Showing papers on "Transimpedance amplifier published in 1987"

Hall effect device with epitaxal layer resistive means for providing temperature independent sensitivity

Abstract: A linear Hall effect integrated circuit in which the output signal of a Hall element formed in an epitaxial layer is amplified by an amplifier circuit whose gain is determined by a resistor partially formed in the same epitaxial layer. A first amplifier stage configured as a voltage to current converter is connected through a current mirror to a second amplifier stage configured as a current to voltage converter. The current bias for the first amplifier stage is controlled by a resistor also partially formed in the epitaxial layer.

Fast CMOS current amplifier and buffer stage

Abstract: A novel CMOS current amplifier stage is described which provides a low impedance and an accurately controlled DC bias voltage at its input terminal, as well as an accurate current gain in a wide frequency range.

Transimpedance optical preamplifier with a very low input resistance

Abstract: A PIN photodiode-bipolar transistor transimpedance optical preamplifier with a very low input resistance is described that exhibits certain advantages over more conventional designs using common-emitter or common-collector input stages The common-base input configuration enables optimum performance to be maintained with lower-cost photodiodes exhibiting a moderate capacitance of 2-7 pF

On the noise optimum of gigahertz FET transimpedance amplifiers

Abstract: The main figure of merit for transimpedance amplifiers used in amplifying photocurrents in fiber-optic systems is the optical sensitivity. This sensitivity is determined by the equivalent input noise current of the amplifier. To obtain the best noise performance, most transimpedance amplifiers with FET input stages are designed using a result that prescribes making the capacitance of the input FET equal to the photodiode capacitance. It is shown here that this is not necessarily the most favorable practice when using FETs in scaled submicrometer technologies because it may compromise the stability of the amplifier. The tradeoff in sensitivity to obtain better stability is examined.

GaAs monolithic integrated optical preamplifier

Abstract: A GaAs monolithic integrated optical preamplifier has been developed based on the transimpedance principle. By associating the amplifier with an external p-i-n diode, a sensitivity of -38 dBm was measured at 140 Mbits/s and 10-9error rate with a signal wavelength of 1.3 μm. A TiWSiN-integrated technology was used to realize larger than 100-kω feedback resistors and gate leakage could be minimized by improving Schottky contact deposition and employing selective implantation. The optimization details of the FET and resistor elements, as well as the design techniques for integrated transimpedance amplifiers are presented.

Low noise, high speed current or voltage amplifier

Abstract: A low noise, high speed current transimpedance amplifier system (20) includes AC bootstrapping for the photodiode D1 by capacitor C2 connected between the source of the JFET Q1 and the cathode of the photodiode D1 by line (56). Line (58) also provides AC bootstrapping to the case of the module (40) through capacitor C2. Similarly, the source resistor R3 and drain of JFET Q1 are AC bootstrapped through capacitors C1 and C4 to the emitters of the transistors Q2 and Q4 by lines (60) and (62). The collectors of the second stage transistors Q2 and Q4 are bootstrapped to the third stage transistor Q3 emitter through capacitor C8 by line (64). This bootstrapping reduces the effective input capacitance at the front end of the amplifier system (20) by a factor of up to about 100, thus reducing signal noise component in the subsequent stage or stages to negligible compared to front end noise.

Microwave temperature compensated cascadable amplifier for fiber optical receiver

Abstract: A temperature compensated amplifier network for a fiber optical receiver includes a photodiode having an optical input and a current output, and a cascadable transimpedance amplifier having N stages, each stage having a common base-emitter voltage. An emitter-follower transistor is coupled to the last stage of the transimpedance amplifier network and has a base-emitter voltage of the same magnitude but of opposite polarity from the base-emitter voltage of each of the amplifier stages. Any DC drift of the amplifier stages is therefore offset by a compensating drift in the opposite direction by the output emitter-follower.

Receiver for optical digital signals with dark current compensation

Abstract: A receiver for optical digital signals has a transimpedance amplifier, the input of which is connected to an operating voltage via an active photodiode, and the output of which is connected to an input of a comparator. An operational amplifier is provided, the one input of which is connected to the input of the transimpedance amplifier, and the other input of which is connected to the operating voltage via a further, unilluminated photodiode. A reference voltage at the other input of the comparator is generated from the output voltage of the operational amplifier via a voltage divider.

