Abstract: An output power detection circuit of a transmitter, which can accurately detect a power outputted from a power amplifier without depending on a change in ambient temperature is realized. The circuit comprises: a first diode to which a first bias direct current is applied; first load resistors through which the first bias direct current flows; a second diode to which a second bias direct current is applied; second load resistors through which the second bias direct current flows; and a differential amplifier. A first voltage generated in the first load resistor and a second voltage generated in the second load resistor are made substantially the same and are applied to the differential amplifier, a detection voltage obtained by detecting operation of the first diode is added to the first voltage, and a voltage corresponding to the power generated from a power amplifier is detected.

Abstract: A preamplifier is provided with a current feedback circuit including an amplifier for amplifying an input optical current and a feedback resistor connected between an input and an output of the amplifier, an average detecting circuit for detecting an average output voltage of the current feedback circuit and a current controlling circuit for distributing the input optical current in accordance with the detected average voltage. With this configuration, it is possible to generate an output voltage keeping an amplitude symmetry in a large voltage range.

Abstract: A reflective predistorter compensates for phase and amplitude variations imposed on an input signal by one or more non linear transfer characteristics of, for example, a power amplifier operating at or near saturation. The predistorter includes a hybrid having an input terminal, an output terminal and at least two relative phase terminals separated by 90 degrees. A first compensation circuit may be coupled to one of the relative phase terminals and may include a combination of linear and passive non-linear circuit elements. A second compensation circuit, identical to the first compensation circuit may be coupled to an other of the relative phase terminals includes a second combination of linear and passive non-linear circuit elements. The passive non-linear circuit elements may be one or more diodes and if more than one, the diodes are not configured as antiparallel. A first and second bias control circuit may be included for controlling a bias level in the first and second compensation circuit.

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: An amplifier stage in a series connection of such stages in a low or medium frequency analog amplifier construction, e.g. for audio, is provided with correction circuitry for dynamic cancellation of non-linearities in the stage output. The correction circuitry includes a threshold detector feeding a correction signal to an adder circuit that is inserted in the series connection. An input signal to the threshold detector is supplied from a junction where e.g. resistors coupled respectively to an input and an output of the stage, meet.

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: An amplifier/switch circuit includes a first circuit input, a second circuit input, a circuit output, an amplifier, a switching circuit and a DC blocking capacitor. The amplifier has an amplifier control input, a first amplifier output and a second amplifier output. The amplifier control input is connected to the first circuit input. The first amplifier output is connected to the second circuit input. The second amplifier output is connected to the circuit output. A switching circuit has a switch control input, a switch input and a switch output. The switch control input is connected to the circuit output. The control input is connected to the second circuit input. The DC blocking capacitor is connected between the amplifier control input of the first transistor and the switch input.

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 transimpedance stage amplifier converts a current input signal at an input node to a low impedance output voltage at an output node. The amplifier includes a resistor connected between the input node and the output node. A feedback loop is connected across the resistor, the feedback loop comprising a transistor, the transistor using the current input signal as a biasing current.

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: A transimpedance amplifier in an optical communication system is provided with automatic gain control (AGC) for increasing the input operating range while maintaining high stability. A photodetector is used to convert an optical signal into a differential current for the transimpedance amplifier. An AGC circuit has a gain control device connected across the differential input of the transimpedance amplifier. The gain control device has an impedance that varies as a function of a voltage at the differential output of the transimpedance. Preferably, the gain control device is a FET having a drain coupled to one of the differential inputs, a source coupled to the other differential input, and a gate for receiving an AGC voltage, the AGC voltage being a function of the voltage at the differential output.

Abstract: An inverting amplification circuit and a feedback resistor are connected in parallel with each other between an input terminal and an output terminal, so that an input current flowing from a photodiode can be converted into an output voltage. Furthermore, a shunt transistor is disposed with its source connected with the input terminal, its gate connected with the output terminal and its drain connected with a ground power supply. When the input current is large, a current flowing into the feedback resistor is decreased, so that a part of the input current can be shunted by the shunt transistor in accordance with a voltage difference between the input terminal and the output terminal. Thus, the output voltage waveform can be free from ringing.

