Abstract: A programable gain amplifier (PGA) has an amplifier and a variable resistor that is connected to the output of the amplifier. The variable resistor includes a resistor that is connected to a reference voltage and multiple parallel taps that tap off the resistor. A two-stage switch network having fine stage switches and coarse stage switches connects the resistor taps to an output node of the PGA. The taps and corresponding fine stage switches are arranged into two or more groups, where each group has n-number of fine stage switches and corresponding taps. One terminal of each fine stage switch is connected to the corresponding resistor tap, and the other terminal is connected to an output terminal for the corresponding group. The coarse stage switches select from among the groups of fine stage switches, and connect to the output of the PGA.

Abstract: A reference circuit having a variable-impedance function for reducing current consumption is provided. By switching an output impedance of the reference circuit so that the output impedance is large when transmitting a high-frequency signal to a sensor coil, and the output impedance is small when receiving a response signal from the sensor coil, current consumption is reduced. The reference circuit includes a loop gain adjusting circuit having a switch for switching a gain. The magnitude of the output impedance of the reference circuit is switched by opening and closing the switch to switch the gain.

Abstract: A transimpedance amplifier system includes a first gain stage to receive an input signal. A second gain stage is coupled to the first gain stage to provide a first output. A first passive feedback element is coupled in parallel with the second gain stage. A general feedback element is coupled in parallel with the first gain stage and the second gain stage. A replica biasing stage is included to provide a second output. A replica feedback element is coupled in parallel with the replica biasing stage.

Abstract: In a preferred embodiment, a charge sensitive preamplifier for a radiation detector, including: an amplifier having a JFET input (stage) and a capacitive feedback element, the amplifier producing an output voltage (pulse) proportional to a charge (pulse) deposited at the JFET input by the radiation detector; and circuitry connected to the amplifier output and to a source node of the JFET to provide to the source node a pulsed reset signal.

Abstract: An amplifier includes a first broadband amplifier element (20) having a first and a second input (21 and 22, respectively) and also a first output (23). The first output (23) is fed back via a first and a second negative feedback path (30 and 40, respectively) to the first and second input (21 and 22, respectively). The first negative feedback path (30) includes a controlled current source (31), which brings about a reduction in the noise contribution of the second negative feedback path (40) and also a real finite input impedance.

Abstract: A front-end signal-processing device having an automatic gain-control function used in the analog-to-digital conversion. The circuit comprises a buffer circuit, an amplifying/attenuating circuit, a pre-processing gain-adjusting circuit and an amplification/attenuation gain-adjusting circuit. In the front-end signal-processing device having an automatic gain-control function used in the analog-to-digital conversion, a set of gain-adjusting signals S1 and S2 are produced by hardware for controlling the amplification or attenuation gain of signals, thereby automatically adjusting the amplitude of the input signals. In addition, the microprocessor can select an appropriate restoring parameter according to the gain-adjusting signals to ensure that the numeral result conforms to the original input signal.

Abstract: A variable gain amplifier comprises a main amplifier circuit whose gain is controllable and which amplifies a difference signal between an input signal and a feedback signal, a feedback amplifier circuit whose gain is controllable and which amplifies an output signal of the main amplifier circuit, and a gain control circuit which complementarily control the gain of the main amplifier circuit and the gain of the feedback amplifier circuit.

Abstract: A signal processing circuit using positive feedback while keeping the open loop gain of the circuit less than 1 to avoid oscillation. The circuit includes a floating signal source, a low gain amplifier, a feedback element, and a second stage circuit. The floating signal source produces a voltage that is impressed across the feedback element by the feedback system. The feedback element processes the voltage into an output current. The output current is passed through an output current node to the second stage circuit where the output current can be used as a current reference or be further processed. The output from the low gain amplifier may be used as a voltage output node that provides a voltage that is an amplification of the voltage produced by the floating signal source. The signal processing circuit may be embedded in another circuit, including additional stages of the signal processing circuit.

Abstract: Amplifier systems and methods are provided which closely approximate a constant output impedance and a constant quiescent output signal during forward and reverse modes of operation. The systems can be realized with small, inexpensive components that are compatible with integrated-circuit fabrication processes. A system embodiment includes a signal amplifier, a feedback path that is coupled across at least part of the signal amplifier to reduce its impedance, a reverse amplifier which is coupled to drive at least a feedback portion of the feedback path and a signal generator which controls operational timing of the signal amplifier and reverse amplifier. Another system embodiment includes an error-current canceler that cancels error currents of the signal amplifier with substantially equal and opposite correction currents.

