Abstract: The invention relates to a method for extracting measuring signals from a multi-channel photomultiplier, characterised by the following steps: a measuring signal which is integral for the channels of the photomultiplier is extracted at the dynode in order to record the signal form and intensity of an event, and the anode signal of each channel is compared with a threshold value. If the threshold value is exceeded at a channel, the location of the detected event is determined and the associated signal form and intensity at the dynode is detected. The invention also relates to a circuit for a multi-channel photomultiplier (1), said circuit being used to carry out the method according to one of the claims 1 to 8. The circuit comprises a photocathode, a multi-channel structure for electron multiplication (dynode), and anodes (11) which are associated with the channels and are used for pixel-oriented charge amplification and collection.

Abstract: An optical signal receiver system provides for five (5) signals, namely VCC, Ground, RPM (Receiver input Power Monitor), Data, and Data Bar outputs, using only the four external pins of a conventional TO-style can package. To provide for five signals on only four pins, two of the output signals are superimposed on each other in which one has a DC value (RPM) and one has an AC value (Data or Data Bar). Once the combined signal comes out of the TO can, the combined signal can be separated into two separate signals using a capacitor which blocks the DC signal (Data or Data Bar) and allows the AC signal to go through. The DC information is then extracted by filtering the AC information from the combined signal with a Current Sense Circuit.

Abstract: An Improved Signal Receiver Having Wide Band Amplification Capability is disclosed. Also disclosed is a receiver that is able to receive and reliably amplify infrared and/or other wireless signals having frequency bandwidths in excess of 40 MHz. The receiver of the present invention reduces the signal-to-noise ratio of the received signal to ?th of the prior systems. The preferred receiver eliminates both the shunting resistor and the feedback resistor on the input end by amplifying the signal in current form. Furthermore, the receiver includes transconductance amplification means for amplifying the current signal without the need for Cascode stages. Finally, the receiver includes staged amplification to amplify the current signal in stages prior to converting the signal into a voltage output.

Abstract: An automatic-gain-control device in an optical receiver is provided and includes a pre-amplifier for converting a current signal outputted from an optical detector to a voltage signal and a bottom level detector for detecting the bottom level from the output of the pre-amplifier, the automatic-gain-control device comprising a bottom signal-level-determining section for analyzing the bottom level from the bottom level detector and outputting a signal denoting the presence of a signal and a reset signal for initialization at intervals between packets; and an automatic-gain-control signal generating section for providing an automatic-gain-control signal by showing the presence of a signal, the automatic-gain-control-signal-generating section including a first transistor which turns on according to a signal from the bottom signal-level-determining section and a second transistor which is connected to a capacitor for charging or discharging a voltage applied by the first transistor, and the drain voltage of which

Abstract: Optically isolated bias control circuit which provides bias current for switching circuits. Invention is amenable to high speed switching control with instantaneously variable pulse widths and duty cycles. Invention can be operated from DC upward in frequency, limited only by the characteristics of the implementing electrical components and electrical interconnections. Complementary embodiments of invention provide high speed operation with minimal electrical charge flow. Solar powered embodiments of invention may be used to control the switching of high power MOSFET-based switching circuits.

Abstract: Optically isolated bias control circuit which provides bias current for switching circuits. Invention is amenable to high speed switching control with instantaneously variable pulse widths and duty cycles. Invention can be operated from DC upward in frequency, limited only by the characteristics of the implementing electrical components and electrical interconnections. Complementary embodiments of invention provide high speed operation with minimal electrical charge flow. Solar powered embodiments of invention may be used to control the switching of high power MOSFET-based switching circuits.

Abstract: An optical receiver circuit including a plurality of PIN diodes, each associated with a dedicated element transimpedance amplifier, the outputs of the element transimpedance amplifiers being connected to a summing amplifier which sums the voltages output from the element transimpedance amplifiers. The optical receiver circuit provides the same output voltage value as a single large PIN diode having an active area comparable to the sum of the active areas of the smaller PIN diodes, and thus has the same high sensitivity as the single large PIN diode but a much wider bandwidth.

Abstract: Disclosed is a transimpendance amplifier comprising a single ended input terminal to receive an input signal from a photodiode and differential output terminals. A circuit coupled between the single ended input terminal and a differential output terminal may vary the gain of the transimpedance amplifier in response to a DC current component of the input signal.