Receiver for optical digital signals having different amplitudes

Abstract: A receiver for optical digital signals which have different amplitudes which comprises a transimpedance amplifier which has a photodiode connected to its input and which produces an output that is supplied to one of the inputs of a comparator. Oppositely poled diodes are connected between the inputs of the comparator and a reference voltage is supplied to the other input of the comparator and a capacitor is connected to the other input of the comparator which together with a resistor comprises a differentiator for the output signals of the transimpedance amplifier.

Fiber optic receiver

Abstract: An optical receiver especially useful for digital fiber optic systems operating a high pulse rates, converts the pulsed current signal generated by a PIN diode into a pulsed voltage utilizing a current to voltage converter comprising an FET input transistor, a complimentary cascoded bipolar transistor, and a large feedback resistor to reduce noise while providing a wide band width and dynamic range. The pulsed voltage signal is amplitude limited in a limiting amplifier and passed through a low pass filter to remove excess bandwidth and further reduced noise before being applied to a high speed comparator which generates the digital output. The pulsed voltage signal is passed from the current to voltage converter to the limiting amplifier through an emitter follower coupling transistor to isolate the open loop gain of the current to voltage converter so that its band width will not be changed with load.

Dynamically biased voltage controlled element

Abstract: A method and apparatus for regulating a voltage controlled amplifier to operate within Class A and Class AB extremes generate a bias control signal from one or more signals in a system including the voltage controlled amplifier and applying the bias control signal to the voltage controlled amplifier to affect operation within the extremes.

On the noise of high-transimpedance amplifiers for long-wavelength pulse OTDRs

Abstract: Noise measurements on high-transimpedance amplifiers suitable for long-wavelength OTDRs give results higher than is predicted by normal noise models. Consequently, we have developed two useful techniques to measure independently the noise contribution of the JFET and the feedback resistor to the overall amplifier noise. p ]Our results show that the noise of the JFET is in accordance with an accurate theoretical model for such a device. In contrast, the noise from the feedback resistor is much higher than is predicted from the normal resistance-capacitance model for such a component. This increase results from the distributed nature of high-ohmic resistors. Our results indicate that both choice of resistor manufacturer and individual selection of a resistor from a specific manufacturer are warranted. By selecting a low-noise resistor we demonstrate a 500-MΩ transimpedance amplifier with an input equivalent noise current of 13.8 pA. In comparison, the same amplifier with a noisy resistor had an input equivalent noise current of 23 pA. p ]We use our results to show that a reasonable value of the input equivalent noise current of a low-noise photodiode-amplifier combination is 20 pA.

Current mirror with unity gain buffer

Abstract: An improved current mirror is described which has utility as either a stand alone current source or as a gain block whenever current gain or transimpedance gain is required. When used as a current source the current mirror exhibits higher output impedance, and when used as a gain block, the current mirror exhibits improved higher frequency performance and high transimpedance gain than prior art current mirrors.

5.2GHz monolithic GaAs optoelectronic receiver

Abstract: A 5.2GHz monolithic GaAs optoelectronic receiver will be presented. It consists of an interdigitated Schottky-barrier photodiode integrated with a GaAs transimpedance amplifier. The amplifier has an enhancement driver/depletion load input stage connected to a source follower matched to 50Ω. The circuit is implemented with 0.35µm recessed-gate GaAs MESFET's. The receiver is fully DC coupled and is compatible with E/D MESFET logic circuits. We obtained a bandwidth of 5.2GHz for an effective transimpedance into a 50Ω load of 300Ω yielding a transimpedance-bandwidth product of 1.5THzΩ. We also report on a single photodiode fabricated within a 100Ω transmission line, which was measured using 1.8ps laser pulses and yielded an electrical pulse with FWHM of only 4.8ps. This corresponds to a bandwidth of 105GHz.