Abstract: An optical receiver preamplifier provides a transimpedance feedback path between the output node and the input node that comprises a feedback resister and the two diodes are coupled ("paralleled") in opposite direction. While the input current signal is too large, and the voltage reach the diode's threshold voltage. The preamplifier can provide current path passing the signal to solve the problem that charge-discharge time is not uniform and changed over duty-cycle. Further, the two diodes are coupled ("paralleled") in opposite direction make photo-diode working under the large-signal current by anode or cathode input. Thus, increase the dynamic range of the transimpedance preamplifier. Besides, the low impedance of series resistance connects with input node and feedback network. The influence of bandwidth and stability that the aforementioned two paralleled diodes resulted in diode junction capacitor will reduce due to the low impedance of series resistance.

Abstract: A feedback amplifier includes an input terminal where an input voltage is detected from an input current; an amplifier circuit which amplifies the input voltage to generate an output signal; a first output terminal from which the output signal is outputted; and a feedback circuit. The feedback circuit includes a feedback resistor connected between the input terminal and the first output terminal; and a diode which connected in parallel to the feedback resistor. The output signal is feedback-controlled in response to the product of the input current and the impedance of the feedback circuit.

Abstract: A feedback circuit for use with a power amplifier is disclosed. A feedback circuit includes means for providing An inactive state wherein the input for the feedback circuit comprises an output of the loop filter operational amplifier and an active state wherein the input for the feedback circuit consists of a coupled, demodulated power amplifier output. A soft switching circuit is included for gradually switching between the inactive and active states, such that transient spikes are prevented within the feedback circuitry signal.

Abstract: An amplifier circuit with improved turn-on and turn-off transient operation includes a differential amplifier and a selectively variable reference generator for controlling the amplifier output during circuit turn-on. The amplifier has differential inputs which are driven by a reference voltage from the reference generator and a single-ended input signal. During circuit turn-on, the selectively variable reference voltage, generated by charging the bypass capacitor with a constant current source, charges in a linear manner from ground potential toward its final value of, typically, half of the power supply voltage. During circuit turn-off, the bypass capacitor is discharged with a constant current source in a linear manner toward ground potential. This allows improved turn-on and turn-off transient operation to be realized, e.g.

Abstract: Non-linearity of a voltage-controlled non-linear amplifier/attenuator is compensated by placing a non-linear circuit in the feedback path of an operation amplifier of a linearizer, the circuit including one or more differential amplifiers connected in parallel. For example, one amplifier can be a low-gain amplifier whose exponential range is at the lower end of the control voltage range, and another can be a high-gain amplifier whose exponential range is at the upper end of the control voltage range. When a necessary number of differential amplifiers are used in the feedback path, it is possible to compensate for the non-linearity of the non-linear component to a desired extent.

Abstract: A negative feedback preamplifier having variable conversion gain control and variable open loop gain control capabilities which can work correctly regardless of semiconductor process variations. The negative feedback preamplifier used to convert an input signal current to a signal in the form of voltage includes: a resistor which determines the current-voltage conversion gain when a small signal current is input to the negative feedback preamplifier; a diode which switches the current-voltage conversion gain when a large signal current is input to the negative feedback preamplifier; a resistor which determines the current-voltage conversion gain when the large signal current is input; a grounded source amplifier including a main FET which is biased such that its transconductance decreases when the large signal current is input; and a bias setting portion (diode) which determines the bias condition associated with the main FET.

Abstract: A detector for a portable telephone or the like samples RF transmit power, detects the sampled signal using a Schottky diode and uses a logarithmic amplifier to apply a compressive function to the post-detection signal. The compressive function emphasizes power level changes at the low end of the transmission spectrum and de-emphasizes power level changes at the high end of the transmission spectrum. In this way, the range of detected powers required to be processed by subsequent circuitry is reduced, thereby simplifying the design of the circuit. To improve stability of the detector with respect to temperature fluctuations, the semiconductor element in the amplifier which provides its logarithmic characteristics is temperature-compensated, as is the detector diode.