Abstract: A transimpedance amplifier having a voltage amplifier and a feedback circuit coupled to an input terminal and an output terminal of the voltage amplifier. The feedback circuit includes an impedance element in parallel with a feedback resistive network. The feedback resistive network has a fixed effective resistance value. The feedback resistive network may have a first resistive element disposed between the input terminal of the voltage amplifier and a node, a second resistive element disposed between the output terminal of the voltage amplifier and the node, and a third resistive element disposed between the node and a ground terminal. Various systems utilizing a transimpedance amplifier consistent with the invention, including an optical communication system are also provided.

Abstract: A Class D switching audio amplifier incorporating four state modulation, input-to-output drive and feedback signal isolation, dual topology output filtration, and a low inductance board layout. The four state modulation results in a common mode voltage in the absence of audio. The input-to-output isolation of drive and feedback signals allows for elimination of large power transformers in applications without user-accessible outputs. Such isolation may make use of optical isolators. The output filter includes common mode and differential topology filter stages. The low inductance board layout treats the amplifier and power supply boards as modules, and utilizes both sides of the amplifier board in order to minimize trace length.

Abstract: A high-gain, high-speed differential preamplifier is described, in which a current source is coupled to one input of a differential amplifier and the other input of the differential amplifier is coupled to a sensor. In one implementation, the current source includes a field effect transistor operating in saturation mode and a bipolar junction transmitter in an emitter follower configuration.

Abstract: A digital power amplifier has a reduced size, high output, high efficiency and low power consumption. Electrical isolation is provided between input and output sections by a photo-coupler on a transmission passage for turning into a digital signal.

Abstract: An audio attenuator has a differential signal path with photoconductive cells connected to vary signal levels in the circuit. Electroluminescent light sources adjacent to the photoconductive cells direct light onto the photocells. The electroluminescent light sources receive the input audio signal, an output audio signal, or some other signal. The light sources are connected to a differential control with receives an input of the attenuator circuit. The differential control provides a control input to a differential audio amplifier which receives the input audio signal. The varying signal at the control input effects a variation in the gain of the amplifier. A compression or limiting of the input signal results, depending on which signal is connected to the light sources.

Abstract: An optoelectronic distance measuring device has at least one transmitter unit to transmit pulsed electromagnetic radiation, at least one receiver unit associated with the transmitter unit to receive the reflected radiation and an evaluation unit to determine at least the distance of objects reflecting the transmitted radiation, with a series connection of load resistors being connected after the receiver unit and a separate amplifier being associated with each load resistor to amplify the subsidiary pulse produced at the respective load resistor from an incoming, successively attenuated received pulse.

Abstract: A photoelectric receiver circuit for converting an optical signal to an electrical signal, includes first and second transimpedance amplifiers, a photodiode having a first end connected to an inverting input of the first transimpedance amplifier and a second end connected to an inverting input of the second transimpedance amplifier, and a differential amplifier having inputs AC coupled to outputs of the first and second transimpedance amplifiers. Such that when higher and lower voltages are respectively applied to the non-inverting inputs of the first and second transimpedance amplifiers, a substantially constant bias voltage is maintained on the photodiode.

Abstract: A tracking system and method in an optical communications system utilizing an optical communications beam. In one embodiment, the disclosed tracking system includes a tracking detector having a plurality of regions coupled to a corresponding plurality of tracking channel circuits. Each of the tracking channel circuits includes an optical detector coupled to receive the optical communications beam. The peak-to-peak amplitude modulation in the optical communications beam is measured by substantially reducing or removing a direct current (DC) offset present in the optical communications beam. In one embodiment, after the DC offset is substantially reduced or removed, the signal is then amplified and converted into an all positive signal, which is then filtered. The filtered signal is one of a plurality of tracking signal outputs, which are input to an alignment circuit.

Abstract: An audio attenuator has a differential signal path with photoconductive cells connected to vary signal levels in the circuit. Electroluminescent light sources adjacent to the photoconductive cells direct light onto the photocells. The electroluminescent light sources receive the input audio signal, an output audio signal, or some other signal. The light sources are connected to a differential control with receives an input of the attenuator circuit. The differential control provides a control input to a differential audio amplifier which receives the input audio signal. The varying signal at the control input effects a variation in the gain of the amplifier. A compression or limiting of the input signal results, depending on which signal is connected to the light sources.