Abstract: Summarizing, the present invention provides an IVC (100), comprising an operational amplifier (110) with an inverting input (112) and an output (113), and a feedback resistor ladder network (120) coupled between the output (113) and the inverting input (112). The feedback resistor ladder network (120) comprises a main chain (121) composed of a plurality of substantially identical unit resistors (RU) connected in series, and a plurality of branches (124i), each branch (124i) coupling a node (Xi) in the main chain (121) to the inverting input (112) of the operational amplifier (110), each branch (124i) comprising a selectable feedback switch (123i). Further, some of the branches (124i) comprise a non-unit resistor (RNUi) coupled in series with the corresponding selectable feedback switch (123i). Further, the present invention provides a circuit comprising a FIRDAC (20) and a bias block (30) for providing at least one bias current for the FIRDAC (20).

Abstract: A programmable gain amplifier (PGA) has an amplifier and a variable resistor that is connected to the output of the amplifier. The variable resistor includes a resistor that is connected to a reference voltage and multiple parallel taps that tap off the resistor. A two-stage switch network having fine stage switches and coarse stage switches connects the resistor taps to an output node of the PGA. The taps and corresponding fine stage switches are arranged into two or more groups, where each group has n-number of fine stage switches and corresponding taps. One terminal of each fine stage switch is connected to the corresponding resistor tap, and the other terminal is connected to an output terminal for the corresponding group. The coarse stage switches select from among the groups of fine stage switches, and connect to the output of the PGA.

Abstract: A signal processing circuit using positive feedback while keeping the open loop gain of the circuit less than 1 to avoid oscillation. The circuit includes a floating signal source, a low gain amplifier, a feedback element, and a second stage circuit. The floating signal source produces a voltage that is impressed across the feedback element by the feedback system. The feedback element processes the voltage into an output current. The output current is passed through an output current node to the second stage circuit where the output current can be used as a current reference or be further processed. The output from the low gain amplifier may be used as a voltage output node that provides a voltage that is an amplification of the voltage produced by the floating signal source. The signal processing circuit may be embedded in another circuit, including additional stages of the signal processing circuit.

Abstract: A signal processing circuit using positive feedback while keeping the open loop gain of the circuit less than 1 to avoid oscillation. The circuit includes a floating signal source, a low gain amplifier, a feedback element, and a second stage circuit. The floating signal source produces a voltage that is impressed across the feedback element by the feedback system. The feedback element processes the voltage into an output current. The output current is passed through an output current node to the second stage circuit where the output current can be used as a current reference or be further processed. The output from the low gain amplifier may be used as a voltage output node that provides a voltage that is an amplification of the voltage produced by the floating signal source. The signal processing circuit may be embedded in another circuit, including additional stages of the signal processing circuit.

Abstract: A semiconductor device comprises: a first resistor which has a plurality of first connection points to be selectively connected to an input terminal of an amplifier and has both ends to which a voltage is applied; and a second resistor which has one end to be connected to an output terminal of the amplifier and has a plurality of second connection points to be selectively connected to a feedback input terminal of the amplifier. One of the first connection points and one of the second connection points are selected in such a manner that a voltage at the output terminal of the amplifier becomes constant. Each of the first and second resistors is formed of first reference resistors having a first reference length and second reference resistors having a second reference length as many as needed, both of which are connected by an interconnect layer. The first and second reference resistors for forming the first and second resistors are provided in an effective resistor region and are regularly arranged.

Abstract: One embodiment of the present invention is an improved feedback amplifier circuit having a variable closed loop gain which avoids including switching elements in its feedback network and maintains a constant output voltage window for an input signal having a wide dynamic range. That is, the switching elements are not on the active feedback path (e.g., they are isolated from the active feedback path). In this manner, the gain of the amplifier circuit may be determined only by the feedback resistance which can be more easily controlled through the use of precision resistors. Additionally, by removing the switches from the feedback network, the parasitics associated with each switch may also be removed from the feedback path of the amplifier circuit. Accordingly, the bandwidth of the feedback amplifier circuit can be controlled more effectively. Specifically, the present embodiment avoids locating the switching functionality in the feedback network by changing the output stage of the feedback amplifier circuit.

