Darlington Configuration Research Articles

Lateral bipolar junction transistor on a silicon photonics platform.

Integration of active electronics into photonic systems is necessary for large-scale photonic integration. While heterogeneous integration leverages high-performance electronics, a monolithic scheme can coexist by aiding the electronic processing, improving overall efficiency. We report a lateral bipolar junction transistor on a commercial silicon photonics foundry process. We achieved a DC current gain of 10 with a Darlington configuration, and using measured S-parameters for a single BJT, the available AC gain was at least 3dB for signal frequencies up to 1.1 GHz. Our single BJT demonstrated a transimpedance of 3.2mS/μm, which is about 70 times better than existing literature.

A comparative experimental investigation on responsivity and response speed of photo-diode and photo-BJT structures integrated in a low-cost standard CMOS process

A variety of smart imaging and neuromorphic applications perform time-domain image acquisition in order to imitate biological systems and reduce the growing transmission bandwidth of the modern imaging devices. Because they operate in time-domain, they require the highest possible pixel responsivity and response speed. This work provides a comparative experimental study of different unconventional photodetecting structures with respect to these parameters. Several on-chip photodetecting device structures are designed using a low-cost standard 0.18μm CMOS process. The comparison in terms of measured quantum efficiency, light responsivity and the response speed is presented between conventional and comb-shaped N-well/P-substrate photodiodes, conventional and comb-shaped, vertical and lateral photo-bipolar-junction-transistors (photo-BJTs) and a Darlington pair of bipolar-junction phototransistors. The photodetectors are embedded in a conventional three transistor active pixel topology and measured using a customized low-cost measurement setup. The pixel quantum efficiency, responsivity and response speed are measured for each structure and the results are presented in detail. The obtained results demonstrate the benefits of using standard-CMOS-compatible BJT structures in time-domain applications. The BJT-based photodetectors show increased responsivity to green–yellow light region (500–600nm wavelength) compared to conventional N-well/P-substrate diode. The highest responsivity is achieved by a combination of lateral and vertical BJT. The fastest response is achieved by the rarely used Darlington pair configuration of BJTs, which demonstrates the potential benefit of using this structure for time-domain imaging applications. A low-cost measurement setup and the measurement methodology are described in detail to make the experiment reproducible for any other standard CMOS process.

An X-Ray Detector Using a Fluorescent Material ZnS:Ag Attached on a Phototransistor in Darlington Configuration

X-rays have been widely used in medical imaging system. CT Scan is one of the important diagnostic equipments in medical field that uses X-rays as a probe. In the latest CT-Scan generation an array of X-ray detector in a gantry is employed. Solid state detector and gas filled detector are currently used. These type of detector have relatively large in physical size. This influenses the size of the machine as well as its performance. In order to obtain an X-ray detector in a small size a phototransistor was exploited. The phototransistor was attached on a fluoroscent screen and arranged in Darlington configuration. The phototransistor in Darlington configuration was calibrated using visible light. The results showed that there was a linear correlation between the phototransistor output (mV) and the light intensity impinging on the phototransistor surface. A fluoroscent material (ZnS:Ag) then attached on the phototransistor surface. They work as an X-ray detector and calibrated using an X-ray beam generated from an X-ray machine. The results also confirmed that there was a linear correlation between the detector output (mV) and the X-ray intensity stricking the detector surface. The active area of the detector was explored by scanning the surface of the detector in vertical as well as in horizontal directions. The effective diameter of the active area of the detector was found to be 2.2 mm.