Abstract: An automatic gain control circuit for an optical receiver couples the low level signal produced by an optical detector to a signal amplifier, preferably a double-ended differential amplifier with the optical detector output fed into the high input and the low input coupled to ground, the gain of which is controlled by a negative feedback circuit. The feedback circuit comprises a signal level detection circuit coupled to the amplifier output, such as high-speed Schottky diodes acting in conjunction with an operational amplifier. The Schottky diodes are coupled to ground through AC coupling capacitors, and oriented in opposite directions, so when the amplified signal exceeds a conduction threshold of the Schottky diodes the capacitors are respectively charged and drained, establishing a voltage difference between the input terminals of the operational amplifier.

Abstract: Described is a high voltage, high current operational amplifier in which galvanic separation of the input and output stages is achieved by means of an optical bridge, consisting of an LED and a photoresistor or phototransistor. The output stage utilizes two current sources, connected with inverse polarity and controlled by the optical bridge, thus allowing the transition between the low-voltage input stage and the high voltage output stage in a single step. Depending on the exact embodiment of the amplifier this invention can be customized to function with the properties of a Class A, B or C operational amplifier and can, in each of these embodiments, be used as an isolation amplifier.

Abstract: A Class D switching audio amplifier incorporating four state modulation, input-to-output drive and feedback signal isolation, dual topology output filtration, and a low inductance board layout. The four state modulation results in a common mode voltage in the absence of audio. The input-to-output isolation of drive and feedback signals allows for elimination of large power transformers in applications without user-accessible outputs. Such isolation may make use of optical isolators. The output filter includes common mode and differential topology filter stages. The low inductance board layout treats the amplifier and power supply boards as modules, and utilizes both sides of the amplifier board in order to minimize trace length.

Abstract: A subscriber-line terminal apparatus comprising an access control circuit for time-division multiple access to a plurality of subscriber-line terminating sets, a multi-channel array optical transmitter, and a multi-channel optical receiver, the receiver comprising a differential input amplifier, a first photoelectric converter element whose cathode is connected to a reverse-bias power supply and whose anode is connected to one input terminal of the differential input amplifier, and a second photoelectric converter element whose anode is connected to a reverse-bias power supply and whose cathode is connected to the other input terminal of the differential input amplifier.

Abstract: A light detection circuit employed in an electronic device such as an integrated circuit card is disclosed. The light detection circuit having a constant voltage supply connected to a power supply voltage, a sensing circuit including an element responsive to light and connected to the power supply voltage, a first comparator for determining a current sensing state according to an exposure to light, a latch circuit for storing the output of the first circuit, and a second comparator for generating an output signal which controls the constant voltage supply, the sensing circuit, and the latch circuit. The latch circuit outputs a light detection signal in response to the output of the second comparator.

Abstract: An object of the present invention is to provide an optical receiving circuit that it is possible to even a gain during a broad frequency band. The optical receiving circuit according to the present invention comprises an amplifier for feeding back negatively and amplifying an input signal, and a reflection coefficient setting circuit for setting an input reflection coefficient of the amplifier. For example, the reflection coefficient setting circuit has a resister Rin. One end of the resistor Rin is connected to an input terminal of the amplifier, and the other end of the resistor Rin is supplied with a voltage Vin substantially equal to a direct-current component of an input signal IN. The resistance of the resistor Rin is set so that the input reflection efficient becomes about less than about 0.3. Therefore, a peaking does not occur even at a resonance point, and it is possible to even a gain during a broad frequency band.

Abstract: A burst mode receiver using a multi-stage feedback reduces its pulse width distortion in output data and improves its sensitivity by exactly extracting a reference voltage used as a detection threshold based on a packet transmission for an optical multi-access network. The receiver comprises a differential preamplifier circuit for generating an output voltage after detecting a difference between a detected current input signal from photodetector and a reference input signal; current source for compensating an offset of the differential preamplifier circuit; multistage amplifier means for adjusting a voltage level of the reference signal to a half value of the output voltage of the differential preamplifier circuit; blocking transistor for responding to an output of the multistage amplifier means; capacitor for storing a peak amplitude of the detected current input signal; and buffer transistor for controlling a discharge rate of the capacitor.

Abstract: An amplifier (600) includes a first terminal (605) for receiving forward signals in a first frequency band and a second terminal (655) for receiving reverse signals in a second frequency band. A single gain block (630) is coupled between the first terminal (605) and the second terminal (655) for amplifying the forward signals and the reverse signals. The forward signals, after amplification, are provided to the second terminal (655) for transmission from the amplifier (600), and the reverse signals, after amplification, are provided to the first terminal (605) for transmission from the amplifier (600). In this manner, both forward and reverse signals, which are transmitted in separate frequency bands, can be amplified by a single gain block (630).

