Abstract: Transimpedance amplifier having an input stage (1) to which an input current to be amplified is fed and an output stage (2) which outputs an output voltage (uo) corresponding to the amplified input current. By means of a current control circuit (4) the current (Ic) flowing through the amplifying element (Q1) of the input stage (1) is detected and controlled in such a way that said current is independent of the ambient temperature and of the supply voltage (Vcc). To detect the current (Ic) a dummy transimpedance amplifier (5) is used in combination with a current mirror circuit (6), the current (Ic) being controlled in that the control voltage (Uc) of a further transistor (Qc) coupled to the amplifying element (Q1) configured as a transistor is adjusted accordingly.

Abstract: A polar modulator creates an amplitude signal and a frequency signal and digitally adjusts the signals so that the frequency and amplitude signals arrive at the power amplifier at the appropriate times. A digital predistortion filter is applied to the frequency signal. The frequency signal is then provided to a single port of a fractional N divider in a phase locked loop. The output of the phase locked loop drives an input of the power amplifier while the amplitude signal is converted to an analog signal and controls the power supply input of the power amplifier.

Abstract: A voltage buffer and follower includes a single ended output, a source follower, and a current feedback loop. The current feedback loop is coupled to the source follower and to the single ended output. When two voltage followers are used in a differential configuration, the voltage followers can become part of a high bandwidth gain cell. The high bandwidth gain cell includes a first and a second source follower circuit that are coupled to the first and the second current feedback loops, respectively. The first and the second source follower circuits are further coupled to a first and a second current mirror circuit, respectively. The first and second current mirror circuits are coupled to a load, which is coupled to a common-mode feedback circuit. The common-mode feedback circuit controls a constant current source that sinks mirrored direct currents that flow through the first and the second current mirror circuits.

Abstract: A compensated three stage amplifier having high gain as well as high speed is disclosed. The amplifier comprises a NMC and NGCC compensated cascaded three stage amplifier for receiving an input signal and for providing an amplified output signal in dependence thereupon. An extra feed forward transconductance stage extending from the input port of a first gain stage to the output port of a second gain stage of the amplifier is used in order to cancel one of two non-dominant poles in the transfer function of the amplifier with the additional zero introduced by the extra signal path. This results in a transfer function for a three stage cascaded amplifier having only two poles, which is highly desirable by allowing design of such amplifiers providing stable operation at high gain as well as high speed.

Abstract: A balancing circuit and method of operation thereof for use with a circuit having first and second complementary drivers exhibiting different current gain characteristics. In one embodiment, the balancing circuit includes a sensing subcircuit that provides a correction signal indicating a first current gain characteristic of the first driver. The balancing circuit also includes a compensation subcircuit that generates a current gain compensation signal to the first driver to substantially match a second current gain characteristic of the second driver based on the correction signal.

Abstract: Realizing a stabilized gain slope without increasing circuit scale or entailing extra time or care for correcting impedance. A resonant circuit that is made up of a capacitor and an inductor is provided in an output stage outside a feedback loop for realizing peaking at a particular frequency and for realizing a gain slope having a desired slope of, for example, 1 dB or more.

Abstract: The present invention is an apparatus and method to provide a high supply rejection and a full rail-to-rail output swing in an amplifier circuit. A first stage generates a first output. The first stage is powered by a second supply. A second stage is coupled to the first stage to generate an amplifier output. The second stage is powered by a first supply. The first and second supplies are different in regulation mode. By making the second supply a low noise supply, the power supply noise amplified by the first stage is minimized, with the voltage gain of the second stage regaining the rail-to-rail swing lost by the first stage due to the regulator supplying very low noise power to the first stage.