Abstract: A signal processing circuit is provided which includes a frequency selective network in a feedback loop for noise shaping purposes. A sampling analog-to-digital converter in the feedback loop operates at a sample frequency substantially above the Nyquist frequency. A switching device is driven by the sampling analog-to-digital converter and produces a continuous-time output signal which is continuously monitored by and fed back to the frequency selective network for noise and distortion correction in the feedback loop. This is in contrast to traditional techniques which employ only state feedback. State feedback (i.e., digital or sampled) of the output of the analog-to-digital converter may also be employed in combination with the continuous-time feedback of the switching device output.

Abstract: An integrator circuit (10) and a method for generating an output signal that is frequency compensated. The integrated circuit (10) includes an input stage (14) coupled to a transconductance amplifier (11) via a capacitor (13) and a compensation diode (12). The compensation diode (12) provides an impedance that negates an output impedance of the transconductance amplifier (11). The output signal of the integrator circuit (10) is determined by the capacitor (13).

Abstract: A limiting transimpedance amplifier includes an amplifier stage including a feedback resistor, a limiting diode coupled across the feedback resistor, and a stabilization diode coupled to the amplifier stage to compensate for feedback instability introduced by the limiting diode. The amplifier stage includes an input transistor and an output transistor, where the feedback resistor couples an output of the output transistor to an input of an input transistor. A stabilization voltage generator is coupled to the stabilization diode to provide a stabilization voltage that causes the desired compensation.

Abstract: An amplifier circuit with improved turn-on transient operation includes a differential amplifier and a selectively variable reference generator for controlling the amplifier output during circuit turn-on. The amplifier is biased by a single power supply and its differential inputs are driven by a reference voltage from the reference generator and a single-ended input signal. Following circuit turn-on, the selectively variable reference voltage, generated by charging the bypass capacitor with a constant current source, charges in a linear manner from ground potential toward its final value of, typically, half of the power supply voltage. This allows improved turn-on transient operation to be realized, e.g. reduced "pops" and "clicks" upon circuit turn-on, while giving the user increased flexibility in selecting the sizes of the reference voltage bypass capacitor and the input signal coupling capacitor.

Abstract: Photocurrents outputted by photo detecting circuits (1.sub.1 to 1.sub.n) disposed in first current paths (2.sub.1 to 2.sub.n) are amplified by current amplifying means (3.sub.1 to 3.sub.n) disposed in the first current paths (2.sub.1 to 2.sub.n), respectively. The output currents from the plurality of current amplifying means (3.sub.1 to 3.sub.n) are converted into voltage all by one current-voltage converting means (5). The current amplifying means (3.sub.1 to 3.sub.n) are turned on or off by control signals (3.sub.1S to 3.sub.nS), and therefore the luminance detecting circuit amplifies the current of the required photo detecting element only, and outputs into the current-voltage converting means (5).

Abstract: Automatic Gain Transimpedance Amplifiers for analog applications having high bandwidth, wide dynamic range, and ultra-high linearity. The transimpedance amplifiers includes an operational amplifier and a variable feedback resistance means connected between the input and the output of the amplifier. The variable feedback resistance means may include a single feedback PIN diode, two serially connected feedback PIN didoes, a PIN diode connected to a feedback resistor in parallel, or two serially connected PIN diodes connected to a feedback resistor in parallel. Ultra-high linearity is achieved because the dynamic resistance of the PIN diode under forward bias is substantially linearly dependent on the inverse of the current that passes the diode.

