Showing papers on "Transimpedance amplifier published in 2000"

Bandwidth extension in CMOS with optimized on-chip inductors

Abstract: We present a technique for enhancing the bandwidth of gigahertz broad-band circuitry by using optimized on-chip spiral inductors as shunt-peaking elements. The series resistance of the on-chip inductor is incorporated as part of the load resistance to permit a large inductance to be realized with minimum area and capacitance. Simple, accurate inductance expressions are used in a lumped circuit inductor model to allow the passive and active components in the circuit to be simultaneously optimized. A quick and efficient global optimization method, based on geometric programming, is discussed. The bandwidth extension technique is applied in the implementation of a 2.125-Gbaud preamplifier that employs a common-gate input stage followed by a cascoded common-source stage. On-chip shunt peaking is introduced at the dominant pole to improve the overall system performance, including a 40% increase in the transimpedance. This implementation achieves a 1.6-k/spl Omega/ transimpedance and a 0.6-/spl mu/A input-referred current noise, while operating with a photodiode capacitance of 0.6 pF. A fully differential topology ensures good substrate and supply noise immunity. The amplifier, implemented in a triple-metal, single-poly, 14-GHz f/sub Tmax/, 0.5-/spl mu/m CMOS process, dissipates 225 mW, of which 110 mW is consumed by the 50-/spl Omega/ output driver stage. The optimized on-chip inductors consume only 15% of the total area of 0.6 mm/sup 2/.

A 3 GHz, 32 dB CMOS limiting amplifier for SONET OC-48 receivers

Abstract: An optical receiver front-end for SONET OC-48 (2.5 Gb/s) is shown. The limiting amplifier (LA) receives a small-non-return to zero (NRZ) voltage signal (e.g., 8 mV/sub pp/) from the transimpedance amplifier (TIA) and amplifies it to a level (e.g. 250 mV/sub pp/) sufficient for the reliable operation of the clock and data recovery circuit. The noise contribution of the LA must be small compared to that of the TIA so that the overall bit error rate and sensitivity are not affected adversely. Currently, commercial 2.5 Gb/s SONET systems are composed of several discrete chips implemented in GaAs and more recently silicon bipolar technology. The future trend, however, is to integrate most of the front-end together with the digital framer on a single CMOS chip. Furthermore, the integration of multiple 2.5 Gb/s channels on a single CMOS chip is desirable for wavelength division multiplexing (WDM) application. CMOS amplifiers for optical receivers and related applications with bandwidths up to 2.1 GHz are recently reported. This CMOS limiting amplifier with improved bandwidth (3 GHz) and noise figure (16 dB) is suitable for 2.5 Gb/s SONET receivers. Power dissipation is 53 mW and the chip is fabricated in a standard 2.5 V, 0.25 /spl mu/m CMOS technology. This result is achieved with: (i) Inverse scaling to increase gain-bandwidth and reduce power dissipation while keeping noise and offset voltage low and (ii) active inductors to increase gain-bandwidth and improve gain stability. The active area of the amplifier is 0.03 mm/sup 2/, less than 10% that of a comparable design with spiral inductors.

Design of low-voltage bandgap reference using transimpedance amplifier

Abstract: The minimum supply voltage for implementing a typical bandgap reference is usually over 1.8 V. This minimum is mainly due to the limited input common-mode range of the opamp used in the bandgap reference. In this work, a low-voltage bandgap reference using a transimpedance amplifier that does not have this limitation is proposed and some of the design considerations for the proposed technique are briefly discussed. Based on this technique, a 1.2-V bandgap reference was implemented in a 1.2-/spl mu/m CMOS process (V/sub TN//spl ap/0.53 V and V/sub TP//spl ap/-0.91 V) with bipolar option. The variations of the output voltage over temperature (0/spl deg/C/spl les/T/spl les/100/spl deg/C) were measured to be less than /spl plusmn/1%.