A CMOS 120 mW 8-bit Voltage Output Video DAC using a Current-Cell Matrix

Abstract: This paper describes an 8-bit CMOS video speed D/A converter fabricated in a 2.4 ?m CMOS technology. In order to achieve monotonicity and static linearity, a current cell-matrix configuration has been used. The linearity errors due to the voltage drop along the reference lines has been reduced by the choice of a small full-scale current (2 mA). A very simple cell structure has been adopted to reduce the matrix area. In order to perform a high speed operation, a high speed decoding circuit with one stage latches has been developed. The design of a transimpedance amplifier at the output of the matrix allows a fast settling time with a low impedance output. The experimental results show that the maximum convertion rate is 33 Mhz, the dc integral and differential linearity errors are 0.25 LSB and the typical power consumption is 120 mW. Recent developments in digital TV, and high picture quality requirements will lead to a more general use of an efficient and low cost video digital to analog converter. New video decoder architectures [1] and the introduction of the MAC standard [2] for direct satellite broadcasting have created a need for triple 8-bit D/A converters in the range of 27 Mhz for the sampling rate. Efficient architectures using CMOS technology have been proposed [3,4] which guarantee monotonicity and small area requirements.

Receiver for optical digital signals having various amplitudes

Abstract: Die Erfindung bezieht sich auf einen Empfanger fur optische Digitalsignale mit unterschiedlicher Amplitude, mit einem Transimpedanz-Verstarker (TIV 1), an dessen Eingang eine Fotodiode (FD) angeschaltet ist, und dessen Ausgang an einen Eingang eines Komparators (K) angeschaltet ist. The invention relates to a receiver for optical digital signals with different amplitude, with a transimpedance amplifier (TIV 1), at whose input a photodiode (FD) is turned on, and its output to an input of a comparator (K) is turned on. Erfindungsgemas sind zwischen die Eingange des Komparators antiparallele Dioden (D1, D2) geschaltet, liegt eine Referenzspannung (VR) am anderen Eingang des Komparators an, und ist eine Kapazitat (C1) ebenfalls am anderen Eingang des Komparators angeschaltet, die zusammen mit einem Widerstand (R2) fur die Ausgangssignale des Transimpedanz-Verstarkers ein Differenzierglied darstellt. According to the invention between the inputs of the comparator anti-parallel diodes (D1, D2) connected, is situated on a reference voltage (VR) at the other input of the comparator, and a capacitor (C1) is also connected at the other input of the comparator, which (together with a resistor R2) is a differentiating element for the output signals of the transimpedance amplifier.

Electronic variable resistor circuit

Abstract: PURPOSE: To easily set control over the amplification gain of an amplifier to A type variable resistor characteristics artificially by providing plural output transistors(TR) according to the result of comparison between a reference voltage set by a reference voltage circuit and a control voltage. CONSTITUTION: When the control voltage VC is increased linearly from 0V by operating a variable resistance 20, a current IA is obtained from an output TR 32 by a voltage-current converting circuit 30 and when the control voltage VC reaches the reference voltage VB 1 , a current IB is obtained from an output TR 33, but when the control voltage VC reaches a reference voltage VB 2 , a current IC is obtained from an output TR 34. Those currents IA∼IC are put together through a current composing circuit 50 to obtain a composite current IT approximating to A type variable resistor characteristics. This composite current IT becomes the operating current of the amplifier 60 and the amplification gain of the amplifier 60 becomes A type variable resistor characteristics as increase characteristics of the composite current IT; and an input signal V i is increased or decreased in level by the variable resistor characteristics to become an output signal V o . COPYRIGHT: (C)1988,JPO&Japio

Miniaturized DC-300 Mb/s Optical Transmitter/Receiver Modules For Burst Signal Transmission

