Abstract: An improved line driver and method for increasing the available signal transmit power on a transmission line are disclosed. The improved line driver achieves an available transmit power increase without increasing the maximum current in the line driver output stage. The output stage of the line driver may comprise a first amplifier, a second amplifier, and an integrated back-matching resistor network. In order to further increase the available transmit power; a protective semiconductor device may be added to a line driver output stage for each semiconductor device in the first and second amplifiers. A third embodiment of a line driver output stage in accordance with the present invention may comprise a combination of the integrated back-matching resistor network along with the protective semiconductor devices.

Abstract: A high fidelity audio amplifier is provided having a solid-state floating bridge output stage and a preceding solid-state driver stage configured to operate with negligible voltage fluctuations and minimal current fluctuations, resulting in reduced driver stage distortion, freedom from driver stage clipping, and high and linear impedance at the driver input terminals, without significant increase in circuit complexity. The voltage gain and current gain sections of the amplifier form self-contained units which may be separately housed and remotely operated to enhance utility and isolate sensitive voltage gain circuits from the radiated electrical noise and heat of the output stage.

Abstract: A transconductance amplifier for inductive loads and a relevant inductive load driving method, the amplifier having an input stage receiving a driving signal (set-point), a power stage connected downstream of the input stage and connected to the load and an output stage fedback on the input stage to transfer a signal associated to the load. Advantageously, the input stage comprises at least a comparator receiving on one input the driving signal and on another input the output of the output stage. A delay block is also provided between the comparator output and the power stage to delay the comparator switching. This can be obtained also by using a hysteretic comparator.

Abstract: A bridge amplifier includes a first input node connectable to a power source having an input voltage, a second input node connectable to a control source having a control voltage, and a first and a second output node. A first amplifier module having a gain is coupled between the first and second input nodes and between the first and second output nodes, and a second amplifier module is coupled to the first input node and between the first and second output nodes. The first amplifier module compares a voltage differential between the first and second output nodes to the control voltage and provides an output voltage at the first output node necessary to maintain the voltage differential at a level substantially equal to a product of the control voltage multiplied by the gain.

Abstract: A powered transducer preamplifier includes a preamplifier circuit that DC couples the preamplifier input with the preamplifier output. A biasing circuit is coupled to the preamplifier input to apply a bias voltage to power the transducer, and a DC level shifting circuit is DC coupled to the signal path of the preamplifier circuit between the input and the output to compensate for this bias voltage. The DC level shifting circuit avoids the use of reactive components, and thereby reduces phase distortion. A variety of DC level shifting circuits can be used, including a bridge circuit having four matched resistors and an inverter DC coupled between the nodes of the bridge.

Abstract: A bridged amplifier output stage capable of sharing a common conductor between independent loads. Multi-Channel pulse width modulated output signals are time division multiplexed to reduce the number of required conductors. The output stages are driven such that the non-common conductor time multiplexed off-channel(s) receives a copy of the shared common signal. The differential signal on the off-channel(s) is thereby cancelled even though the common conductor is carrying a signal for use by the on-channel.

Abstract: An RF power amplifier system is presented herein and it includes an RF source that provides an RF carrier signal having a given RF carrier frequency. An RF amplifier module amplifies the carrier signal and this module includes first and second RF amplifiers having a common input to receive a turn on signal that turns on both amplifiers and wherein the outputs of the amplifiers are coupled together in parallel. A controller supplies a turn on signal to the common input to turn on the first and second amplifiers. A first AC to DC supply provides a first DC operating voltage obtained from a first multiphase AC supply and applies this to the amplifier module and wherein the first DC voltage exhibits a ripple frequency dependent upon the number of phases in the first multiphase supply.

Abstract: A low noise, low distortion, power efficient DSL/cable line driver has a double Wheatstone impedance bridge network that functions to prevent contamination of DSL signals that are received by and transmitted from the line driver. The line driver employs an external current sensing impedance that can be either purely resistive or complex and that can be selected to accommodate a particular transmission medium. The line driver further employs an internal programmable resistor that can be programmably adjusted to accommodate changes in transmission medium impedance to optimize sidetone rejection.