InP-InGaAs single HBT technology for photoreceiver OEIC's at 40 Gb/s and beyond

Abstract: We describe an advanced InP-InGaAs-based technology for the monolithic integration of pin-photodiodes and SHBT-transistors. Both devices are processed using the same epitaxial grown layer structure. Employing this technology, we have designed and fabricated two photoreceivers achieving transimpedance gains of 170 /spl Omega//380 /spl Omega/ and optical/electrical bandwidths of 50 GHz/34 GHz. To the best of our knowledge, this is the highest bandwidth of any heterojunction bipolar transistor (HBT)-based photoreceiver optoelectronic integrated circuit (OEIC) published to date. We even predict a bandwidth of 60 GHz for the same circuit topology by a simple reduction of the photodiode diameter and an adjustment of the feedback resistor value.

A 622 Mb/s 4.5 pA//spl radic/Hz CMOS transimpedance amplifier [for optical receiver front-end]

Abstract: High-speed transimpedance amplifiers (TIAs) used at the front end of optical fiber receivers present design challenges in the form of trade-offs between input noise current, speed, transimpedance gain, power dissipation, and supply voltage. This transimpedance amplifier in 0.6 /spl mu/m CMOS exhibits 4.5 pA//spl radic/Hz average input noise current, 622 Mb/s data rate, and 8.7 k/spl Omega/ transimpedance gain while dissipating 30 mW from a 3 V supply.

Measurement of current in a vehicle using battery cable as a shunt

Abstract: Current flowing into and out of a battery (1) installed in a vehicle (V) with the required cable (3) between one of the battery terminals and a reference point (8) on the vehicle is determined by measuring the voltage across the cable (3) and computing (22) the current from the digital value of the measured current. The resistance value of the cable can be known in which case the current is computed using Ohms low and a differential current sensor (30) can be used to respond to the voltage measured across the cable to accommodate for different ranges of current. In an embodiment where the cable (3) resistance is unknown, a reference current source (125) produces a known voltage (128) that is used to set the input value to an amplifier (111) of fixed gain for the voltage measured across the cable by controlling the output of a potentiometer (106) so that the amplifier output voltage can be set to match the reference current generator output voltage, thereby establishing the voltage output of the amplifier as a measurement of the current flow in the cable.

A high-speed monolithic silicon photoreceiver fabricated on SOI

Abstract: We report a monolithically integrated optical receiver fabricated on an SOI substrate. The receiver consists of a lateral p-i-n photodiode and an NMOS transimpedance preamplifier. At V/sub DD/=5 V, the receiver dissipated 37 mW of power with a typical transimpedance gain of 49 dB./spl Omega/. At operating speeds of 622 Mb/s and 1.0 and 2.0 Gb/s, the receiver achieved a bit error ratio of 10/sup -9/ at received powers of -31.6, -25.7, and -17.7 dBm, respectively.

A packaged low-noise high-speed regulated cascode transimpedance amplifier using a 0.6µm N-well CMOS technology

Abstract: Regulated cascode (RGC) techniques are applied to achieve better isolation of the large input parasitic capacitance in a front-end preamplifier for optical receiver applications, since the RGC circuit behaves like a common-gate transistor with large transconductance comparable to GaAs MESFET. The input resistance of the RGC circuit becomes smaller by the amount of the voltage-gain of the local feedback stage than that of a conventional common-gate input stage. Hence the RGC circuit gives a virtual-ground input impedance and better isolates the input parasitics. With this very low input impedance characteristic, a RGC transimpedance amplifier is realized with a 0.6µm digital CMOS process. This amplifier is packaged in a MQFP package, mounted on a copper PC-board, and housed in an aluminum metal box. The measured results demonstrate 300MHz bandwidth, 57.7dB Ω transimpedance gain, 10 pA/√Hz average noise current spectral density with ±6V power supply.