Abstract: An optical receiver generates a voltage signal having a predetermined swing from a current signal, and feeds the voltage signal to a decision circuit. An optical receiving element receives the input optical signal, converts the optical signal to a current signal, and provides the current signal to a preamplifier, which converts the input current signal into a voltage signal. The voltage signal is input to an amplifier having a limiting function, which linearly amplifies the voltage signal when the swing of the voltage signal is smaller than a predetermined value, and limitedly amplifies the voltage signal when the voltage signal is greater than the predetermined value. An automatic-gain-control amplifier receives the output from the amplifier with the limiting function, and amplifies the input voltage signal to a voltage signal having a constant swing.

Abstract: At least two innovations are used to overcome the limitations of conventional transimpedance or high impedance optical receiver front end amplifiers. The innovations are a) multiple stage equalization of a high-feedback resistor, low-gain transimpedance amplifier to obtain high sensitivity, and b) range switching of feedback resistors and equalization capacitors to obtain high overload. With these approaches, it is possible to design an optical receiver operating at the intrinsic limits of available device technology.

Abstract: An optical receiver having a photodiode and a preamplifier includes a charge controller which charges a capacitor depending on an received voltage signal at each burst timing of the burst-mode signal and then discharges the capacitor with a predetermined time constant to produce an amplitude-varying offset component. The current signal of the photodiode is controlled so that the amplitude-varying offset component is canceled out.

Abstract: Method for automatically controlling a controlled variable. In a feedback control process, a control loop is used to compare the controlled variable with a command variable that determines the setpoint of the controlled variable and minimizes a deviation between setpoint and actual value of the controlled variable with the help of a manipulated variable that acts on the controlled variable. A disadvantage of this process is the transient behavior of the control loop due to temperature influences and degradation phenomena. The method according to the invention is intended to prevent a change in the transient behavior of the control loop. In accordance with the invention, the loop gain (A) of the control loop (1) is regulated to a value at which the actual value of the controlled variable (x) overshoots the setpoint value (s) by a predetermined tolerance value (m) as the result of a pulse-shaped change in the command variable (w).

Abstract: A power amplifier having at least one switched output stage and a control unit for determining drive data for the at least one switched output stage, the control unit including an encoder for encoding the drive data in order to generate a data signal (DAT) according to a serial data transmission protocol, a data transmission link is provided for the transmission of the data signal, and a modulator is provided for generating switching signals for the switched output stage or stages dependent on the data signal. The structural outlay for the power amplifier thus is reduced, particularly in the case of a power amplifier having a number of output stages.

Abstract: A light receiving amplifying device includes a light receiving device for outputting a light signal current which varies with a quantity of received light, a load resistor connected with the light receiving device in series, for generating a detected voltage which varies with the light signal current, and a low frequency current bypass circuit for preventing the detected voltage from being saturated when the detected voltage has a frequency in a low frequency band. The low frequency current bypass circuit is connected with the load resistor in parallel and has an input impedance varying with a frequency of the detected voltage. The device further includes a transimpedance amplifying circuit (inverting amplifying circuit) for transforming an impedance of the detected voltage, and a capacitor for coupling the low frequency current bypass circuit and the transimpedance amplifying circuit (inverting amplifying circuit).

Abstract: A triggered optical receiver includes a single-ended or double-ended detector for detecting the optical signal and responsively transmitting a corresponding electrical signal to a first stage amplifier. The first stage amplifier output is transmitted to a triggered circuit having an input/output voltage hysteresis characteristic for identifying whether the amplified signal is a logic low or high. The hysteresis characteristic minimizes the effect of input noise and supply noise on the output. The width of the hysteresis loop may be selectively controlled to balance the sensitivity of the circuit against its noise tolerance characteristics.

Abstract: A large bandwidth analog isolation circuit is disclosed. Isolation transformers (11, 12) isolate the nonfloating side on the right hand from the floating side on the left hand. The input signal (1a, 1b) and a high frequency sinusoidal signal (3a, 3b) via a transformer (16) from an oscillator (18) are applied to a multiplier (20). The floating multiplied signal is supplied to a nonfloating multiplier (60). Thereby, the signal (6a, 6b) is multiplied by the high frequency sinusoidal signal (8a, 8b). The nonfloating multiplied signal (9a, 9b) is obtainable and is filtered (67, 68) to send out the output signal (2a, 2b) reproduced from the input signal (1a, 1b). Thus, replica of the input signal is obtained in the nonfloating side.

