (op amp) having a bias current detection circuit that monitors the bias current flowing in an output stage of the op amp. When the bias current detection circuit detects that too much current is being wasted, e.g., sunk to ground, then the amount of bias current is reduced. Similarly, when the bias current detection circuit detects that insufficient bias current is being supplied to the output stage of the op amp, the amount of bias current is increased. In one implementation, the output of the bias current detection circuit may be signals indicative of, respectively, too much bias current and too little bias current, wherein those outputs are supplied to a state machine which is configured to control the amount of bias current being supplied in a stepwise fashion.

Abstract: A sense amplifier system and sensing method thereof are provided. The proposed sense amplifier system includes plural sense amplifiers, each of which includes a first switch having a first terminal, a second terminal, and a bulk terminal electrically connected to the first terminal, a second switch having a first terminal electrically connected to the second terminal of the first switch, a second terminal, and a bulk terminal, a third switch having a first terminal electrically connected to the first terminal of the second switch, a second terminal, and a bulk terminal electrically connected to the bulk terminal of the second switch, and a fourth switch having a first terminal electrically connected to the bulk terminal of the first switch and a second terminal electrically connected to the bulk terminal of the third switch.

Abstract: The present disclosure relates to a power amplifier, the power amplifier including a first amplifier configured to form a common source by allowing sources of a plurality of first transistors to be commonly connected, a second amplifier configured to form a common source by allowing sources of a plurality of second transistors to be commonly connected and to be respectively connected in a cascode structure to the plurality of first transistors of the first amplifier, and a controller configured to be connected to a common gate node to short-circuit second harmonic impedance of the common gate.

Abstract: Sense amplifiers including bias circuits axe described. Examples include bias circuits having an adjustable width transistor. A loop gain of the bias circuit may be determined in part by the adjustable width of the transistor. Examples of sense amplifiers including amplifier stages configured to bias an input/output node to a reference voltage.

Abstract: When the frequency bandwidth of a high frequency signal to be amplified is changed, the linearity of a high frequency module deteriorates. A high frequency module has an amplifier circuit including an amplification transistor and a variable impedance circuit, and an output matching network. Based on an amplifying operation, the amplified high frequency signal will contain unwanted signals of secondary distortion components. In a frequency band that generates such unwanted signals of secondary distortion components, the output impedance of the amplifier circuit is changed so that the impedance will not match between the amplifier circuit and the output matching network. The output impedance of the amplifier circuit is changed by controlling the variable impedance circuit.

Abstract: A comparator circuit (FIG. 4) is disclosed. The circuit includes an amplifier circuit (300,302) arranged to produce an output signal (Vom,Vop). A first current source (312) is arranged to produce a first current through the amplifier circuit. A detector circuit (400) is arranged to produce a control signal (404) in response to a level of the output signal. A second current source (402) is arranged to produce a second current through the amplifier circuit in response to the control signal.

Abstract: Provided is an error amplifier. The error amplifier includes: an amplifying unit receiving first and second input signals and amplifying a voltage difference between the received first and second input signals; a first voltage generating unit generating first and second driving voltages for driving the amplifying unit; a second voltage generating unit generating first and second body voltages to implement a body biasing method; a cascode current source including first to fourth PMOS transistors to provide a bias current to the amplifying unit and the first voltage generating unit; and an output unit outputting a signal of the voltage difference amplified by the amplifying unit, wherein the first and third PMOS transistors receive the first body voltage through a body terminal and the second and fourth PMOS transistors receive the second body voltage through a body terminal.

Abstract: An operational amplifier module including an operational amplifier circuit, a rate-increasing circuit and an overdriving circuit is provided. The operational amplifier switches an input voltage to an output voltage and outputs the switched output voltage. The rate-increasing circuit receives the input voltage and the output voltage and increases the rate of switching the input voltage to the output voltage according to the difference between the input voltage and the output voltage. The overdriving circuit provides an overdriving voltage to the rate-increasing circuit and the operational amplifier circuit during an overdriving period according to a selection signal. The level of the overdriving voltage is higher or lower than the levels of the input voltage and the output voltage. Furthermore, a method for increasing the slew rate of the operational amplifier circuit is provided.

Abstract: An operation amplifier (op amp) having a bias current detection circuit that monitors the bias current flowing in an output stage of the op amp. When the bias current detection circuit detects that too much current is being wasted, e.g., sunk to ground, then the amount of bias current is reduced. Similarly, when the bias current detection circuit detects that insufficient bias current is being supplied to the output stage of the op amp, the amount of bias current is increased. In one implementation, the output of the bias current detection circuit may be signals indicative of, respectively, too much bias current and too little bias current, wherein those outputs are supplied to a state machine which is configured to control the amount of bias current being supplied in a stepwise fashion.

Abstract: An amplifier comprising at least one amplifying element (20a, 25a) and a biasing circuit (32a, 32b) for biasing the or each amplifying element with a bias voltage is disclosed. The biasing circuit (32a, 32b) is adapted to vary the bias voltage such that the or each amplifying element switches between non-switching and switching modes of operation in response to a bias control signal (4) passing through a threshold value.