Abstract: A circuit (40) and method for applying drive voltages to a voice coil motor (VCM) (22) of a mass data storage device (10) has two driver sets, each having a high side driver (HSD) (42,46) and a low side driver (LSD) (44,48) connected to the VCM (22). Each driver set has two SENSEFETs (50,52), each having a power FET and a sense FET. A circuit (106,104) is provided for sensing a sense current in the sense FET of the LSD, and a circuit (60,76,74) is provided for increasing the bias on the gates of the SENSEFET (52) in the LSD when the sense current falls below a predetermined level (VREF). Also, a circuit (113,114,110) is provided for driving a predetermined current in the SENSEFET of the HSD when the sense current falls below the predetermined level. Thus, a current at the predetermined level always flows in the SENSEFETs (50,52).

Abstract: An improved line driver and method for increasing the available signal transmit power on a transmission line are disclosed. The improved line driver achieves an available transmit power increase without increasing the maximum current in the line driver output stage. The output stage of the line driver may comprise a first amplifier, a second amplifier, and an integrated back-matching resistor network. In order to further increase the available transmit power; a protective semiconductor device may be added to a line driver output stage for each semiconductor device in the first and second amplifiers. A third embodiment of a line driver output stage in accordance with the present invention may comprise a combination of the integrated back-matching resistor network along with the protective semiconductor devices.

Abstract: A circuit for ensuring a complete saturation of both operational amplifiers of a single-input bridge amplifier is provided. A voltage divider is connected between the inverting inputs of the two amplifiers and a saturation current signal is injected on the intermediate node of the voltage divider. Such a saturation current signal is obtained through dedicated sensing devices of the state of saturation reached by the transistors of the output stages of both amplifiers of the single-input bridge amplifier.

Abstract: A power amplifier designed for delivering high power to a load (LOAD) comprises an input stage (A1) that converts an input voltage (u1) to a current signal (iin) which is applied to an end stage comprising a current amplifier stage (A3, PA1, PA2) and a bypass-resistor (R). The output terminal (7) of the current amplifier stage is connected to earth, and the current supply (PS1, PS2) is arranged floating relative to signal earth, so that the power current signal through the load (LOAD) also passes through the current supply (PS1 or PS2). A correction amplifier (A2) is preferably connected so as to measure the voltage across the end stage (A3, PA1, PA2) and provide a correction current (ikorr) to balance the voltage difference across the current amplifier stage and remove the effect of non-linearities in the current amplifier stage.

Abstract: The present invention is a circuit for use as a preamplifier or amplifier. The circuit has first and second input terminals that are configured to receive first and second balanced input signals. The circuit also includes first and second active devices that control output signals. Each of the active devices have a source, a control, and an output. In one embodiment, the control of the first active device is coupled to the first input terminal. The control of the second active device is coupled to the second input terminal. The circuit further includes first and second output terminals at which output signals are provided. The first and second output terminals are coupled to the first and second active devices. The circuit includes an coupler that couples a floating power supply to the first and second output terminals, and to the first and second active devices.

Abstract: A Class-D switching amplifier (20) having a terinary modulation scheme implemented in an H-bridge configuration. The present invention has four states of operation, and achieves increased efficiency and reduced cost by delivering current to the load only when needed, and once delivered, maintaining the current. The Class-D switching amplifier eliminates the need for post amplifier filters.

Abstract: A RF power amplifier system is presented herein including a RF source for providing a train of RF pulses exhibiting RF cycles of a fixed frequency and wherein each pulse is of a fixed amplitude and duration. A bridge circuit is provided and it includes a first transistor switch for, when on, connecting the DC voltage source across a load for DC current flow therethrough in a first direction and a second transistor switch for, when on, connecting the DC voltage source across the load for DC current flow therethrough in a second direction. A switch driver serves, when enabled, to pass the RF pulses for driving the first and second transistor switches on and off at a frequency dependent upon that of the RF pulses and in such a manner that current from the DC voltage source alternately flows in the first and second directions through the load.