Abstract: Accuracy of correction of offset drift with temperature and noise are corrected in a high voltage, high current amplifier is improved by thermal isolation and/or temperature regulation of another amplifier having greater gain and connected to a different power supply in a closed loop feedback servo system. A clamping network connected to the higher gain amplifier to avoid hard saturation due to transient feedback signals from a reactive load, especially an inductive load, also prevents hard saturation of the high voltage, high current amplifier. An adjustable feedback circuit connected to the higher gain amplifier allows adjustment to obtain critical damping of a second order system and faster response to achieve proportionality of output current to input voltage with an accuracy of very few parts per million error and with minimum settling time.

Abstract: A cascode amplifier integrated circuit (IC) with a relatively fast transient fall response (i.e., short transient fall response time) and, therefore, relatively fast operation. The cascode amplifier IC includes a bias input terminal configured to receive a bias potential Vb, a power supply input terminal configured to receive a power supply voltage Vcc, an input signal terminal configured to receive an input voltage signal Vin, and an output signal terminal. The cascode amplifier IC also includes a gain stage circuit with a plurality of interconnected bipolar transistors and an output buffer stage circuit configured. The cascode amplifier integrated circuit further includes a discharge circuit configured to discharge stray capacitance at a node of the output buffer stage circuit.

Abstract: 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.

Abstract: A video signal distribution system comprises an interface device and video signal input means for receiving TV signals on broadcast channels connected to the interface device. A plurality of video appliances and a plurality of TV sets may be connected to the interface device such that the television sets are arranged to be remote from the plurality of video appliances. A person using the system has a remote control device that may be actuated to emit signals for selecting channels for viewing and to control the video appliances. Each of the television sets includes a repeater arranged to receive the control signals from the remote control device and form corresponding electrical control signals. The interface device receives the electrical control signals corresponding to a selected TV set and directs electrical control signals to a selected one of the plurality of video appliances to provide video signals to the television sets.

Abstract: A low noise amplifier for use in communications electronics includes first and second gain stages, switching circuitry that can switch the output of the first stage between the collector (common-emitter configuration) and the emitter (emitter-follower configuration) of the input transistor, thereby achieving high-gain or unity-gain, and an input-output path that can feed back a portion of the output signal to the input gain stage (high-gain mode) or couple a portion of the input signal directly to the output (low-gain mode) depending on the switch.

Abstract: A device having a broadband amplifier circuit is disclosed in which the amplifier circuit includes at least two field effect transistor stages with low transistors arranged as amplifiers and high transistors arranged as load transistors. The device has several stages where the output signal of a given stage other than the first stage is caused to be fed back to its own input through a feedback branch including at least the high transistor of the stage preceding the given stage.

Abstract: An information processing apparatus includes a plurality of processor boards arranged parallelly on the main board and the DC--DC converters for generating operation voltages for processor devices each disposed between the adjacent processor boards. Further, a metal plate with high thermal conductivity is placed in close contact with an area of each of the processor boards where devices generating a large amount of heat are mounted. Heat dissipating fins are joined to the surface of each of the metal plates so that when the processor boards are mounted on the main board, the heat dissipating fins do not contact the DC--DC converter. The heat dissipating fins and the DC--DC converters are arranged so that they are vertically disposed one over the other with respect to the main board.

Abstract: A plurality of field effect transistors (FET's) (11, 12) are coupled in cascode connection. A drain of the final-stage FET (12) is coupled to a gate of the first-stage FET (11) through a first negative-feedback circuit (13). A drain of the first-stage FET (11) is coupled to the gate of the first-stage FET (11) through a second negative-feedback circuit (14). The first negative-feedback circuit (13) is connected to a first resistor (Rf1) while the second negative-feedback circuit (14) is connected to a second resistor (Rf2).

Abstract: A wide bandwidth, multi-FET current sharing output stage, MOS audio power amplifier employs multiple feedback loops. An audio input is supplied to a voltage feedback amplifier stage driving a push-pull voltage gain/phase splitter stage. A bias adjustment stage driven from the push-pull voltage gain/phase splitter stage drives a current drive stage. The current drive stage drives an output stage comprising a plurality of paralleled current shared individual MOS output transistors driving an output node connected to a load. Up to three feedback loops are employed. A first voltage feedback loop comprises a voltage feedback stage having an input connected to a voltage divider driven from the first terminal of the load and an output connected to a feedback input node in the voltage feedback amplifier stage.