High-gain transimpedance amplifier in InP-based HBT technology for the receiver in 40-Gb/s optical-fiber TDM links

Abstract: A monolithic integrated transimpedance amplifier for the receiver in a 40-Gb/s optical-fiber TDM system has been fabricated in an InP-based HBT technology. Despite its high gain (transimpedance of 2 k/spl Omega/ in the limiting mode, 10 k/spl Omega/ in the linear mode) the complete amplifier was realized on a single chip. Clear output eye diagrams were measured up to 43 Gb/s under realistic driving conditions. The voltage swing of 0.6 V/sub pp/ at the differential 50 /spl Omega/ output does not change within the demanded input dynamic range of 6 dB. At the upper input current level even 48 Gb/s were achieved. The power consumption is approximately 600 mW at a single supply voltage of -5.5 V.

Monolithically integrated multichannel SiGe/Si p-i-n-HBT photoreceiver arrays

Abstract: A low-power, short-wavelength eight-channel monolithically integrated photoreceiver array, based on SiGe/Si heterojunction bipolar transistors, is demonstrated. The photoreceiver consists of a photodiode, three-stage transimpedance amplifier, and passive elements for feedback, biasing and impedance matching. The photodiode and transistors are grown by molecular beam epitaxy in a single step. The p-i-n photodiode exhibits a responsivity of 0.3A/W and a bandwidth of 0.8 GHz at /spl lambda/=0.88 /spl mu/m. The three-stage transimpedance amplifier demonstrates a transimpedance gain of 43 dB/spl Omega/ and a -3 dB bandwidth of 5.5 GHz. A single channel monolithically integrated photoreceiver consumes a power of 6 mW and demonstrates an optical bandwidth of 0.8 GHz. Eight-channel photoreceiver arrays are designed for massively parallel applications where low power dissipation and low crosstalk are required. The array is on a 250-/spl mu/m pitch and can be easily scaled to much higher density. Large signal operation up to 1 Gb/s is achieved with crosstalk less than -26 dB. A scheme for time-to-space division multiplexing is proposed and demonstrated with the photoreceiver array.

49-GHz preamplifier with a transimpedance gain of 52 dB/spl Omega/ using InP HEMTs

Abstract: We developed a new preamplifier with a transimpedance gain of 52 dB/spl Omega/ and 49 GHz bandwidth using 0.15-/spl mu/m InP based high electron mobility transistors (HEMTs). The preamplifier consists of a lumped element designed transimpedance amplifier for an input stage and a distributed amplifier for a gain stage. A highly stabilized and ultra-broad band distributed amplifier with gain-peaking techniques was successfully designed. This technique provides a preamplifier ultra-broad bandwidth and excellent gain flatness.

45 GHz transimpedance 32 dB limiting amplifier and 40 Gb/s 1:4 high-sensitivity demultiplexer with decision circuit using SiGe HBTs for 40 Gb/s optical receiver

Abstract: A preamplifier with 45 GHz bandwidth and 50.2 dB/spl Omega/ transimpedance gain, a limiting amplifier with 32 dB gain and 49 GHz bandwidth, and a 40 Gb/s 1:4 high-sensitivity demultiplexer (HS-DEMUX) combined with a decision circuit are for use in a 40 Gb/s optical receiver. The bandwidth in the preamplifier and the maximum gain at 40 GHz in the limiting amplifier are the best reported for any semiconductor technology. The 1:4 HS-DEMUX uses bit-rotation for byte-synchronization.

A new floating controlled resistance operating in class AB

Abstract: A new implementation for a floating controlled resistance operating in class AB is introduced. This uses a new translinear mixed loop of eight bipolar transistors. The circuit has been biased with DC current in such a way that it works effectively in class AB. A new building block, the third-generation controlled current conveyor (CCCIII) is then implemented. This has been obtained simply by adding a supplementary output terminal Z to duplicate the current flowing through the controlled resistance above. Simulation results, using the nominal parameters of the ALA200 bipolar arrays from ATT, demonstrate the high possibilities of the circuit. With /spl plusmn/1.5 V supply voltage, the power consumption of this wideband conveyor (-3 dB bandwidths greater than 30 MHz) is less than 7 mW as soon as the controlled resistance becomes lower than 250 /spl Omega/. An application example, consisting of a sinusoidal controlled oscillator, implemented from a transimpedance operational amplifier, is finally given to illustrate the versatility of the circuit.