Abstract: A highly linear, low-distortion H-bridge amplifier is described. The amplifier includes four interconnected power transistors connected to an inductive load. Each transistor has a precision voltage clamp connected between the source and drain to suppress ringing oscillations. Two or more of the transistors also include high-speed transient-voltage suppressers connected in parallel with their respective voltage clamps. These transient-voltage suppressers do not have the clamping accuracy of the voltage clamps, but respond much more quickly to suppress noise spikes. The amplifier therefore takes advantage of both the fast response time of the transient-voltage suppressers and the precise voltage-clamping characteristics of the voltage clamps.

Abstract: A seat weight measuring apparatus that simplifies the circuit configuration of the load sensors to reduce the circuit costs and which, when the load sensors fail, immediately detects the failure of the load sensors, thereby improving the reliability. In the case where four load sensors are arranged at four locations, for example front and rear on both sides, of the bottom of the automotive seat, the seat weight measuring apparatus includes two pairs of load sensors, a detection circuit for detecting a difference between outputs from the two antiphase-connected pairs of load sensors, and a seat weight calculator for calculating the weight of the automotive seat based on an output from the detection circuit. This can simplify the circuit configuration and eliminate problems of circuit costs and reliability.

Abstract: A circuit arrangement for amplifying a differential voltage signal in an output signal proportional to a voltage difference is provided, the voltages of a signal source that are to be compared being present at two inputs of the circuit arrangement, and a current signal proportional to the voltage difference being present at one output of the circuit arrangement, the circuit arrangement comprising cross-coupled transistors and the inputs being respectively connected to the base of one of the transistors, and a cross current of the circuit arrangement being present at the output. A compensation circuit is provided having a temperature behavior which corresponds to the temperature behavior of cross resistances of the circuit arrangement, the compensation circuit being associated with each of the inputs of the circuit arrangement.

Abstract: There is provided an audio power amplifier having an output DC isolated from ground between two capacitors which are connected in series across a bias potential. The bias potential may be generated from common AC line currents by a simple bridge rectifier without the need for a bulky power supply transformer. The amplifier is DC isolated from the input signal, and hence from ground, by a balun or other small-signal transformer. Feedback is provided to compensate for ripple appearing on the bias potential.

Abstract: There is disclosed a power amplification device for BTL-driving a load with a half-wave signal whose output direct current level is set close to an earth level, in which output signals of first and second output amplifiers (2) and (3) are added in an adder circuit (10). A higher output signal is selected from the two output signals and generated as an output signal c. Output currents of variable current sources (8) and (9) of the first and second output amplifiers (2) and (3) are controlled in response to the output signal c to change operating currents of the first and second output amplifiers (2) and (3). The operating currents are enlarged only when the output signals of the first and second output amplifiers (2) and (3) are enlarged. Thereby, the efficiency of the operating current of BTL drive type output amplifier is enhanced.

Abstract: A power amplifier comprises a pair of power-supply rails, a power-supply voltage divider, an intermediate power-supply line, a first and second BTL amplifiers, and a first to fourth switching circuits. The power-supply rails are composed of a first power-supply line to which a power-supply potential is applied and a second power-supply line to which the ground potential is applied. The power-supply divider produces an intermediate potential by dividing the voltage between the power-supply rails in two and supplies it to the intermediate power-supply line. The first BTL amplifier is provided between the second power-supply line and the intermediate power-supply line. The second BTL amplifier is provided between the first power-supply line and the intermediate power-supply line. The first and second BTL amplifiers each include an output bridge circuit.

Abstract: A method and circuitry for amplifying an input signal. First, second and third input signals are provided with the third input signal being the average of the first and second input signals. A ramp signal is provided using the third input signal as the ramp base signal and the first and second signals are compared with said ramp signal to provide an output responsive to only one of the first and second signals when the ramp signal and one of the first and second signals are equivalent. A load is driven in response to the output. In addition, an error signal can be provided by comparing the output with the first and second input signals and altering the first and second input signals as a result of comparing the output with the first and second input signals. The output is a function of the value of the ramp signal when the ramp signal and one of said first and second signals are equivalent.