Abstract: An operational amplifier including reverse amplifiers interconnected in series in an odd number of stages not less than three, an element for feeding back an output from the reverse amplifier in the last stage to an input of the reverse amplifier in a first stage, and a feedback capacitance element provided across the input and output ends of at least one of the reverse amplifiers. The Miller effect makes the feedback current from the capacitance element appear as if it were increased by a factor of the amplification factor of a concerned inverter. Thus, the capacity of the capacitance element preventing the oscillation of the inverters can be reduced. As a result, the operational amplifier becomes highly responsive, and therefore, becomes operable for a high frequency signal.

Abstract: In this hybrid amplifier circuit the vacuum tube is direct coupled or DC coupled to the output of a solid state amplifier in a cathode follower configuration. An automatically operative bypass component, such as a Zener diode, LED, transistor junction or relay, diverts the signal output of the solid state amplifier around the vacuum tube stage when bias conditions or other vacuum tube operating conditions signify that the vacuum tube is still warming up or for some reason inoperative. Thus the hybrid circuit produces amplification at full volume and at low distortion even while the vacuum tube is warming up. The vacuum tube provides a desirable warming coloration to the sound that may be user adjusted by controlling the level of closed loop feedback within the circuit. Lower total harmonic distortion is achieved in a pentode vacuum tube device by direct coupling the screen and control grids. Lower voltage use of power pentodes wired in nonconventional "triode mode" is achieved.

Abstract: In a method and by an apparatus for correction of error signals and for forming of an arbitrary transfer function being independent of the quality of a payload (loudspeaker; H1) included in a signal amplification system, a control system (9) is used for supplying of the input signal to a basic amplifier (1) driving the payload. Said control unit includes a further amplifier (9) having an inverted input being supplied with a feedback signal from the output of the basic amplifier. In such a case the further amplifier involves only an inverted input, said input signal is supplied through one (4) of the resistors (3, 4) included in the feedback loop.

Abstract: A level shift amplifier has first to n th inverters connected in series, with each positive voltage terminal of the first to n th inverter is connected to the first source line. Each negative voltage terminal of the first to (n-2)th inverter is connected to output of the second next inverter, respectively. The negative voltage terminal of the (n-1)th inverter is connected to a part of the output of the n th inverter, and the negative voltage terminal of the n th inverter is connected to the second source line. n pieces of feedback elements are connected between the input and output of each inverter. When a feedback element is established so that the gain of each inverter can be maximized, a self-bias amplifier circuit is composed. All inverters are driven by the self-bias voltage. The fine amplitude signals input to the first inverter become the output voltage of full amplitude between the first and second source lines in the n-th inverter.

Abstract: A circuit for amplifying an input signal comprises an operational amplifi a dual operational amplifier, and a buffering operational amplifier all cascaded in the aforementioned order. The first operational amplifier amplifies the input signal with minimum noise degradation, is set up as a non-inverting amplifier stage, and has a local negative feedback loop comprising a resistor and capacitor in parallel. The dual operational amplifier has two amplifying devices. One device forms a second amplifying stage which increases the gain of the pre-amplified input signal and has a local negative feedback loop comprising a resistor. The other device is a third operational amplifier which combines with the buffering operational amplifier to form an amplifying and buffering stage. The third operational amplifier connects in series to the output of the second amplifying stage.

