Showing papers on "Transimpedance amplifier published in 1985"
TL;DR: In this paper, the design of a high-performance single-mode optical time-domain reflectometer (OTDR) is discussed, which uses a low-noise receiver with a p-i-n diode detector and transimpedance amplifier together with multichannel digital averaging.
Abstract: The design of a high-performance single-mode optical time-domain reflectometer (OTDR) is discussed. The approach uses a low-noise receiver with a p-i-n diode detector and transimpedance amplifier together with multichannel digital averaging. A dynamic range of 30 dB one way at 1.3 μm is demonstrated with a laser diode source, and with a Nd:YAG laser source the dynamic range is 41 dB one way.
43 citations
TL;DR: In this article, a planar monolithically integrated GaAs photoreceiver involving a transimpedance preamplifier has been fabricated using a metal-semiconductor-metal (MSM) photodiode.
Abstract: A planar monolithically integrated GaAs photoreceiver involving a transimpedance preamplifier has been fabricated using a metal‐semiconductor‐metal (MSM) photodiode. The present MSM photodiode showed a small capacitance of 0.14 pF, which is much smaller than in conventional p‐i‐n photodiodes, and a high‐speed pulse response exhibiting a rise time of 300 ps was demonstrated. It is shown that an MSM photodiode is suitable for monolithic integration due not only to the simple process but also because of its high‐speed operation.
29 citations
TL;DR: In this paper, a fully monolithic photoreceiver circuit incorporating an AlGaAs/GaAs p i n photodiode and a GaAs field effect transistor based transimpedance amplifier has been fabricated in the form of a horizontally integrated structure on a semi-insulating GaAs substrate.
Abstract: A fully monolithic photoreceiver circuit incorporating an AlGaAs/GaAs p‐i‐n photodiode and a GaAs field‐effect transistor based transimpedance amplifier has been fabricated in the form of a horizontally integrated structure on a semi‐insulating GaAs substrate. Parasitic capacitances of the circuit elements have been minimized in the present monolithic circuit, and a short rise and fall time of 1.0 ns, corresponding to an approximate −3 dB frequency of 300 MHz, has been demonstrated at the internal feedback resistance of 1.3 kΩ. Preliminary measurement of the noise characteristics of the present circuit has exhibited an encouraging value of the equivalent input noise current of 13 pA Hz−1/2 at 300 MHz.
27 citations
Patent•
06 Jun 1985TL;DR: A transimpedance amplifier for data signals from a high impedance source includes a forward voltage amplifier and a feedback resistance as discussed by the authors, which is controlled by a differentiator which generates pulses for each data transition and an average detector which generates a control signal responsive to the number of transitions per unit time, which is the data rate.
Abstract: A transimpedance amplifier for data signals from a high impedance source includes a forward voltage amplifier and a feedback resistance. The feedback includes an FET. The resistance of the FET is controlled by a control signal derived from the data signal at the output of the transimpedance amplifier by a differentiator which generates pulses for each data transition and an average detector which generates a control signal responsive to the number of transitions per unit time, which is the data rate. The resistance of the FET is high when the data rate is low, reducing the noise magnitude and decreasing the noise bandwidth. When the data rate increases, the resistance of the FET decreases, providing greater bandwidth for handling the signal. The change in gain caused by the bandwidth control tends to change the magnitude of the output data signal. This may be corrected by an AGC loop which controls the open loop gain of the voltage amplifier. In order to reduce the effect of differences in the bit transition time, a limiter may be coupled to the bandwidth control signal generator.
23 citations
Patent•
09 Sep 1985
TL;DR: In this article, the drain voltage of a field effect transistor (FET) in a transimpedance amplifier is connected by a capacitor (211) to the emitter (256) of a PNP transistor.
Abstract: The drain (250) of a field effect transistor (202) in a transimpedance amplifier is connected by a capacitor (211) to the emitter (256) of a PNP transistor, (203) thereby permitting the drain voltage of the field effect transistor to vary about a predetermined value without adjusting the drain resistance. When such a transimpedance amplifier is used in an optical receiver, the power requirements, current drain and supply voltage requirements are all reduced.
14 citations
Patent•
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TL;DR: In this article, a video coupler device capable of providing high effective electrical isolation between an analog video signal source system and a signal receiving system is disclosed. The device includes a high speed LED and a high-speed, linear, integrated circuit.