Abstract: The present amplifier circuit employing floating error-cancellation technique eradicates errors and distortions by canceling them out at the speaker terminal. The circuit utilizes reference, main power, and error suspension amplifiers. The reference amplifier is a small signal amplifier with unity or near unity gain. The main function of the buffer amplifier is to provide a reference signal to be used to isolate the error signal. The main power amplifier is an inverting power amplifier without negative feedback, and whose main function is amplify the audio signal. The error suspension amplifier is a non-inverting power amplifier whose function is amplify the isolated error signal and provide an error potential to a speaker terminal so that the error can be canceled out at the speaker load.

Abstract: A low voltage differential swing driver circuit comprises first and second serially connected field effect transistors connected in series through first and second resistors. Third and fourth field effect transistors are serially connected together through third and fourth resistors. A diode connects one side of each of the serially connected transistors to one side of a source of regulated low voltage. A remaining side of the regulated low voltage source is connected to a remaining side of the serially connected transistors whereby differential currents are produced through the pairs of transistors. A voltage bias source is connected to a junction of said first and second resistors and to the junction of said third and fourth resistors. Control logic supplies a data switching signal to a gate of the first and fourth transistors, and a complementary data switching signal to a gate of said second and third transistors.

Abstract: A balanced bridge (full or half) power transconductance amplifier utilizes an input voltage signal to control current converter, in the form of a differential circuit, to derive a pair of control currents representative of the input signal and a load current monitoring signal. The converter includes a current input terminal which responds to a current representative of the load impedance for reducing the amplitude of the control currents (and the bridge current) due to an impermissibly low load impedance. A class A to class B converter responds to the control currents to provide a pair of discontinuous bridge drive currents with each drive current being proportional to the difference in the control currents during respective half cycles. A differential amplifier steers the bridge drive currents to respective legs of a full bridge in response to the voltages across the power supply terminal and the load to reduce any bridge unbalance.

Abstract: A low voltage differential swing circuit includes a clamping circuit to prevent the output high voltage from exceeding a reference voltage. The low voltage differential swing circuit also includes a current source coupled to a control node and a current steering circuit coupled between the control node and first and second output nodes. The current source provides a constant drive current, and in response to first and second input signals, the current steering circuit generates first and second drive currents, wherein the first and second drive currents together form at the first and second output nodes a differential output signal. The clamping circuit comprises a operational amplifier and a shunting circuit. The operational amplifier senses the difference between a reference voltage and a voltage level at the control node, which voltage level varies in relation to the voltage level of the differential output signal.

Abstract: A bridged driving amplifier for driving a capacitive load comprises a first and a second output terminal, and a first and a second supply rail. A first driving section is coupled between the first supply rail and the first output terminal. A second driving section is coupled between the second output terminal and the second supply rail. A third driving section is coupled between the first supply rail and the second output terminal. A fourth driving section is coupled between the first output terminal and the second supply rail. The bridged amplifier is AC-driven such that the first and the second section, when driven, cause an output voltage across the capacitive load of a given polarity, and that the third and the fourth section, when driven, cause an output voltage across the capacitive load of a polarity opposite to the given polarity.

Abstract: A driving circuit has first and second output terminals for connection with a load, for supplying the load with a constant voltage changing in polarity at predetermined timing, through the output terminals. A bridge circuit has first and second output nodes connected, respectively, to the first and second output terminals. A selector circuit selectively drives a plurality of current changeover switching elements of the bridge circuit. First and second differential amplifier circuits have first input terminals supplied with a predetermined reference voltage and second input terminals connected, respectively, to the first and second output nodes, and a common output terminal. A switching circuit selectively connects the first and second differential amplifier circuits to a power source in response to selective driving of the current changeover switching elements by the selector circuit.

Abstract: An amplifier and a method for detecting the presence of a load (3) in a bridge-type amplifier configuration, in which the amplifier includes two amplifying circuits (1, 2). A load detection sequence is combined with an activation sequence of the amplifier by providing, during activation of the first amplifying circuit (1), a low impedance (4) at the output (203) of the second amplifying circuit (2), and determining whether a current flows through the low impedance (4) or one of the outputs (103, 203) of the amplifying circuits (1, 2) during the activation of the first amplifying circuit (1).