Abstract: A high gain RF amplifier comprises first and second common-emitter transistor amplifier stages coupled in cascade between an RF input terminal to which RF signals to be amplified are applied and an RF output terminal from which amplified RF signals are derived. A first RF signal feedback path is coupled between the emitter of the second common-emitter transistor amplifier stage and the RF input terminal. A directional coupler is connected to provide a second, high reverse isolation RF signal feedback path between the output terminal and the emitter of the first common-emitter transistor amplifier stage. The first RF signal feedback path preferably comprises a resistor-capacitor circuit coupled in series between the emitter of the second common-emitter transistor amplifier stage and the base of the first common-emitter transistor amplifier stage.

Abstract: An amplifier circuit including two general purpose operational amplifiers is disclosed. The output terminals of first and second operational amplifiers are connected via first and second resistors in series. A connection point between the first and second resistors is connected to an output terminal and is also connected to an inverting input terminal of the first operational amplifier via a feedback loop. Thus, the first and second operational amplifiers work as class-A amplifier, so that the crossover distortion is prevented from being generated. An input signal is inputted to a non-inverting input terminal of the first operational amplifier wherein the input signal is amplified. The amplified input signal is added with a dc bias voltage and is supplied to a non-inverting input terminal of the second operational amplifier. The output voltage of the first operational amplifier varies in a positive voltage area, and the output voltage of the second operational amplifier varies in a negative voltage area.

Abstract: An optical receiver comprises a plurality of sequentially-connected, symmetrically-constructed operational amplifiers having two complementary outputs. For the determination of the operating points and for suppressing the offset voltages, one output of each amplifier is connected by way of a negative feedback path to the second input of the first amplifier, whereas the useful signal is supplied to the first input of the first amplifier.

Abstract: An absolute-value analog-to-digital converter containing a chain of matched main absolute-value differential amplifiers (A.sub.1 -A.sub.N) has a gain control for regulating the gain of each main amplifier utilizing an auxiliary absolute-value differential amplifier (A.sub.GC) matched to the main amplifiers. An offset control in the converter drives the offsets of the amplifiers toward zero by using a further absolute-value differential amplifier (A.sub.OC) matched to the other amplifiers. The gain and offset control are implemented with suitable feedback circuitry.

Abstract: A coupling filter is formed from a plurality of four terminal networks. Each active four terminal network preferably has a bypass admittance, two filter admittances, a feedback admittance, and an amplifier. One end of the bypass admittance and of the filter admittances are connected to each other and to the input of the four terminal network, and one end of the feedback admittance is connected to the other end of the first filter admittance and to the input of the amplifier. The remaining ends of the second filter admittance and of the feedback admittance, as well as the output of the amplifier, are connected to each other and to the output of the four terminal network. Thus, except for the first four terminal network and the last four terminal network, the input of each four terminal network is connected by way of a coupling admittance to the output of the preceding four terminal network and said input is connected by way of a second coupling admittance to the output of the following four terminal network.

Abstract: A three-stage amplifier circuit specially configured to provide a high input impedance. An initial emitter follower transistor stage amplifies the current level of an ac input signal to produce a first intermediate signal, a common-base transistor stage amplifies the voltage level of the first intermediate signal to produce a second intermediate signal, and a final emitter-follower transistor stage amplifies the current level of the second intermediate signal to produce an output signal in phase with the input signal. A feedback circuit feeds back the output signal to the input of the common-base transistor stage, to supplement the first intermediate signal input. This effectively increases the input impedance of the common-base transistor stage and, likewise, the initial emitter follower transistor stage, whereby the amplifier circuit can be used to amplify signals produced by high impedance sources.

Abstract: By providing a current splitter stage and a feedback loop to current and voltage gain stages of an amplifier, a preamplifier can be implemented as an integrated circuit. This integrated preamplifier is particularly suited in bar code reader systems and fiber optic receiver systems.

Abstract: An active filter includes a first active stage including an operational amplifier and feedback means wherein the non-inverting input terminal of the operational amplifier is at a ground potential; a second active stage configured in the form of Miller integrator using an operational amplifier and connected in series with the first active stage; and means connecting the non-inverting terminal of the operational amplifier of the second active stage to the inverting terminal of the operational amplifier of the first active stage for enhancing the filter characteristics.