Abstract: A miniturized D( to 300Mb/s optical transmitter and receiver modules have been developed. The optical transmitter utilizes an InGaAsP/InP surface emitting LED (the center wavelength is 1315nm) as a light source. The pulse width distortion is maintained less than ± 0.2nsec because the compensation circuit is employed to adjust the LED's response. The optical receiver utilizes an InGaAs/InP PIN-photodiode which responsivity is 0.82A/W for 62.5/125 GI 0.29NA fibers. Pre-amplifier using a Si-IC, has a transimpedance of 10kΩ and bandwidth of 200MHz. Automatic Threshold Control (ATC) circuit utilizes high speed peak-hold circuit technique to respond to burst signal within several handred nano-seconds. And in order to prevent the appearance of error pulses at extinct input, Automatic Threshold Bias-level Control (ATBC) circuit is employed. By the use of ATC and ATBC circuit, the receiver can receive the burst optical signal, which include a continuous extinct level, in short settling time and slight pulse width distortion.

Gaas Monolithic Receiver And Laser Driver For Ghz Transmission Rates

Abstract: As the availability of commercial GaAs integrated circuits increases, gigabit optical fiber transmission systems will soon be a reality. Since commercially available lasers and PIN diodes already operate well over a gigabit, the only limiting factor to commercially feasible high data rate systems are the high speed circuits required in the transmitters and receivers. The circuits that require ultra high speed are shown in Figure 1. Microwave Semiconductor Corp. has recently announced a fiber optic chip set that will perform each function shown in Figure 1, excluding the laser and PIN diode. This paper will describe two of the new GaAs integrated circuits, the laser driver and the transimpedance receiver circuit, that operate above a gigahertz.

A 500V/µs 12b transimpedance amplifier

Abstract: A current-to-voltage amplifier with ±10 V output capability, and a settling time of 120ns to 12b accuracy will be discussed. A 100MΩ transresistance, 20μV input offset voltage and 100nA input current were obtained in a junction isolated bipolar technology.

Frequency selective amplifier with gain control

Abstract: 1 Frequency selective, controlled, electronic amplifier circuit consisting of one of several stages and having an output for each stage which is provided by the output of a band filter (1) connected to the collector circuit of a transistor (2), whereas the controlling means of each stage is connected to the impedance (3) of the emitter of the transistor (2), which impedance (3) of the emitter circuit contains a frequency dependent element which is connected in parallel to a resistor (32) controlled by voltage, characterized in that the frequency dependent element is a member, preferably a capacitor or an in series connected RC-member, that the circuit is provided with a reference transmitter (4) and a comparing branch, in which a signal transmitter (51) connected to the output of the band filter (1), a resistor (52) with valve effect and a condensator (53) are connected in series, wherein the one end of the comparing branch is connected to the output (4b) of the reference transmitter (4), whereas the shared end of the resistor (52) and the condenser (53) is connected to the controlling end (3d) of the voltage controlled resistor (32)

A 20-/spl mu/W precision operational amplifier

Abstract: A precision operational amplifier is described which draws 12 /spl mu/A of quiescent current and can operate from a 1.6-V supply while requiring no external components such as the usual biasing resistor. The amplifier has DC characteristics comparable to the industry standard OP-07 and AC characteristics as good as currently available micropower devices. The circuit has an input voltage range and an output swing which include the negative supply to facilitate its use in battery-powered and other single-supply applications.

Low-frequency amplifier

Abstract: The invention relates to a low-frequency amplifier with an integrated push-pull B final stage and a circuit for adjusting the quiescent current. The invention resides in the amplifier comprising two circuits for adjusting the quiescent current which are provided for different voltage ranges of the supply voltage. An electronic switchover device ensures automatic activation of that circuit for quiescent current adjustment which is suited for the respective voltage range.

A 1.55-μm 565-Mb/s monolithically Integrated optical repeater with wide optical dynamic range

Abstract: In long-haul transmission systems, received optical powers of Individual repeaters differ significantly depending on repeater spacing. Build-out networks (BONs) have frequently been used to adjust for these differences. The development of BON-free repeaters would be advantageous from the standpoint of simplifying the installation and maintenance of transmission lines. A variable transimpedance preamplifier proposed by the authors can expand optical dynamic range and is useful for realizing BON-free optical repeaters.1 We report a 1.55-μm 565-Mb/s monolithically integrated optical repeater with a wide optical dynamic attained by use of the proposed preamplifier.