Abstract: A bridge amplifier circuit comprising two amplifiers in bridge configuration having a feedback path from the output of one of the amplifiers to the reference input of the other amplifier, together with compensation means for reducing the voltage variation at the reference input. In this way offset and distortion are reduced, although the gain of the amplifier circuit is not affected by the presence of the feedback path.

Abstract: A high output power is obtained for an audio power amplifier using an amplifier circuit topology wherein channels or stages of a multi-channel class AB monolithic integrated circuit are paralleled in order to drive a low impedance dual voice coil speaker. The stages are paralleled by connecting their outputs through isolation resistors. These resistors prevent the differences in output bias voltages from resulting in a short circuit from power to ground. In addition, the resistors are sufficiently small to achieve the correct speaker damping factor, yet large enough to prevent excessive quiescent current. The separate amplifier channels or stages are paralleled through isolation resistors which increases current drive resulting in a higher output power to the loud speaker.

Abstract: A transformer-coupled amplifier includes a driver transformer in which a primary winding, a secondary winding, and a tertiary winding are wound on a core of a magnetic circuit, a drive signal source for supplying an AC drive signal superposed with a drive-stage DC current to the primary winding of the driver transformer, a power tube for extracting, from the secondary winding of the driver transformer, an AC signal corresponding to the AC drive signal supplied to the primary winding of the driver transformer, and for amplifying the AC signal from the secondary winding, and a DC magnetization control power source for supplying a predetermined magnetization control current to the tertiary winding of the driver transformer so as to change a degree of DC magnetization of the core of the magnetic circuit of the driver transformer. The DC magnetized state of the core of the transformer magnetized by the DC current is appropriately changed by the magnetization control current.

Abstract: The present invention provides a BTL amplifier device with low power consumption and high efficiency which comprises two units of amplifier, a transistor, and a load resistor, and is driven as claimed in output from an operational amplifier as well as from an inverting amplifier. Signals at both edges of the load resistor are supplied to a differential NFB circuit and a fed-back output is inputted to one of the operational amplifiers, while an output signal from the operational amplifier is converted by an absolute value circuit, and then a DC voltage is superimposed on the absolute value signal in a voltage shifting circuit.

Abstract: A recording apparatus including a magnetic write head and a write amplifier with capacitive current compensation. The write amplifier is made up of four current mirrors which are turned on two at a time by two switchable floating current sources connected between the input terminals of the current mirrors in order to produce a write current of alternating polarity through the write head. The parasitic capacitances across the write head and/or the parasitic capacitances of the write amplifier at the write terminals are neutralized by means of neutralizing capacitors. The high impedance at the terminals of the write head enables the common-mode voltage across the write head to be fixed at any desired voltage value by means of a common-mode circuit.

Abstract: A method of actuating a plurality of power amplifier devices in an Class D audio switching amplifier (100) using non-overlapping edge drive signals for preventing substantially high current spikes during switching transitions. The method includes actuating and deactuating power amplifier devices within a first complementary power switching device (117) and actuating and deactuating a second complementary power switching device (119) using a plurality of drive signals generated by a non-overlapping driver (107). The method provides that the first complementary power switching device (117) and the second complementary power switching device (119) are switched ON and OFF in a predetermined sequence such that more than one power amplifier device within each complementary power switching pair is prevented from being simultaneously activated. This prevents high current spiking and subsequently high current drain during a switching transition for conserving battery life when used with portable equipment.

Abstract: A signal amplifier includes four amplifier stages which can be arranged in two different configuration modes, a first configuration mode in which a series arrangement of two loads is arranged between output terminals of a first and a third one of the amplifier stages, a reference potential being applied to a node between the loads, a first signal to be amplified being applied to an input of the first amplifier stage, and a second signal to be amplified being applied to an input of the third amplifier stage, and a second configuration mode in which a first one of the loads is arranged between the output terminal of the first amplifier stage and an output terminal of a second amplifier stage, and a second one of the loads is arranged between the output terminal of the third amplifier stage and an output terminal of a fourth amplifier stage, and the first signal to be amplified being applied to an input of the first amplifier stage and an input of the second amplifier stage and the second signal to be amplified