Abstract: Known is an optical receiver (4) in which first a received broadband optical signal is converted to a broadband electric signal by means of a optoelectric converter (49) comprising a transimpedance amplifier, and thereafter a channel is selected from the converted broadband signal by means of a tuner which is coupled to the transimpedance amplifier. Such a configuration is not optimal in fulfilling noise and bandwidth requirements. An optical receiver (4) for subcarrier multiplexed optical signals is proposed which has a tunable frequency selective front-end section (30) that is directly coupled to a photodiode (49) as an optoelectric converter so as to selectively pass a tuned channel from the received subcarrier multiplexed optical signal to a succeeding amplifier (36; 61).

Abstract: An automatic threshold control circuit includes a bottom detection circuit, a relative peak detection circuit, and a voltage divider circuit. The bottom detection circuit detects an absolute minimum level of an input signal, and the relative peak detection circuit detects, in accordance with the input signal, a maximum level relative to the minimum level detected by the absolute bottom detection circuit. Further, the voltage divider circuit generates a threshold level by dividing the absolute minimum level and the relative maximum level in a predetermined ratio. Using this configuration, a signal amplifying circuit can be constructed that is capable of accurately reproducing digital signals at all times regardless of variations in the amplitude or the DC level of the input signal.

Abstract: An optical signal is converted by a light-receiving element into a photoelectric current. The photoelectric current is converted by a preamplifier into a positive phase voltage and the opposite phase voltage. The peaks of the positive phase output and opposite phase output are sensed and held by a first and second peak sensing circuits. The median between the output of the second peak sensing circuit and the positive phase output of the preamplifier is determined by a first median output circuit. The median between the output of the first peak sensing circuit and the opposite phase output of the preamplifier is determined by a second median output circuit. A level comparison circuit compares the outputs of the first and second median output circuits and produces a signal voltage with a constant amplitude within a specific input voltage range, thereby producing a reception signal.

Abstract: The present invention provides an amplifier capable of accurately reproducing a signal under various operating environments and an optical receiving circuit using the amplifier. The differential amplifier is constructed such that the amplification factor thereof is set to 0.5, and a variation occurring inside thereof is the same as a variation occurring inside of the differential amplifier. Respective output variations occurring in maximum value holding circuits due to a temperature variation and a power supply voltage variation are canceled by providing differential amplification in the differential amplifier. At this time, an output variation occurring in the differential amplifier is also canceled. Therefore, an output variation occurring in the differential amplifier is made equal in value to the output variation occurring in the differential amplifier, such that the same variation as a signal input is superimposed on the reference input fed to the differential amplifier.

Abstract: A voltage isolation circuit having an improved method of combining the HF path and LF path is provided. The LF path comprises an opto-isolator to achieve voltage isolation of the input signal while passing low frequencies. The HF path comprises a transformer to achieve voltage isolation of the input signal while passing high frequencies. The HF path and LF path are combined at a summing node to obtain an isolated input signal. Obtaining a flat frequency response requires that the cross-over frequency between the LF path and HF path be closely matched. A portion of the LF path is injected into the HF path such that LF components are canceled out in the region of the transition frequency. In this way, the pole frequency of the transformer in the HF path may be compensated for to achieve a flat frequency response for the combined LF and HF paths.

Abstract: A photon coupled circuit comprises a high quantum efficiency semiconductor light emitter (TDA) coupled with low photon losses to a high quantum efficiency semiconductor light detector (OLD). Bias current is provided to both the light detector (OLD) and light emitter (TDA). The light output of the light emitter (TDA) is modulated by the signal current flowing therein and the current flowing (i.sub.o) in the detector (OLD) is modulated by the light received from the light emitter (TDA). The quantum transfer efficiency or open loop current gain is greater than 0.5 and a portion of the AC current flowing in the light detector (OLD) is applied as feedback to reinforce or oppose the current flowing in the light emitter (TDA).