Abstract: A video coupler device capable of providing high effective electrical isolation between an analog video signal source system and a signal receiving system is disclosed. The device includes a high-speed LED and a high-speed, linear, integrated circuit. The integrated circuit includes a photodiode, an input current amplifier and an output transimpedance amplifier. The resultant video coupler exhibits a high degree of linearity and stability at a low cost, while requiring minimal external circuitry to handle standard video signals.
13 citations
TL;DR: In this paper, a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission was proposed, which achieved an optical sensitivity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10-10.
Abstract: This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlingtou circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitivity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.
11 citations
Patent•
11 Dec 1985
TL;DR: In this paper, an additional circuit is provided which contains a non-linear two-terminal network, e.g., a diode with low capacitance, which increasingly feeds the direct current of the photodiode through the twoterminal networks as the direct currents level rises, thus reducing the latter's differential resistance, so that the AC output voltage of the optical receiver increases only to an insignificant extent when the optical receive signal levels are high and as the AC photocurrent rises.
Abstract: In optical receivers which essentially comprise a photodiode (1) and a transimpedance amplifier (2, 3), it must be ensured in many applications that the transimpedance amplifier is not overloaded when the optical receive signal levels are high. According to the invention, an additional circuit is provided which contains a non-linear two-terminal network, e.g. a diode (7), with low capacitance and which increasingly feeds the direct current of the photodiode through the two-terminal network as the direct current level rises, thus reducing the latter's differential resistance, so that the AC output voltage of the optical receiver increases only to an insignificant extent when the optical receive signal levels are high and as the AC photocurrent rises.
8 citations
TL;DR: In this article, the factors limiting speed, sensitivity and dynamic range in p-i-n-b. transimpedance pre-amplifiers for optical receivers are examined.
Abstract: The factors limiting speed, sensitivity and dynamic range in p-i-n-b.j.t. transimpedance pre-amplifiers for optical receivers are examined. It is shown that a common-collector front end design is the best input configuration if a wideband response with good sensitivity is required. Two low-cost discrete pre-amplifier designs suitable for 140 Mbit/s and 650 Mbit/s are presented, together with three monolithic integrated circuits. The i.c.s were used in 320 Mbit/s receivers and had typical sensitivities of Â?34.6 dBm and optical dynamic ranges of at least 18.4 dB. The effect of circuit parasitics and of reducing transistor geometry on the i.e. performance is examined.
7 citations
TL;DR: In this paper, a monolithic transimpedance preamplifier with a common collector cascode configuration with shunt feedback, using an advanced bipolar IC process, was developed.
Abstract: A monolithic transimpedance preamplifier has been developed having a common-collector cascode configuration with shunt feedback, using an advanced bipolar IC process. The measured sensitivity was -35.0 dBm at 140 Mbit/s for an error rate of 10-9and a p-in photodiode responsivity of 0.5 A/W.
7 citations
01 Jan 1985
TL;DR: In a system to be described a linear array of 27 photodiodes is used to convert optical signals into current pulses that are subsequently converted to voltages with an array of27 transimpedance amplifiers.
Abstract: In a system to be described a linear array of 27 photodiodes is used to convert optical signals into current pulses that are subsequently converted to voltages with an array of 27 transimpedance amplifiers. The 27 channel system includes photodiodes integrated using an N well CMOS process with 2μ minimum feature sizes.
TL;DR: In this paper, a low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitiyity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10-10.
Abstract: This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlington circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitiyity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.
Patent•
22 Feb 1985TL;DR: In this article, a digital gain controlled current to voltage amplifier with a photomultiplier tube being responsive to light for producing an analog current proportional to the intensity thereof is described.
Abstract: A digital gain controlled current to voltage amplifier having particular utility for interfacing with and forming part of a spectrophotometer system with a photomultiplier tube being responsive to light for producing an analog current proportional to the intensity thereof. The digital gain controlled current to voltage amplifier incorporates a current switched multiplying digital-to-analog converter inside its feedback loop. In this manner, the feedback loop impedance may be maintained constant as its gain is varied under control of a software programmed microcomputer.
Journal Article•
TL;DR: In this article, the methode avec collecteur commun est la meilleure configuration, si on demande une reponse large bande avec bonne sensibilite.