Abstract: The present compensating circuit operates to reduce the span shift error due to ambient temperature changes of a span resistance compensated, bridge array circuit arrangement for a semiconductor transducer employing piezoresistive sensors. The span resistance method alone cannot reduce the span shift error to less than one percent (1%) for full scale. The present compensating circuit applies a constant voltage source, derived from the voltage source applied to the transducer, to a non-inverting input to an operational amplifier. The circuit also applies an ambient temperature dependent voltage, derived from the ambient temperature dependent bridge resistance of the bridge array circuit, to an inverting input of the operational amplifier. Both inputs to the operational amplifier are fed back through a different resistance loop to control the output voltage in response to the non-linearity of the ambient temperature dependent bridge resistance.

Abstract: An apparatus for recording on a magnetic record carrier includes a write amplifier comprising four current mirrors which are turned on two at a time by two switchable floating current sources connected between the input terminals of the current mirrors in order to produce a write current of alternating polarity through a write head. The high impedance at the terminals of the write head enables the common-mode voltage across the write head to be fixed at any desired voltage value by means of a common-mode circuit. The symmetrical structure further enables the parasitic capacitances at the write terminals to be neutralized by means of neutralizing capacitors.

Abstract: Distorting effects and disturbances caused by abrupt voltage changes on the output nodes of a pair of selfconfiguring amplifiers for alternatively driving in a bridge mode or in a single-ended mode by one amplifier of the pair a certain load, in dependence on the level of the input signal, because of the enabling/disabling of a common mode control loop, are effectively eliminated by storing the voltage of a common mode control node of the pair of amplifiers on a capacitance during a phase of disabling of said common mode control loop. Abrupt voltage drops and recoveries at the switching instants are prevented.

Abstract: An amplifier circuit and method of providing diagnostic testing to a Wheatstone bridge amplifier circuit are provided herein. The amplifier circuit includes a balanced circuit such as a Wheatstone bridge employed in a piezoresistive transducer which produces a differential output signal. The amplifier circuit also includes an amplifier having a differential input for amplifying differential input signals. A diagnostic test circuit is coupled between the balanced circuit and the amplifier circuit and includes a pair of resistors with current sources which may be switched in via electronic switches. With the current sources switched in, a known offset voltage is applied across the differential input to the amplifier and the amplifier output is monitored and compared to an initial output signal. By comparing the initial output signal with the test signal, a determination as to the gain and other characteristics of the amplifier circuit can be made.

Abstract: A power amplifier stage for producing a rectangular signal across a load, which may be predominantly capacitive, by means of a "bridge" amplifier comprises a first pair of transistors which operate alternately as an emitter follower and a second pair of transistors which alternately closes the circuit of the load. The four transistors of the bridge amplifier are respectively driven by identical four current sources in order to minimize the impedance of the circuit of the load for direct current. The transistors of the second pair are alternately connected as diodes. To control the signal amplitude, a generator supplies a control voltage whose value corresponds to a fixed component equal to 2.V.sub.BE, plus a variable component corresponding to the desired amplitude of the signal. Such a power amplifier stage can be used for driving a piezo-electric transducer, particularly for a telephone bell.

Abstract: A self-configurable, dual bridge, power amplifier has a window comparator sensing the level of input signals fed to the amplifier which-drives a plurality of configuring switches capable of configuring the amplifier as a single bridge amplifier driving a first and a second loads connected in series or as two distinct bridge amplifiers each driving one of the two loads. As long as the two levels of the input signals remain comprised between a range defined by a negative voltage reference and a positive voltage reference, the amplifier is configured as a single bridge driving the two loads in series, thus reducing sensibly power dissipation. Several embodiments of the configuring means are shown.

Abstract: An RF power amplifier is presented herein including an RF source for providing a train of RF pulses having a fixed frequency and wherein each pulse is of a fixed amplitude and duration. A bridge circuit includes a first circuit having a first transistor switching means for, when on, connecting a DC voltage source across a load for DC current flow therethrough in a first direction. The bridge circuit includes a second circuit including a second transistor switch for, when on, connecting the DC voltage source across the load for DC current flow therethrough in a second direction. A switch driver control serves, when enabled, to pass the RF pulses for driving the first and second transistor switches on and off at a frequency dependent upon that of the RF signal and in such a manner that current from the DC voltage source alternately flows in the first and second directions through the load.