A Novel Circuit Model of Small-Signal Amplifier using MOSFETs and BJT in Quadruple Darlington Configuration

circuit model of a small-signal narrow-band amplifier is proposed. The Proposed amplifier is designed using three MOSFETs and a BJT in quadruple Darlington configuration. The proposed circuit successfully amplifies small-signals of 1-10mV range and simultaneously provides high voltage gain and current gain with narrow bandwidth. In this way the proposed design achieved excellent results. Qualitative performance of the proposed amplifier is also compared with the circuit which is having BJT-MOSFET in Darlington pair configuration and with the circuit which is having BJT-MOSFETs in Darlington triple configuration. The proposed amplifier can be used to process audio range signal excursions and may be useful for those applications where high voltage and current gain would be the prime requirement of amplification in narrow-band low frequency region. The qualitative and tuning performance offer a flexible application to these amplifiers to be used as high voltage gain, high power gain and tuned amplifiers. .

Design of Low Voltage, Low Power (IF) Amplifier Based-On MOSFET Darlington Configuration

This paper presents a different approach of Intermediate Frequency (IF) amplifier using 0.18 μm MIETEC technology channel length of MOSFET Darlington transistors. In contrast to Bipolar conventional Darlingtonpair, a MOSFET Darlington configuration is employed to reduce supply voltage (VDD) and DC consumption power (Pc). The frequency response parameters of the proposed design such as bandwidth, gain bandwidth product, input/output noises and noise figure (NF) are improved in proposed (IF) amplifier. Moreover, a dual-input and dual-output (DIDO) IF amplifier constructed from two symmetrical single input and single output (SISO) (IF) amplifier is proposed too. The idea is to achieve improved bandwidth, and flat response, because these parameters are very important in high frequency applications. Simulation results that obtained by P-SPICE program are 1.2 GHz Bandwidth (BW), 3.4 GHz (gain bandwidth product), 0.5 mW DC consumption power (Pc) and the low total output noise is 12 nV with 1.2 V single supply voltage.

In defense of discrete features

A major challenge for discrete feature theories of speech perception is that the acoustic signal is continuously changing within and between segments at a high rate. These theories must explain how continuously changing spectral patterns are perceived as discrete and independent features. This problem does not disappear after auditory transformations of the acoustic signal, since temporal and frequency resolution, despite being coarse, still preserve most of the signal dynamics. In this work, it is shown that if articulatory features are extracted from the continuously changing acoustic signal, assuming that the signal is the output of a lossless vocal tract terminated in a unit resistance, i.e., a Darlington configuration (Iskarous, Journal of Phonetics, 2010), it is possible to obtain a discretely changing place of articulation feature from the continuous signal change. This will be illustrated using articulatory inversion of VV and CV transitions from the X-ray microbeam database for five male and five female participants. This work supports theories of discrete and independent perceptual features, as assumed for instance by Miller and Nicely (1955), if the acoustic signal is interpreted in terms of the vocal tract actions that cause it (Goldstein and Fowler, 2003).

Design of a Latchup-Free ESD Power Clamp for Smart Power ICs

A latchup-free design based on the lateral diffused MOS (LDMOS) adopting the approaches was designed. The use of Darlington configuration as the trigger circuit results in the reduction of the size of the circuit when compared to the conventional inverter driven RC-triggered MOSFET ESD power clamp circuits. The proposed clamp was fabricated using a 0.35 μm 60V BCD (Bipolar CMOS DMOS) process and the performance of the proposed clamp was successfully verified by TLP (Transmission Line Pulsing) measurements.

Silicon germanium heterojunction bipolar transistor electrostatic discharge power clamps and the Johnson Limit in RF BICMOS SiGe technology

Achieving radio frequency (RF) performance circuit objectives and electrostatic discharge (ESD) protection will continue to challenge future technology. In this study, we use the ultimate limitation of the transistor (known as the Johnson Limit) as a means to provide an ESD power clamp by utilizing a first low breakdown trigger device and a second high breakdown clamp device. Using the inverse relationship between unity current gain cutoff frequency and breakdown voltage, ESD power clamps are constructed using epitaxial base pseudomorphic silicon germanium (SiGe) heterojunction bipolar transistors in a common-collector Darlington configuration. ESD experimental test results from human body model (HBM), machine model (MM) and transmission line pulse (TLP) testing demonstrate the scaling of ESD power clamps. Design studies of alternative implementations, resistor ballasting and different trigger transistors will be discussed. As a comparative analysis, the SiGe-based ESD power clamps will be compared to CMOS MOSFET-based ESD power clamps. A new dimensionless group is defined to quantify the relationship between the power-to-failure and the maximum power. Additionally, a future SiGe technology is shown to provide insight into the impact of technology scaling on future SiGe ESD power clamps.