Abstract: Etude des facteurs limitant la vitesse, la sensibilite la gamme dynamique dans les preamplifications a transimpedance p-i-n pour les recepteurs optiques. On montre que la methode avec collecteur commun est la meilleure configuration, si on demande une reponse large bande avec bonne sensibilite
TL;DR: In this article, a paralleling input stage was developed to meet the requirements for a low-noise, wideband preamplifier that matched the transmissionline impedance of ultrahigh-sensitivity fission counters.
Abstract: A new concept of paralleling input stages was developed to meet the requirements for a low-noise, wideband preamplifier that matches the transmissionline impedance of ultrahigh-sensitivity fission counters. The prototypic preamplifier consists of four dual-feedback-path amplifiers and a summing amplifier. It has an 18-pA/?Hz equivalent input noise current density, a 60-MHz bandwidth, a 25-? input impedance, and a 5-k? transimpedance.
Patent•
30 Oct 1985
TL;DR: In this article, the front end of an optical receiver circuit with a field effect device transimpedance amplifier and a direct current feedback resistor is shown to prevent the d.c. component of large photocurrents from significantly changing the input bias voltage level of the amblitier.
Abstract: 57 The front end of an optical receiver circuit (10) is of the type having a field-effect device transimpedance amplifier (16, 21) which receives at its input (14) the photocurrent of a photodiode (12). A field-effect device shunt impedance (26) to protect against amplifier overloading is connected between the input and ground through a decoupling capacitor (28). The shunt (26) is controlled by a controller (30), which has its input connected to the output (24) of the amplifier (16) and its output connected to the gate of the shunt (26). The controller (30) compares the output (24) of the amplifier (16) to a threshold reference voltage for determining whether to activate the shunt (26) and regulates the gate voltage of the shunt (26) by means of an AGC amplifier. A direct current feedback resistor (32) is connected between the output (24) of the amplifier (16) and the source of the shunt (26). This prevents the d.c. component of large photocurrents from significantly changing the input bias voltage level of the amblitier (16).
11 Feb 1985
TL;DR: The design details and experimental results of a circuit configuration having a performance that is insensitive to transconductance variations and is less sensitive to detector capacitance than previous implementations are presented.
Abstract: Implementations of the popular PIN/FET transimpedance amplifier1 exhibit performance directly dependent on transconductance of the field effect transistor and the input capacitance due to the detector. These dependencies cause the amplifier bandwidth to vary from device to device and with time or temperature. This paper presents design details and experimental results of a circuit configuration having a performance that is insensitive to transconductance variations and is less sensitive to detector capacitance than previous implementations.
TL;DR: In this article, the experimental and analytical studies of the light amplification of the Fabry-Perot type lasers were reported. And the authors showed that the waveform distortion is caused by the peaks of the spectrum shift of the input and the amplifier, which is not the same as the actual bias current.
Abstract: This paper reports the experimental and analytical studies of the light amplification of the Fabry–Perot type lasers. Particularly, for high bias current level of the laser amplifier, say more than 90% of the threshold current, the waveform distortion of the amplified output becomes apparent. Considering the following facts that the time division spectra of the input pulse to the amplifier changes from shorter to longer wavelengths due to temperature increase in the active layer after the pulse current is turned on and the peaks of the amplification factors of the Fabry–Perot type amplifiers depend on the wavelength for the different bias current level, we can show that the waveform distortion is caused by the peaks of the spectrum shift of the input and the amplifier. We also observe an important fact that the effective bias current to the amplifier is not the same as the actual bias current, which causes the wavelength shift of the peak gain of the amplifier, because of the reduction of the carrier concentrations in the active layer due to stimulated emission by the input light pulse. Taking into account these facts, the analytical and experimental results are in good agreement with each other.
Patent•
10 Jul 1985TL;DR: In this paper, an AGC shunt device is connected between its input nodes and the shaping section of a photodiode and a transimpedance amplifier to maintain the frequency response of the shaping area.