Abstract: An amplifier circuit with improved turn-on and turn-off transient operation includes an amplifier and a controller for controlling the amplifier output during initial and subsequent circuit turn-on and turn-off. The amplifier is biased by a positive power supply voltage and has a differential input driven by a reference voltage and a single-ended input signal. Where the output is single-ended, a single amplifier provides a single-ended output signal. Where the output is differential, the amplifier includes cascaded, differential input, single-ended output amplifiers which together provide a differential output signal. Following circuit turn-on and turn-off, the reference voltage, which drives one of each of the differential inputs, typically charges to or discharges from, respectively, a value of half of the positive power supply voltage.

Abstract: A transimpedance amplifier circuit includes an inverting voltage amplifier having an input being supplied with an input current and an output carrying an output voltage. A coupling member is connected between the input and the output of the voltage amplifier. The coupling member has two diodes being connected antiserially to one another between the input and the output of the voltage amplifier with a common node point. A transistor has a load path being connected between the common node point and a ground potential. A differential amplifier has one input connected to the input of the voltage amplifier, another input connected to the output of the voltage amplifier, and an output. A low-pass filter is connected downstream of the differential amplifier for furnishing a trigger signal at the output to the transistor.

Abstract: An electronic circuit incorporating an operational amplifier and a feedback network consisting substantially of a plurality, N+M, of substantially identical non-linear elements connected in parallel in two groups of N and M elements each to provide a linear feedback stabilized gain or attenuation.

Abstract: The apparatus includes output stage amplifiers for receiving the respective outputs of preamplifiers provided in correspondence to the left and right channels in a stereo system. Negative feedback circuits are provided in the respective output stage amplifiers for reducing the amount of low-band negative feedback. Switch circuits are turned on in response to feedback signals from the respective negative feedback circuits for supplying the feedback signals at the input to the output stage amplifiers.

Abstract: A transimpedance amplifier has an amplifier unit, a feedback resistor arranged between the output and input ends of the amplifier unit, a voltage clamp unit connected to the opposite ends of the feedback resistor, to clamp a voltage applied to the ends of the feedback resistor and prevent the amplifier unit from saturating, a current absorption unit arranged on the input side of the amplifier unit, to absorb any large input current supplied to the amplifier unit, and a switching selection unit to activate or deactivate the current absorption unit according to an external control signal. The current absorption unit is activated through the switching selection unit when a large input current is produced to write data to a magneto-optic disk in a magneto-optic disk unit in which the transimpedance amplifier is installed.

Abstract: An automatic transimpedance control amplifier is disclosed. The amplifier incorporates an automatic gain control circuit which simultaneously and automatically adjust the value of transimpedance and the voltage gain at each gain stage of the amplifier according to the input current. The amplifier has wide bandwidth, high sensitivity/and more importantly, wide dynamic range.

Abstract: A photocurrent detector circuit includes a photodiode coupled to an input terminal of a first operational amplifier. A first resistor has a first end coupled to the photodiode and a second end coupled to an output terminal of the first operational amplifier. A first diode has a first end coupled to the photodiode. A second resistor has a first end coupled to a second end of the first diode. A low gain bias network is coupled between a second end of the second resistor and the output terminal of the first operational amplifier. A second diode has a first end coupled to the photodiode. A clamp bias network is coupled between a second end of the second diode and the output terminal of the first operational amplifier. Preferably, the photodiode and the first and second diodes include silicon carbide. The detector may further include second and third operational amplifiers coupled to the output terminal of the first operational amplifier.

Abstract: Disclosed is a low distortion amplifier circuit of the predistortion type that employs a cuber circuit in the predistortion path to provide optimized signal energy at third order intermodulation frequencies, which cancels IMD products generated by the main power amplifier. The cuber circuit employs a pair of anti-parallel diodes that are biased with at least one D.C. source to produce a D.C. current flow through each diode. The input signal applied to the cuber circuit produces signal current flow in each diode to enable a third order output current to be extracted. A desired amount of third order power is thereby provided to realize minimal IMD power in the main amplifier output over a wide dynamic range of the input signal.