Optical receiver with a control loop providing wide dynamic range

Abstract: The invention relates to an optical receiver comprising a transimpedance amplifier ( 21 ) and a photo detector (PD) for converting the optical power arriving at the receiver into electric current. To enable a good dynamic range to be achieved for the receiver in a simple way, the transimpedance amplifier is a differential amplifier provided with two inputs. Furthermore, the receiver comprises separating means (LPU) for separating a direct voltage component from the output voltage of the transimpedance amplifier and means (VCU) for supplying a direct voltage dependent on the direct current component to that input of the transimpedance amplifier which is different from the input used by the photo detector.

A 1 GHz CMOS transimpedance amplifier for chip-to-chip optical interconnects

Abstract: A CMOS transimpedance amplifier (TIA) has been designed and tested for cost effective chip-to-chip optical interconnects. The amplifier is based on a foundry standard CMOS technology which features 0.8 /spl mu/m drawn channel length, double-poly capacitors and poly-Si resistors. Measurements showed a transimpedance gain of 48 dB/spl Omega/ over a -3 dB bandwidth of DC-1 GHz and a power consumption of 80 mW when biased at +5 V and AC coupled to the load. The biasing circuitry consumes an additional 52 mW. The mean input referred noise current density was calculated to be 7.4pA//spl radic/Hz, which results in an input optical sensitivity of -25.7 dBm for a BER of 10/sup -9/. The experimental results verify to a great extent the expected transmission rate of up to 1.8 Gbps.

Low FPN high gain capacitive transimpedance amplifier for use with capacitive sensors

Abstract: An amplifier for measuring the charge stored on a source capacitor having a capacitance C pd . The amplifier includes an opamp having a signal input, reference input and output; the first terminal of the source capacitor is connected to the signal input. The amplifier includes a reset switch for shorting the signal input and the output of the opamp, and a capacitive network. The capacitive network connects the signal input and the output of the opamp, and provides a capacitance of C T between the signal input and the output of the opamp wherein C T

Current monitoring circuit for secondary battery

Abstract: A current monitoring circuit for monitoring a charging/discharging current of a secondary battery that achieves high-precision monitoring and that restricts an increase in the circuit scale. An amplifier amplifies a voltage of a current sense resistor generated by a charging/discharging current under a various amplification degrees. A comparator compares an output voltage of the amplifier with a reference voltage. A controller controls a reference voltage to be supplied to each unit and controls the amplification degree of the amplifier, based on a result of the comparison. An A/D converter A/D converts an output voltage of the amplifier. A numerical-value converter converts a digital value obtained by the conversion of the A/D converter into a numerical value corresponding to a charging/discharging current, under the control of the controller. When an excess current has been detected, a switch is set to a non-conductive state, to thereby disconnect the battery from the external unit.

Optical receiving circuit and optical communication device

Abstract: An optical receiving circuit 1 is composed of a preamplifier circuit 2, an output differential amplifier 3 and a mean value holding circuit 4. The optical receiving circuit 1 is connected to a photodetector 5 for receiving an input optical signal and outputting current. For the preamplifier circuit 2, a transimpedance type circuit may also be used. The preamplifier circuit 2 comprises a feedback resistor 21 and a resistor for detecting output voltage 22, the transimpedance gain is 55 dB Ω and 3 dB bandwidth when the photodetector 5 the capacity of which is 0.2 pF is connected to its output is 8 GHz. The output differential amplifier 3 discriminates and regenerates data by regulating reference voltage Vref between the high level and the low level of the amplitude of an input signal. The mean value holding circuit 4 includes a sample-hold circuit 41 and capacity 42 for holding the mean value of voltage output from the preamplifier circuit 2. As a CR time constant based upon the capacity 42 and the resistor for detection 22 is 1 ns., the mean value level of a received signal can be detected in approximately one byte of the data of 10 Gb/s. The sample-hold circuit 41 samples the detected mean value level according to a sampling pulse from an external device and holds it. The output of the sample-hold circuit 41 is used for the reference voltage of the differential amplifier 3.