Abstract: An apparatus comprising an amplifier circuit and a control circuit. The amplifier circuit may be configured to generate an amplified signal in response to an input signal. The control circuit generally comprises a differential amplifier having (i) a first input coupled to said amplified signal and (ii) a second input coupled to a reference voltage. The control circuit may be configured to control a dynamic range of the amplifier circuit by adjusting the input signal based on (i) a loop gain of the control circuit and (ii) the reference voltage.

Abstract: A multiplexing amplifier has a differential amplifier for amplifying multiple input signals which are selected by a plurality input select circuits. The select circuits are comprised of longtail transistor pairs which are activated by current steering diodes controlled by input selection signals.

Abstract: RF amplifier control circuits for transmitters in mobile communication devices, combinations thereof and methods therefor. The control circuits include generally proportional and integral control circuits having an output coupled to a control input of an amplifier. An initial control signal is applied to the amplifier before a vector modulator output coupled an input thereof is at full output power. The vector modulator output is ramped to full output after applying the initial control signal. Thereafter, the initial control signal applied to the amplifier during ramping is corrected by integrating an output of the amplifier relative to a second reference signal with an integral control circuit coupled to the control input of the amplifier, the second reference signal is proportional to the ramping vector modulator output.

Abstract: A transimpedance amplifier system includes a first gain stage to receive an input signal. A second gain stage is coupled to the first gain stage to provide a first output. A first passive feedback element is coupled in parallel with the second gain stage. A general feedback element is coupled in parallel with the first gain stage and the second gain stage. A replica biasing stage is included to provide a second output. A replica feedback element is coupled in parallel with the replica biasing stage.

Abstract: An amplifier is provided The amplifier includes an input voltage-to-current converter, a programmable input current divider, a current follower, a feedback voltage-to-current converter, and a programmable feedback current divider. The input voltage-to-current converter receives an input voltage and provides upper and lower input currents. The input current divider receives a first bias voltage and the upper and lower input currents, scales the upper and lower input currents, and provides upper and lower scaled input currents. The current follower receives the upper and lower scaled input currents, and provides upper and lower output currents and an output voltage. The feedback voltage-to-current converter receives the output voltage and provides upper and lower feedback currents. And the feedback current divider receives a second bias voltage and the upper and lower feedback currents, scales the upper and lower feedback currents, and provides upper and lower scaled feedback currents to the current follower.

Abstract: An RF variable gain amplifying device has an amplifying circuit, a switch element connected in parallel with the amplifying circuit, and a resistor connected in parallel with the amplifying circuit and with the switch element. The amplifying circuit does not operate when the switch element is in the ON state but operates when the switch element is in the OFF state. A potential at each of the input and output terminals of the switch element is lower when the switch element is in the ON state than when the switch element is in the OFF state.

Abstract: A data networking device having a variable gain amplifier with a first selectable impedance and a second selectable impedance for adjusting gain of the variable gain amplifier. The data networking device has an analog to digital converter for converting an analog output signal of the variable gain amplifier to a digital signal. The data networking device has a digital signal monitoring circuit for monitoring the digital signal and supplying feedback signals to actuate the first and second selectable impedances as a function of the digital signal, thereby adjusting the gain of the variable gain amplifier. A method of controlling a variable gain amplifier is also disclosed. An analog output signal of the variable gain amplifier is converted to a digital signal by an analog to digital converter. The method includes determining a portion of dynamic range of the analog to digital converter being used to convert the analog output signal of the variable gain amplifier.

Abstract: An apparatus (Z) having controllable impedance is inserted from output (22) to ground (23) of an audio-signal amplifier (20). Typically, the apparatus comprises a switch-chain (50) having multiple switches (52, 53, and so on); the first switch (52) is connected to one terminal (62) of the apparatus. A capacitor (82, 84, and so on) is connected from each switch to a second terminal (61). The network formed by the switch-chain (50) and the capacitor network (80) is called a matrix (60C). To bypass audio frequencies away from the chopping effect of the switches, an inductor (31) parallels the matrix. To prevent shorting of audio signals to ground, a larger capacitor (30) is in series with the inductor. An unstable voltage at output will see increasing capacitance as more switches are closed. The changing of capacitive impedance in relation to the amplitude of the unstable voltage is designed such that the unstable voltage cannot grow too large. More complex matrices further reduce voltage fluctuations.

Abstract: According to a level of an input signal, first switching means performs control in such a way that only a first feedback resistor or the first and second feedback resistors become feedback resistors connected to amplifying means, and thereby allows the amplifying means to keep linearity without saturating even when the level of the input signal changes. Furthermore, when the input signal has a higher level than a predetermined threshold, a phase compensation capacitor is charged under the control of second switching means for phase compensation of the amplifying means.