Characterization of high-density current stressed IGBTs and simulation with an adapted SPICE sub-circuit

Insulated Gate Bipolar Transistors are devices integrating a MOSFET and a bipolar transistor in a Darlington configuration. These devices have been studied before and after conduction stress. During high temperature operations (200°C) hot carriers can induce degradation in gate oxide, at silicon–oxide interface and into the base–emitter junction. The used IGBT SPICE sub-circuit can describe electrical aging in dynamic and static operation. The knowledge of which parameters are influenced during specific functional stress permits us to compensate for these changes or improve the implementation of the component in a circuit, as well as its use in field conditions.

Broadband feedback amplifiers withAlInAs/GaInAs transferred-substrate HBT

Broadband amplifiers with AlInAs/GaInAs transferred-substrate heterojunction bipolar transistors (HBTs) are described. A simple Darlington configuration with resistive feedback has 50 GHz 3 dB bandwidth and 10 dB gain. This high bandwidth results from the high device bandwidth of transferred-substrate HBTs fabricated in an IC process.

Application of complementary techniques to a bipolar translinear gain cell and a translinear CCII+

A multistage translinear amplifier is described, employing complementary techniques. The input cell includes a common mode rejection circuit, which maintains the push-pull output if a single ended input is applied without affecting the performance. Another example describes a translinear CCII+ employing an input Buffer, whose current transfer function is practically one due to the Darlington configuration employed. Finally, this CCII+ is employed as output stage for an inverting current amplifier.

Hybrid MOS-bipolar transistor switching with profiled drive signal

A method for switching MOS-bipolar transistor hybrids has been developed, which improves the transition performance and minimises the base drive power requirements in a split Darlington configuration with low on-state voltage. The type of wave shaping of the input control signal, enables unusually small and high speed MOSFETs to drive exceptionally high base current pulses for fast turn-on of a bipolar power transistor. Since bipolar over-saturation is avoided, the turn-off is also improved.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Integrated complementary HBT microwave push-pull and Darlington amplifiers with p-n-p active loads

The authors report the microwave results of complementary heterojunction bipolar transistor (HBT) amplifiers that integrate both n-p-n and p-n-p devices on the same chip using selective molecular beam epitaxy (MBE). An HBT wideband amplifier utilizing the Darlington configuration and implementing a p-n-p active load has a gain of 7.5 dB and a bandwidth from DC to 2.5 GHz. A complementary push-pull amplifier has a saturated output power of 7.5 dBm at 2.5 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An optically controllable negative resistance circuit constructed with optocouplers

An optocoupler with a Darlington configuration at the output side can be used as a one port active device with a current-controlled negative resistance by simply connecting the input and output sides in cascade. The author proposes an optically controllable negative-resistance circuit constructed with optocouplers. The breakover voltage and the holding current of the negative-resistance characteristics can be controlled widely with two external light inputs. Hence, the circuit may be applied to optronic functional switching operations. It is demonstrated that an optically controlled relaxation oscillator can be easily constructed using the circuit, and that applications of the relaxation oscillator to a light modulator and an optical Schmitt trigger can be realized by simple circuit configurations.

Behavior of the n-stage Darlington configuration

The input impedance of a n- stage Darlington configuration is analyzed by using the hybrid-II equivalent circuit. Instability arise for n ≥ 2 as a result of real part being negative at some frequencies. A single transistor can also be made to oscillate by connecting an external capacitor between emitter and ground.