3-V MSM-TIA for Gigabit Ethernet

Abstract: The paper describes a 3-V monolithically integrated metal-semiconductor-metal photodetector (MSM-PD) and transimpedance amplifier (TIA) chip that is fully compliant with the Gigabit Ethernet receiver specification for the short-reach application (IEEE 802.3z 1000BASE-SX). Key typical performance specifications are -22 dBm sensitivity, 1200 MHz 3-dB bandwidth, 1300-V/W differential responsivity, and 120-mW power dissipation at 3 V. The chip is fabricated in a production 0.5-/spl mu/m gate length GaAs MESFET technology and is packaged in a TO-46 header with a flat window and a ball-lens cap option.

High gain detector amplifier with enhanced dynamic range for single photon read-out of photodetectors

Abstract: An ultra-low noise, high gain interface pixel amplifier is provided with capability for single-photon readout of standard photodetectors at high electrical bandwidths for diverse spectral bandpass from the x-ray to long IR bands. The detector charge modulates a source follower whose output is double sampled to remove correlated noise by a compact stage that also provides optimum level shift for subsequent amplification of the full signal excursion. The level-shifted signal finally drives a compact amplifier that generates a robust end-to-end transimpedance. Single-photon readout of photodetectors at high electrical bandwidths in small pixel areas is thereby facilitated.

Noise Optimized Silicon Radiometers

Abstract: This paper describes a new, experimentally verified, noise analysis and the design considerations of the dynamic characteristics of silicon radiometers. Transimpedance gain, loop gain, and voltage gain were optimized versus frequency for photodiode current meters measuring ac and dc optical radiation. Silicon radiometers with improved dynamic characteristics were built and tested. The frequency-dependent photocurrent gains were measured. The noise floor was optimized in an ac measurement mode using photodiodes of different shunt resistance and operational amplifiers with low 1/f voltage and current noise. In the dark (without any signal), the noise floor of the optimized silicon radiometers was dominated by the Johnson noise of the source resistance. The Johnson noise was decreased and equalized to the amplified 1/f input noise at a 9 Hz chopping frequency and 30 s integration time constant, resulting in an equivalent root-mean-square (rms) photocurrent noise of 8 × 10(-17) A. The lowest noise floor of 5 × 10(-17) A, equal to a noise equivalent power (NEP) of 1.4 × 10(-16) W at the 730 nm peak responsivity, was obtained at a 100 s integration time constant. The radiometers, optimized for ac measurements, were tested in a dc measurement mode as well. Performances in ac and dc measurement modes were compared. In the ac mode, a ten times shorter (40 s) overall measurement time was needed than in the dc mode (400 s) to obtain the same 10(-16) A noise floor.

Design of wideband low noise transimpedance amplifiers for optical communications

Abstract: Most optical communication receivers employ common-emitter (BJT) configuration for the transimpedance preamplifier. In this paper the common-base regulated cascode and common-emitter preamplifiers are compared in terms of low-noise and wide-band performances. The effect of capacitive and inductive peaking techniques on bandwidth and noise has been investigated for the two circuits. PSPICE simulations showed that both methods resulted in significant bandwidth extension for both circuits. The common-base preamplifier low input impedance resulted in more efficient use of the peaking methods by requiring lower capacitor and inductor values.

Triggered receivers for optoelectronic VLSI

Abstract: A ‘triggered’ transimpedance digital optical receiver is described which is usable in noisy environments typical of dense mixed-signal circuits. Results show enhanced immunity to supply variations compared to conventional transimpedance receivers.