Abstract: An apparatus comprising an amplifier circuit and a control circuit. The amplifier circuit may be configured to generate an amplified signal in response to an input signal. The control circuit generally comprises a differential amplifier having (i) a first input coupled to said amplified signal and (ii) a second input coupled to a reference voltage. The control circuit may be configured to control a gain of the amplifier circuit by adjusting the input signal based on (i) a magnitude of the amplified signal and (ii) the reference voltage.

Abstract: An audio amplifier drives a load in the form of a sound producing loud speaker exhibiting a frequency variable impedance characteristic over a range of audio frequencies. Voltage and current feedback circuits respectively establish a minimum voltage feedback and a discrete feedback characteristic. A presence feedback circuit coupled to ground reduces feedback in discrete steps with increasing frequency above a selected level and a resonance feedback circuit coupled in parallel with the amplifier circuit coupled in parallel with the amplifier reduces voltage feedback in discrete steps with decreasing frequencies below a selected level. The controls are responsive to a digital interface for providing discrete settings.

Abstract: The invention relates to a device for amplifying electronic signals, including: an amplifier PRA, and a plurality of feedback loops G1, G2 placed between the output and the input of the amplifier, which feedback loops are arranged so that each feedback loop has an adjustable gain and all the feedback loops jointly form an assembly having an equivalent impedance which is substantially independent of the gain settings selected. Thanks to the invention, the amplification bandwidth can be easily adjusted without adversely affecting the performance of the device in terms of noise and high cut-off frequency.

Abstract: In a preamplifier for optical receivers, the input of an inverting amplifier is connected to an input terminal, the output of the inverting amplifier is connected to the gate of a first transistor, the source of the first transistor and the source of a second transistor are connected to a first bias member, the drain of the first transistor and the gate of the second transistor are connected to a first load member, the drain of the second transistor is connected to a second load member and an output terminal, and a feedback resistor is connected between the input and output terminals. With this configuration, a stable, low-power, wide-band transimpedance amplifier is provided without the necessity of special phase compensation.

Abstract: Provided is an amplifier circuit and method of using the same that features an adjustable resistor network to enable varying the operational characteristics of an amplifier. The resistor network includes primary resistors connected in series with a plurality of adjustment resistors connected to the output of an operational amplifier. A switching network is connected between the resistor network and the input of the operational amplifier. The switching network enables selectively varying the input and feedback resistance of the amplifier circuit to obtain a desired differential gain, while minimizing common-mode gain.

Abstract: According to a level of an input signal, first switching means performs control in such a way that only a first feedback resistor or the first and second feedback resistors become feedback resistors connected to amplifying means, and thereby allows the amplifying means to keep linearity without saturating even when the level of the input signal changes. Furthermore, when the input signal has a higher level than a predetermined threshold, a phase compensation capacitor is charged under the control of second switching means for phase compensation of the amplifying means.

Abstract: An audio amplifier drives a load in the form of a sound producing loud speaker exhibiting a frequency variable impedance characteristic over a range of audio frequencies. Voltage and current feedback circuits respectively establish a minimum voltage feedback and a discrete feedback characteristic. A presence feedback circuit coupled to ground reduces feedback in discrete steps with increasing frequency above a selected level and a resonance feedback circuit coupled in parallel with the amplifier circuit coupled in parallel with the amplifier reduces voltage feedback in discrete steps with decreasing frequencies below a selected level. The controls are responsive to a digital interface for providing discrete settings.

Abstract: An apparatus (Z) having controllable impedance is inserted from output (22) to ground (23) of an audio-signal amplifier(20). Typically, the apparatus comprises a diode-chain (50) having multiple steps (52, 53, and so on); its first step (52) is connected to one terminal (62) of the apparatus. A capacitor (82, 84, and so on) is connected from each step to a second terminal (61). The network formed by the diode-chain (50) and the capacitor network (80) is called a matrix (60C). To bypass audio frequencies away from the chopping effect of the diodes, an inductor (31) parallels the matrix. To prevent shorting of audio signals to ground, a larger capacitor (30) is in series with the inductor. An unstable voltage at output will see increasing capacitance as it gradually breaks over more and more diodes. The changing of capacitive impedance in relation to the amplitude of the unstable voltage is designed such that the unstable voltage cannot grow too large. More complex matrices further reduce voltage fluctuations.