Abstract: A linear amplifier (103) has a negative feedback loop that has a closed loop gain and a forward path gain. The negative feedback loop is closed, such that quick changes in the closed loop gain are prevented, thereby reducing splatter. When the negative feedback loop is opened, quick changes in the closed loop gain are also prevented, thereby reducing splatter.

Abstract: An RF signal amplifier comprising a single stage of amplification coupled through a first switch to the input of a SAW delay line and, after the SAW delay line is charged, through a second switch to the input RF amplifier for second amplification with the output of the RF amplifier being coupled through said first switch to an output terminal.

Abstract: A transimpedance amplifier circuit for converting an input current to an output voltage includes a feedback resistor variable circuit which is connected in parallel to a feedback resistor and a load resistor variable circuit which is connected to a collector of an amplifying transistor. The feedback resistor variable circuit includes a first resistor and a first P-N junction diode connected in series. After the first P-N junction diode turns on in accordance with the increase in the input current, the transimpedance is decreased. As a result, a wide input dynamic range can be achieved. The load resistor variable circuit includes a reference voltage source and a series circuit of a second P-N junction diode and a second resistor. After the second P-N junction diode turns on in accordance with the increase in the input current, an effective load resistance value of the amplifying transistor is decreased, whereby the gain of the amplification transistor is decreased.

Abstract: An improved method and circuitry for processing high-impedance (current mode) input signals for use in translinear and other mode circuits in a manner that avoids the signal dependent bandwidth variations that occur in the prior art. A non-linear feedback structure using a transconductance gain element is employed to extend the bandwidth and/or suppress bandwidth variations encountered in the prior art. One application of this invention is the extension of Gilbert amplifier topologies, with their attendant normalization and integrated circuit implementation advantages, for operation with very low input signal levels to high bandwidth applications. A further extension in this invention allow this transconductance to be electrically adjusted to allow active bandwidth control or to compensate for signal sources with different input capacitances. The invention is particularly suitable for use as a preamplifier for pairs of sensed photodetector current signals.

Abstract: A variable gain voltage signal amplifier is provided for incorporation in an automatic gain control circuit, such as for a disk drive. The variable gain voltage signal amplifier comprises: an amplifier including an inverting input voltage signal terminal and an output voltage signal terminal. The amplifier includes an input signal path coupled to the input voltage signal terminal and further includes a feedback signal path coupling between the input voltage signal terminal and the output voltage signal terminal. The input signal path comprises a capacitor coupled in series with a resistor, and the feedback signal path comprises a resistor. At least one of the resistors comprises an electronic signal-controlled resistor.

Abstract: A feedback network for linear operational amplifiers comprising n+1 identical non-linear devices which nonetheless yield a linear gain.

Abstract: A power factor control system for an A.C. induction motor determines the difference in phase between the voltage applied to the motor and the current drawn by the motor. Based upon this difference in phase, an integrator generates an error signal. The error signal is compared with a ramp wave to derive a pulse signal which controls the voltage applied to the motor, which in turn controls the amount of current supplied to the motor, in order to reduce the power consumed by the motor. The integrator includes a dual-path feedback filter having a polarized capacitor in each path. A power supply is used to quickly provide the full operating bias voltages required by several of the components contained in the control system.

Abstract: Optical receivers with a photodiode (PD) and a transimpedance amplifier are optimized for signals with a particular transmission rate. A circuit is provided whereby the optical receiver can be adapted to different transmission rates. To attain this object, the feedback resistor of the transimpedance amplifier is divided into at least two resistors (R.sub.F1, R.sub.F2) connected in series. According to the transmission rate, the respective optimum resistance value is switched into the negative-feedback path with the aid of a control circuit. This makes it possible to operate such a universal optical receiver in a broadband subscriber interface both at a transmission rate of 150 Mb/s and at a transmission rate of 600 Mb/s, for example.