Circuit having dual feedback multipliers

Abstract: An analog multiplier circuit utilizes a dual feedback structure, in which two multiplier core sections can be progressively enabled or disabled to varying degrees, thereby providing variable gain while maintaining constant bandwidth. The multipliers are preferably controlled by a pair of ratiometric gain control signals in a manner that provides very accurate end-point gain. A summing device combines the outputs from the multipliers to generate a final output signal that is buffered and fed back to the multipliers through two separate feedback paths. The circuit can operate as a video keyer that linearly selects between two input signals applied to the multipliers. Alternatively, the circuit can be operated as a variable gain amplifier (two quadrant multiplier) when one of the two inputs is not used. Each of the multipliers is preferably implemented with sets of differential transistor pairs having complementary symmetry and a Class AB current conveyor input. The outputs of the multipliers can be coupled to a transimpedance node through current mirrors, thereby providing push-pull drive that is free of slew-rate limitations.

Low voltage differential amplifier with high voltage protection

Abstract: An apparatus comprising a native device coupled to an input of an amplifier. The native device is configured to provide a high voltage protection in response to an enable signal.

Direct optical fm discriminator

Abstract: A method and apparatus for optical frequency modulation discrimination. An optical beam is split into a first optical beam and a second optical beam. A first photodetector is provided, the first photodetector providing a first current responsive to the first optical beam input thereon, the first photodetector having a first photodetector spectral response and being biased such that the first current is in a first direction. A second photodetector is also provided, the second photodetector providing a second current responsive to the second optical beam input thereon,the second photodetector having a second photodetector spectral response and being biased such that the second current is in the first direction. An input of a transimpedance amplifier is coupled to an output of the first photodetector and to an input of the second photodetector to provide an output of the transimpedance amplifier proportional to the difference between the first current and the second current. A first optical filter is provided to receive the first optical beam prior to incidence upon the first photodetector and a second optical filter to receive the second optical beam prior to incidence upon the second photodetector, wherein the first photodetector spectral response and the second photodetector spectral response are each broader than respective passbands of the first optical filter and the second optical filter to provide photocurrent vs. optical frequency characteristics determined by the respective first optical filter and the second optical filter.

Low-offset BiCMOS OEIC for optical storage systems

Abstract: A BiCMOS optoelectronic integrated circuit (OEIC) for optical storage systems containing photodiodes and transimpedance amplifiers with a reduced offset voltage is presented. A reference transimpedance amplifier and a low-offset operational amplifier are implemented for offset reduction. A -3 dB frequency of 58 MHz and a sensitivity of 25 mV//spl mu/W at 638 nm have been measured.

A 1.2 V bandgap reference based on transimpedance amplifier

Abstract: For practical implementation of a typical bandgap reference, the minimum supply voltage is usually over 1.8 V mainly due to the limited input common mode range of the opamp used in the bandgap reference. In this paper, a low voltage bandgap reference using a transimpedance amplifier that does not have this limitation is proposed. Based on this technique, a 1.2 V bandgap reference was implemented in a 1.2 /spl mu/m CMOS process (V/sub TN//spl ap/0.53 V and V/sub TP//spl ap/-0.91 V) with bipolar option. The variations of the output voltage over temperature (0/spl deg/C/spl les/T/spl les/100/spl deg/C) were measured to be less than /spl plusmn/1% without resistor trimming.

Unified analytical expressions for transimpedance and equivalent input noise current of optical receivers

Abstract: Unified analytical expressions are derived for calculating the equivalent input noise current and transimpedance of optical receiver front ends with arbitrary input matching network topologies. To be independent of any transistor or amplifier type, noise parameters are used to describe the noise behavior of the active device. A new characteristic frequency-dependent value, called photodiode intrinsic conductance, is introduced. This figure-of-merit allows one to compare the achievable equivalent input noise current and transimpedance of different types of photodiodes independently of amplifier type and geometry.

A receiver channel with a leading edge timing discriminator for a pulsed time-of-flight laser radar

Abstract: An integrated receiver channel with a wide dynamic range for a pulsed time-of-flight (TOF) laser rangefinder has been designed and tested. The circuit uses leading edge timing discrimination. The bandwidth of the receiver channel is 250 MHz and the maximum transimpedance 40 kΩ. The single-shot distance measurement accuracy is 65 mm, taking into account walk error (input signal amplitude varies in the range from 1 to 4000) and jitter (+/-3σ).