Abstract: A non-inverting feedback amplifier with high disabled impedance includes a disableable signal amplifier; a feedback network having an input node, a feedback node and a reference node; the signal amplifier having a first input for receiving an input signal and a second input for receiving a feedback signal from the feedback node; and a reference buffer including a reference amplifier with its output directly connected to the reference node without additional series switching elements, a first input connected to a reference voltage, and a second input connected to its own output for mirroring at its output the reference voltage at its first input when the reference buffer and signal amplifier are enabled and presenting a high impedance between the feedback network and the reference voltage when the signal amplifier and reference buffer are disabled.

Abstract: A trans-impedance type preamplifier for an optical communication system with a high conversion gain and a wide band is provided, in which a preamplifier suppresses obvious peaking and has a flat gain characteristic over a high frequency range and a wide dynamic range. In the trans-impedance type preamplifier, the preamplifier includes an amplifier circuit, a feedback circuit, and a control circuit. The amplifier circuit includes a source grounded input FET for amplifing an electrical signal and a cascade-connected FET to which resistances are connected. Further, FET to which an output signal from the drain of the cascade-connected FET is input, a level shift diode, and an electrical current source FET are included therein. An output terminal is connected to the drain of the electrical current source FET.

Abstract: The present invention is directed to a circuit for performing volume expansion on an audio signal. The circuit includes an amplifier that has an input side and an output side. Further, the amplifier amplifies the audio signal at a first amplification to produce an amplified signal at the output side of the amplifier. The circuit also includes a shunting element coupled across the input side and output side of the amplifier. The shunting element includes a variable impedance device for changing the first amplification of the amplifier to a second amplification if the amplified signal reaches a predetermined threshold.

Abstract: A feedback type variable gain amplifier of the present invention is provided with a first inductor and a first field effect transistor connected in series across a power-supply potential terminal and a ground potential terminal, the one end of the first inductor connecting to the power-supply potential terminal, the one end of the first field effect transistor connecting to the ground potential terminal, the gate of the first field effect transistor being used as a signal input terminal, and the other end of the first field effect transistor being used as a signal output terminal, a second inductor, a second field effect transistor and a capacitor connected in series between the drain and the gate of the first field effect transistor, and, a resistor connected between the drain and the gate of said second field effect transistor.

Abstract: A first stage amplifier circuit includes an amplifier, a variable feedback resistance, a comparator and a shift register. The amplifier amplifies an input signal supplied thereto. The variable feedback resistance includes two or more feedback resistors and one or more switches for changing the connection of the feedback resistors and thereby changing the composite resistance of the feedback resistors. The variable feedback resistance is connected between the output terminal and the input terminal of the amplifier. The comparator judges whether or not the output signal of the amplifier exceeds a predetermined threshold value. The shift register has one or more stages corresponding to the switches of the variable feedback resistance. The shift register operates the switches of the variable feedback resistance one by one and successively reduces the composite resistance of the variable feedback resistance as long as the output signal of the amplifier is judged by the comparator to exceed the threshold value.

Abstract: There is disclosed a negative feedback amplifier provided with a feedback circuit used to make impedance variable and to improve high frequency characteristics and so configured to prevent a problem of parasitic capacity caused by a by-pass condenser. The feedback circuit connected in parallel to an inverting amplifier circuit is composed of a first feedback resistor connected in parallel to the inverting amplifier circuit, and a second feedback resistor and the by-pass condenser, both being connected in parallel to the first feedback resistor, and both ends of the by-pass condenser, together with the second feedback resistor, can be connected to the inverting amplifier circuit via first and second switching devices.

Abstract: A remotely controlled microphone amplifier has a first amplifier stage with a variable gain circuit operatively connected in the overall feedback loop of the first stage for controlling the gain in first increments. A unity gain second amplifier stage has variable attenuator operatively coupled between the output of the first amplifier stage and the input of the second amplifier stage. The variable attenuator controls the input to the second stage in second increments less than the first increments. The overall gain is linearly adjustable and varies in equal increments.

Abstract: In this invention an integrated operational amplifier is calibrated to optimize phase margin. The calibration is done to correct changes caused by operating temp and supply voltages as well as process variations and aging that can affect the stability of the amplifier. A calibration circuit measures the response of the operational amplifier to a pulse input and controls a feedback impedance to produce an optimized phase margin. The output response to the pulse input is measured at two different times, at a first time close to the transition capturing the peak overshoot from an under damped amplifier and at second time later than the first measurement when the distortions from the under damped ringing have diminished. A quantizer circuit compares the two measure voltages and provides an input to control logic which selects the amount of reactance in the feedback of the operational amplifier.