Abstract: A wide-band direct-current coupled transistor amplifier is provided which exhibits uniform gain in a frequency range from direct-current to greater than 100 MHz, and which exhibits other desirable features.

Abstract: A circuit for limiting transient intermodulation distortion in a amplifier system including an operational amplifier having a gain stage and a feedback network connected between the gain stage and the amplifier feedback port together with a pair of oppositely poled diodes, connected in parallel and coupled by means of capacitors between the amplifier output port and feedback port to limit the operational amplifier going to the supply rails under non-linear conditions thereby reducing the slew rate recovery time and therefore the amount of transient intermodulation distortion.

Abstract: A non-inverting amplifier circuit having input and output terminals wherein the input impedance between the input terminal and a reference point is relatively low. The circuit comprises a first amplifier having a non-inverting input coupled to the input terminal, an inverting input, and an output coupled to the output terminal. A second amplifier is also provided, the second amplifier having a non-inverting input, an inverting input coupled to the output of the first amplifier and an output coupled to the non-inverting input of the first amplifier.

Abstract: A feedback system for a multi-stage amplifier is disclosed which includes a nest of feedback loops centered on a particular stage, for example, on the output stage. This enables a very large amount of feedback to be applied to that stage, and enables constant return difference to be obtained for that stage over a nominated frequency range. Bode's limits for mid-band loop-gain magnitude and its rate of attenuation with frequency can be exceeded.

Abstract: Improved slew recovery in a composite driving amplifier for driving a substantially reactive load including a feedback loop to the operational amplifier from the load for regulating the output of the amplifier, the composite amplifier has a predetermined resistance R1 in the feedback loop and includes a second feedback loop having a predetermined resistance R2. The second feedback loop extends from the output of the operational amplifier to the negative input and is substantially parallel with the first-mentioned feedback loop. To maximize the recovery of the amplifier from a slew condition, the relationship of R1-R2 should be as follows: ##EQU1## wherein: V.sub.o is the output voltage in the amplifier.Slope, is the slope of the load voltage curve during the overload condition, andDelay represents the period of time it takes the overload operational amplifier to respond to a feedback signal at a given overload condition.

Abstract: A variable filter circuit, especially for synthesizing and shaping tone signals, in which a variable light source is provided which influences light sensitive resistor elements in the filter circuit. The variable circuit, by the use of selector switches, can provide different musical features, such as muted voices, percussion, brass, woodwind and the like, all of which will enhance, for example, existing organ voicing while it is, furthermore, possible to obtain the effect of playing a solo instrument together with organ voicing.

Abstract: A transconductance amplifier circuit including two operational amplifiers, as shown in the accompanying drawing, is disclosed. The gain of the amplifier circuit is determined by the resistances R1, R2, R3 and R4. The scale factor relating the output current i.sub.out to the input voltage e.sub.in is determined by the setting of the switches S1, S2, and S3, which adjust the amount of resistance between the output current terminal I.sub.o and the output terminal of the second operational amplifier A2. For R1/R2 = 1; R3/R4 = 1; and switch S1 closed i.sub.out = e.sub.in /R5. This transconductance amplifier circuit provides common mode rejection between the input voltage and the output current.

Abstract: An improved feedback/compensation scheme for a precision active rectifier circuit improves the slew rate and loop gain during diode switching and thereby reduces fractional scale linearity problems.

Abstract: An amplifier for processing television signals containing video information and related synchronizing components. An output feedback clamp circuit clamps a portion of the signal (e.g., the synchronizing components) to a point of reference potential and provides a D.C. voltage determined by the D.C. content of the video signal relative to the sync components. The amplifier is arranged to provide a predetermined D.C. gain (e.g., unity). The derived D.C. voltage is fed back to the amplifier input to reinsert a D.C. component which is processed through the amplifier in conjunction with the video signal and provides the necessary input to the clamp circuit.