Abstract: An automatically calibrated differential amplifier including: an input stage differential amplifier configured to receive a input differential signal, to differentially amplify the input differential signal to generate an input stage output differential signal, and to have an input stage bias current; and a replica stage differential amplifier configured to automatically calibrate the input stage bias current in response to process or environmental variations. The differential amplifier may be included, for example, in a comparator and a multilevel receiver.

Abstract: A method of improving the slew rate of an amplifier is described where a differential pair of transistors receives a differential first control signal and second control signal. The tail current for the transistors is provided by a tail current regulator. The same control signals are applied to a slew boost controller, whose output increases as the differential between the control signals increase. The tail current regulator generates a bias signal that sets a minimum tail current. The tail current is controlled to be the minimum tail current until the slew boost output signal exceeds a threshold, whereupon the tail current increases in response to an increasing differential between the control signals. Common mode rejection is not adversely affected by the slew boost controller generating a slightly varying current under common mode conditions due to the minimum tail current.

Abstract: Improved preamplifier circuits for converting single-ended input current signals to differential output voltage signals, including first and second transimpedance amplifiers with input transistors operating according to bias currents from a biasing circuit, output transistors and adjustable feedback impedances modified using an automatic gain control circuit, as well as a reference circuit controlling the bias currents according to an on-board reference current and the single-ended input or the differential output voltage signals from the transimpedance amplifiers.

Abstract: Aspects of the invention include an operational amplifier circuit having a construction of a rail-to rail input folded circuit and includes an N-MOS differential pair composed of a pair of N-channel type MOS-FETs connected to a pair of voltage input terminals, and a P-MOS differential pair composed of a pair of P-channel type MOS-FETs connected to the pair of voltage input terminals. In some aspects, a comparator determines whether an common mode input voltage to the N-MOS differential pair and the P-MOS differential pair is higher than a half of a power supply voltage or not, and either one of the N-MOS differential pair and the P-MOS differential pair is selectively operated according to the comparison result. Active loads are provided separately for the N-MOS differential pair and for the P-MOS differential pair.

Abstract: An operational amplifier may include a differential stage comprising two transistors whose gates are respectively linked to the two inputs of the operational amplifier. The sources of the two transistors may be linked to a first current source whose delivered current depends negatively on temperature variations and to a second current source whose delivered current is proportional to absolute temperature. The sum of these two currents may be less dependent on temperature, in that this link of the sources of the two transistors with the two current sources is effected respectively by way of two resistors, and in that the current which passes through the two transistors is imposed of proportional with temperature type, so as to allow substantially temperature-independent elimination of the offset voltage of the operational amplifier while obtaining a temperature-independent constant gain-bandwidth product.

Abstract: An electronic biasing circuit provides a DC bias voltage to a circuit to be biased. The biasing circuit has a first transistor and a second transistor. A gate of the first transistor is connected to a gate of the second transistor and supplies the DC bias voltage. A source of the first transistor is connected to a supply reference voltage. A source of the second transistor is connected to the supply reference voltage via a resistor element. The currents flowing through the first and second transistor are forced to be equal. A third transistor is connected in series with the first transistor and a fourth transistor is connected in series with the second transistor. Currents flowing through the third and fourth transistors are forced to be equal.

Abstract: A circuit is disclosed to enhance slew rate of an amplifier. An amplifier includes an output, a first input, and a second input in a differential pair configuration. A slew rate enhancer includes a first slew rate enhancer and a second slew rate enhancer. The first slew direction enhancer is configured to detect a first slew rate condition in a first direction responsive to the first input and the second input and provide additional current for a first side of the differential pair of the amplifier during the first slew rate condition. The second slew direction enhancer is configured to detect a second slew rate condition in a second direction responsive to the first input and the second input and provide additional current for a second side of the differential pair of the amplifier during the second slew rate condition.

Abstract: Exemplary embodiments are related to an envelope-tracking power amplifier. A device may include a first transistor of a plurality of transistors in a stacked configuration configured to receive a supply voltage varying with an envelope of a radio-frequency (RF) input signal. The device may further include a second transistor of the plurality in the stacked configuration coupled to a reference voltage and configured to receive a dynamic bias voltage varying inversely proportional to the supply voltage.

Abstract: The present invention relates to an operational amplifier having low power consumption, which comprises a differential circuit, an output-stage circuit, and a floating bias generating circuit. The differential circuit receives an input signal and produces a control signal. The output-stage circuit is coupled to the differential circuit and produces an output signal according to the control signal. The floating bias generating circuit is coupled between the differential circuit and the output-stage circuit and generates a floating bias according to the control signal for controlling the rising or lowering of the voltage level of the output signal. Accordingly, the operational amplifier can charge and discharge rapidly, and thus extending the applications of the operational amplifier. Besides, the floating bias generating circuit can limit the output current while the operational amplifier is driving, and thus achieving the purpose of low power consumption.