Abstract: An apparatus for monitoring the temperature of an inaccessible portion of an electrical current carrying device that cannot be directly measured easily comprises circuits for establishing a reference temperature value in the vicinity of the current carrying device and measuring the power dissipated in the current carrying device, a digital computer having ports for inputting the reference temperature value, the power dissipated in the current carrying device, the thermal resistances and thermal time constants of the thermal model simulating the current carrying device to the reference temperature, and a program stored in the digital computer for continuously calculating a differential temperature based upon the power dissipation and thermal model and adding the reference temperature thereto.

Abstract: A differential amplifier circuit that exhibits low temperature drift and a wide dynamic range includes a differential amplifier having first and second input terminals, first and second circuit nodes operatively connected to the first and second input terminals, respectively, a differential input signal pair, first and second sampling capacitors and a switching circuit. During a first operational phase, the switching circuit connects, a first plate of the first capacitor to a first input signal of the differential input signal pair, connects a first plate of the second capacitor to a second input signal of the differential input signal pair, and connects second plates of the first and second capacitors to a reference voltage.

Abstract: Power amplifier for the feed of an inductive load having switched transistors is composed of a bridge circuit, wherein a plurality of series circuits of transistors with free running diodes are connected parallel in each bridge arm. An inductor is arranged in the connection of each series circuit to the inductive load, this inductor being current-compensated such that it has an effective inductance only when a non-uniform division of current occurs in a bridge arm. The transistors and diodes are linearly arranged.

Abstract: A composite bridge amplifier has four output transistors in a bridge configuration. The transistor control terminals (gates or bases) are controlled by an input signal which is amplified in a phase splitter and voltage gain stage. The output terminals of the transistors receive a power signal which varies with the input signal at a level sufficient to maintain headroom above the output signal but to reduce power dissipation in the transistors. The power signal is produced by a switch connected between a floating power supply and a filter and operated at e.g. 200 kHz. The switch is operated by a pulse width modulated (pwm) signal derived from the absolute value of the input signal. A proportional integral controller is coupled between the filter output and the pulse width modulator for closed loop feedback. The output is aligned with the input signal by a phase shifter connected to the controller. Since there is no time delay in the input signal (i.e. audio) path, high performance is achieved at reduced cost.

Abstract: A power amplifier circuit for an audio signal is provided with a switching control circuit and a switching circuit between an amplifier and a power source line or ground line and a smoothing circuit which smoothes current from the switching circuit and supplies the current to the amplifier, and the smoothing circuit is provided with a change-over switching circuit which operates to return a commutation current generated during switching OFF time to the smoothing circuit.

Abstract: The present invention includes a first amplifier, a second amplifier, a switching circuit for switching power from a power source line at a frequency exceeding an audible frequency and feeding the first or second amplifier, a control circuit for controlling a switching period of the switching circuit such that the feeding power is changed correspondingly to a level of the audio signal correspondingly to a first difference in voltage between one of the audio signal and the audio signal amplified by the amplifier and the power or a second difference in voltage between one of the audio signal and the audio signal amplified by the second amplifier and the feeding power, a smoothing circuit for smoothing a power fed by said switching circuit and a capacitor adapted to be charged by a portion of current flowing from said smoothing circuit when the switching circuit is in OFF state and generating discharge current to be added to the output of one of the first and second output stage amplifiers when the switching cir

Abstract: The present invention includes a first push-pull amplifier for amplifying an audio signal, a second push-pull amplifier for inverting and amplifying the audio signal, a switching circuit for switching power from a power source line at a frequency exceeding an audible frequency and feeding the first or second amplifier, a control circuit for controlling a switching period of the switching circuit such that the feeding power is changed correspondingly to a level of the audio signal correspondingly to a first difference in voltage between one of the audio signal and the audio signal amplified by the amplifier and the power or a second difference in voltage between one of the audio signal and the audio signal amplified by the second amplifier and the feeding power and a capacitor provided between the outputs of the first and second amplifiers, a loud speaker being driven by outputs of the first and second amplifiers.