Abstract: The circuit (34) is of the type having an input section (12) and a shaping section (22). The input section includes a photodiode (14) and a transimpedance amplifier (16) with an AGC shunt device (19) connected between its input nodes (+,-). The shaping section includes, in order, an AGC amplifier (24), an equalizer amplifier (26), a buffer amplifier (42), and a filter (44). A controller (36) responsive to the photocurrent controls the impedance value of a dynamic impedance in the equalizer so that the frequency zero of the equalizer tracks the pole frequency of the input section as it changes in the course of changes in the value of its AGC shunt. This maintains the frequency response of the shaping section so that it continues to compensate for the frequency response characteristic of the input section. A trigger (52) responsive to the impedance value of the shunt activates the equalizer only when the shunt is active. Also disclosed is a particularly advantageous differential configuration for the equalizer which includes a diode bridge (76, 78, 80, 82) and four setting resistors (R1, R2, R1', R2') by which the break points for the frequency response can be set.
TL;DR: Results demonstrate that the popular p-i-n FET transimpedance amplifier is adversely sensitive to FET transconductance variations and distorts the pulse reponse, whereas the distributed gain and dual feedback design is substantially independent of transistor parameters and free of pulse distortion.
Abstract: Two conceptually different p-i-n FET receiver circuit architectures are evaluated using a SPICE circuit simulation. The popular p-i-n FET transimpedance amplifier is compared to a new architecture that uses distributed gain and dual feedback. To highlight the importance of circuit architecture to receiver performance, identical device parameters are used in each circuit model. Frequency, phase, and pulse responses are computed and presented in graphical form. Results demonstrate that the popular receiver is adversely sensitive to FET transconductance variations and distorts the pulse reponse, whereas the distributed gain and dual feedback design is substantially independent of transistor parameters and free of pulse distortion.
TL;DR: Results demonstrate that the popular p-i-n FET transimpedance amplifier is adversely sensitive to FET transconductance variations and distorts the pulse reponse, whereas the distributed gain and dual feedback design is substantially independent of transistor parameters and free of pulse distortion.
Abstract: Two conceptually different p-i-n FET receiver circuit architectures are evaluated using a SPICE circuit simulation. The popular p-i-n FET transimpedance amplifier is compared to a new architecture that uses distributed gain and dual feedback. To highlight the importance of circuit architecture to receiver performance, identical device parameters are used in each circuit model. Frequency, phase, and pulse responses are computed and presented in graphical form. Results demonstrate that the popular receiver is adversely sensitive to FET transconductance variations and distorts the pulse reponse, whereas the distributed gain and dual feedback design is substantially independent of transistor parameters and free of pulse distortion.
22 Aug 1985
TL;DR: A computer program was developed to aid the design of fibre optic receiver preamplifiers for low/medium bit rate systems and can be used to understand the effects of various system parameters on the receiver sensitivity without having to actually construct the circuits.
Abstract: A computer program was developed to aid the design of fibre optic receiver preamplifiers for low/medium bit rate systems. The program calculates the preamplifier feedback resistance and, in the case of avalanche photodiode, the optimum multiplication factor. The program can work with any of the three basic receiver types viz: straightforward termination, high impedance integrating type and the transimpedance type. It can be used to understand the effects of various system parameters on the receiver sensitivity without having to actually construct the circuits.
Patent•
07 Jan 1985
TL;DR: In this article, a voltage-to-current transducer is converted to a unit having a variable current output in response to the normal output voltage with the minimum current drawn by the unit being only slightly greater than that required to operate the basic voltage-type transducers.
Abstract: A pressure or other transducer (12) having a normal variable voltage output is converted to a unit having a variable current output in response to the normal output voltage with the minimum current drawn by the unit being only slightly greater than that required to operate the basic voltage-type transducer. The new current output system includes a voltage regulator (14) and a voltage-to-current converter (16). The voltage-to-current converter (16) includes an operational amplifier (28) and an output transistor (30), with one input to the operational amplifier (28) being set at a voltage equal to the output voltage of the voltage-type pressure transducer (12) at zero pressure. The output from the voltage-type pressure transducer (12) is connected through a first gain adjusting potentiometer (R7) to the second input (34) of the operational amplifier (28); and an additional offset adjustment potentiometer (R3) is connected between the output of the voltage regulator (14) and the junction between the gain adjustment potentiometer (R7) and the second input (34) to the operational amplifier (28). The voltage regulator (14) and the voltage-to-current converter (16) may both include output buffering transistors. Where the voltage-type pressure transducer (12) draws about 3.5 milliamperes, the minimum current from the entire system is only about 4 milliamperes, and may even be set below 4 milliamperes.