Abstract: A power amplifier apparatus having an operational amplifier which works as a PWM (pulse width modulation) amplifier as well as an analog amplifier according to an input signal level to miniaturize the size of the apparatus and to maintain amplifying function thereof at the changeover of the function, which allows gain and frequency characteristic of the operational amplifier to have continuity before and after the changeover.

Abstract: A preamplifier converting an input current signal into an output voltage signal and outputting the voltage signal includes a voltage amplifier, a feedback resistor connected in parallel with the voltage amplifier, and a plurality of diodes connected in series to each other and in parallel with the feedback resistor. In this circuit, the voltage drop of the feedback resistor for turning on the diodes increases in proportion to the number of diodes, thereby changing the input signal level at which the feedback resistance switches. A fuse may be connected in parallel with each of the diodes, a bonding pad may be connected to each of them, or an FET may be connected in parallel with each them to enable short-circuiting of each of the diodes. Thereby, an increased dynamic input range is obtained while giving consideration to the sensitivity and the amplification factor of the amplifier.

Abstract: An optical power monitoring circuit in an optical data receiver. A transconductance amplifier with non-linear feedback converts averaged photodiode current into a voltage representing a logarithm of the received optical power, which may be converted into decibels referenced to a standard power (dBm). The circuit has wide dynamic range and uses matched devices to provide processing and temperature compensation.

Abstract: The method and apparatus of the invention effects compression of an analog electrical signal (e.g., representing an interferogram) by introducing into it a component that is a cubic function thereof, normally as a nonlinear negative signal in a feedback loop of an Op Amp. The compressed signal will most desirably be digitized and then digitally decompressed so as to produce a signal that emulates the original.

Abstract: A plurality of integrating photosensors is disposed in an array of rows and columns, with a given row select line connected to the gates of P-channel MOS transistors associated with that given row and a given column sense line connected to the drains of the P-channel MOS transistors associated with that given column. A sense amplifier is associated with each column. An integrating sense amplifier according to the present invention includes an amplifying element having an inverting input and a non-inverting input. The non-inverting input is connected to a source of reference voltage the inverting input is connected to a sense line. A P-channel balance transistor is connected between the inverting input and the output of the amplifying element and a capacitor is also connected between the inverting input and output of the amplifying element. A capacitor, preferably a varactor element, is connected between the output and the inverting input of the amplifying element.

Abstract: A MOSFET whose back gate area is independent of a substrate is employed as a level-slicing transistor which is simultaneously used for alternately turning ON and turning OFF four analog switches in accordance with the relation between the voltages of the output terminal and inverted input voltage of the output terminal is limited to V.sub.B .+-.V.sub.th, where V.sub.th is the amplitude at the threshold level of the levelslicing transistor and V.sub.B is the bias voltage.

Abstract: A preamplifier for audio frequecy electrical signals generated by a musical instrument such a guitar having distortion characteristics simulating those of a vacuum tube amplifier. A solid state amplifier has an input for receiving electrical signals generated by the musical instrument and has an output for providing an output signal. Circuitry asymmetrically clips the output signal to provide as the output signal a nonlinear asymmetrically clipped signal having harmonic content which varies as a function of the amplitude and duration of the received electrical signals. The clipped signal has musically desirable harmonic overtones and produces different tonal responses simulating the characteristics of an overdriven vacuum tube amplifier.

Abstract: A transimpedance amplifier comprises a transconductance amplifier having a nonlinear resistive feedback element. The feedback element includes a pair of resistors and a pair of diodes, one of which conducts (depending upon the voltage polarity) only when the voltage across the diode exceeds the diode on-voltage. This includes additional resistance in the feedback element thereby changing the amplifier gain. The largest value of the resistive feedback element is substantially equal to or less than the output resistance of the transconductance amplifier. The feedback element is both symmetrical and nonlinear. A shunt amplifier is driven by circuit which produces a control signal that varies with a signal current. Increasing signal current increases the DC current shunted from the amplifier input thus decreasing pulse edge distortion and increasing dynamic range. A capacitor AC couples the current input to the amplifier.