Abstract: A method and apparatus for receiving infrared signals are provided. The circuit includes preamplifier that includes an integrator that charges based on light detected by a photodiode. The circuit includes a warning circuit that generates a warning flag when the charge on the integrator exceeds a predetermined level. To prevent the integrator from saturation, digital logic resets the preamplifier by dumping the charge on the integrator in response to the warning signal. The digital logic is also configured to reset the integrator at predetermined intervals. When the incoming signal is encoded using pulse position modulation, the interval at which the integrator is reset is the length of a single time slot in the pulse position modulation frame. A sample and hold circuit is provided to hold a previous output of the preamplifier. The difference between the previous output of the preamplifier and the current output of the preamplifier is compared with a threshold voltage to detect pulses on the incoming signal.

Abstract: An amplifier circuit (1) is arranged to amplify a signal of variable magnitude from a photodiode (3) having capacitive characteristics. The circuit (1) comprises a first feedback path containing a voltage controlled variable resistor (8) for varying the gain of the amplifier in relation to the magnitude of the signal so as to provide an output signal of substantially uniform magnitude. The first feedback path also contains a capacitor (7) which compensates for adverse effects of reactance in the circuit caused by the capacitance of the photodiode (3) and of the variable resistor (8) in order to optimize the frequency response characteristics of the amplifier. A second feedback path comprising a fixed value resistor (9) becomes operable when the resistance of the first feedback path is large to provide fixed gain amplification of signals received from the photodiode (3).

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: A method and apparatus for unambiguous, precise and self-calibrating detection of unreliable semiconductor operation is provided. The apparatus includes an optically coupled sensor positioned over a semiconductor device and an electrical feedback control loop for adjusting the operating range of the semiconductor device. The method includes the steps of measuring optical emissions from a semiconductor device and adjusting compensation circuitry connected to the semiconductor device in response to the measured emissions.

Abstract: A current boosted positive feedback logarithmic transresistance amplifier is provided for currency validators. The amplifier has a photo-diode capable of producing a current in response to light, connected to an operational amplifier having both a positive and a negative feedback branch. A logarithmic density amplifier having a feedback resistor and a log diode connected in shunt with the resistor as a dynamic feedback to the amplifier is connected to the positive feedback branch of the current boosting amplifier by way of the log diode. The summing action at the inputs of the current boosting amplifier result in a current at the log diode that is a direct multiple of the current in the photo-diode.

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 optical receiving apparatus of the present invention comprises an opto-electric conversion element for converting an optical signal into an electric signal, a differential type preamplifier for sending a non-inverting phase signal and a inverting phase signal of the electric signal and a first and second peak hold circuits for holding peak values of the respective non-inverting and inverting phase signals. Further, the optical receiving apparatus of the present invention comprises a first adder for adding the inverting phase signal to the non-inverting phase peak signal from the first peak hold circuit and a second adder for adding the non-inverting phase signal to the inverting phase peak signal from the second peak hold circuit.

Abstract: Transimpedance amplifier circuits and methods are provided in which the break frequency of the amplifier is adjusted through a single interface point to the amplifier circuit. At frequencies below the break frequency, the amplifier circuit provides an error current which effectively nulls the output of the transimpedance amplifier so that no output is produced. At frequencies above the break frequency, the break frequency setting element is essentially a short circuit that results in the frequency dependent voltage being substantially zero. This causes the transimpedance amplifier to convert current-to-voltage without signal degradation. The circuit also enables a user to adjust the break frequency without affecting the overall operation of the amplifier. Thus, the amplifier may be coupled to different output circuits for operations in accordance with different communication standards.

Abstract: A large dynamic range infrared receiver with a variable input resistance for use in optical communication systems is described. The variable resistance provides this infrared receiver with three ranges of sensitivity depending on the power of the optical signal incident on the receiver. At low optical power, the variable resistance is high, providing the infrared receiver with high sensitivity. For intermediate optical power the variable resistance is reduced, providing the infrared receiver with medium sensitivity. At high optical power levels, the variable resistance switches to a low value, reducing the infrared receiver's sensitivity and limiting the voltage across the variable resistance.

Abstract: An apparatus and method is provided that improves the dynamic range of an optical transimpedance receiver. The receiver includes a photodetector, a transimpedance front end amplifier and a non-liner feedback. The non-linear feedback means consists of a Schottky diode and shunting the transimpedance resistor with a parasitic capacitor. A lead compensation network is further included in the feedback circuitry to provide stability to the non-linear circuit by advancing the phase shifting of the transimpedance front end by 45 degrees. By stabilizing the frequency off the circuit, the dynamic range is increased from 26.6 dB to 40 dB.

Abstract: A tonal altering feature for a tube type guitar audio amplifier provides apparatus enabling selection of the type of phase inverter utilized.