Abstract: The present invention is directed to a circuit for performing volume expansion on an audio signal. The circuit includes an amplifier that has an input side and an output side. Further, the amplifier amplifies the audio signal at a first amplification to produce an amplified signal at the output side of the amplifier. The circuit also includes a shunting element coupled across the input side and output side of the amplifier. The shunting element includes a variable impedance device for changing the first amplification of the amplifier to a second amplification if the amplified signal reaches a predetermined threshold.

Abstract: A differential amplifier provides a high common mode rejection while maintaining substantially unchanged the input dynamic range. The differential amplifier includes a comparator having inputs to which are applied the two input signals, which are also applied to an operational amplifier, so that the comparator outputs a signal whose sign is indicative of the sign of the difference between the two input signals. The output of the operational amplifier is feedback to one of the inputs of the operational amplifier through a current mirror. This feedback signal is switched between the non-inverting input of the operational amplifier and the inverting input of the operational amplifier. The switching of the feedback signal ensures negative feedback, and is dependent upon the sign of the difference detected by the comparator.

Abstract: An amplification circuit includes an amplifying unit to which a signal supplied via an AC coupling capacitor is input, the amplifying unit starting an amplifying operation for the input signal when a potential level at an input portion of the amplifying unit reaches an operating threshold level from a predetermined low level, and a feedback resistor circuit, provided in a feedback line through which electric charge is fed back to the input portion of the amplifying unit, in which feedback resistor circuit a resistance value is controllable by a control signal supplied from an outside thereof.

Abstract: A control signal amplification circuit for amplifying a control signal reproduced by a control head. The control signal amplification circuit includes a level detection circuit for detecting an output level of an amplification circuit body having an amplification factor determined on the basis of the quantity of negative feedback to thereby send out a level control signal indicating a result of the detection, and a variable feedback resistance circuit which is connected between a minus-input terminal and an output terminal of the amplification circuit body so that the equivalent resistance value of the variable feedback resistance circuit decreases when the level control signal indicates the increase of the output level, and the equivalent resistance value of the variable feedback resistance circuit increases when the level control signal indicates the decrease of the output level, whereby the control signal is amplified without deformation of its waveform.

Abstract: Two banks of differently-connected resistors are connected as an input to an op-amp feedback circuit.

Abstract: A transimpedance-type amplifier circuit includes a first resistor connected to a switching device and a second resistor connected with the first resistor in parallel with the switching device which is turned on in accordance with a result obtained by comparing an output from an inverting amplifier with a reference voltage. A diode is connected in parallel with the first resistor which is connected to the switching device, altering a feedback resistance constituted of these components. The diode maintains a terminal voltage across the first resistor to constant, and an optical current signal from a photodiode is therefore passed to discharge an electric charge accumulated in the parasitic capacitance of the photodiode.

Abstract: An operational amplifier includes an operational amplification means having a phase compensation capacitor, an active element connected in series to the phase compensation capacitor and having a variable resistance value, and a differential control means for changing the resistance value of the active element on the basis of a difference voltage between inputs to the operational amplification means, whereby stable operation and high-speed operation are realized.

Abstract: An instrumentation amplifier for absolute voltage amplification having a balanced voltage inlet and a balanced voltage outlet. The voltage inlet is coupled to first amplification units having a very high open-loop gain, and which is further coupled with a feedback network provided between the outputs and second inputs of the amplification units.

Abstract: A microwave circuit having a coupler with two microstrip conductors on a front surface of a substrate, parallel to each other, and electromagnetically coupled to each other with a coupling coefficient wherein the substrate has a rear surface on which a grounding conductor is formed. A floating conductor is interposed between the microstrip conductors. A first terminal of a switching device is connected to one end of the floating conductor while a second terminal of the switching device is grounded. By selectively turning on and off the switching device, the coupling coefficient is changed.

Abstract: A circuit assembly for an operational amplifier has an input stage with first and second input terminals and an output terminal. An output stage has a first input terminal coupled to the output terminal of the input stage, a second input terminal, and an output terminal. A feedback circuit is coupled between the output terminal of the output stage and the second input terminal of the input stage. An interconnection circuit is coupled to the first and second input terminals and the output terminal of the output stage and to a reference voltage source. The interconnection circuit has first, second, and third modes, such that the second input terminal of the output stage is coupled to the reference voltage source when the interconnection circuit is in the first mode.