Common-base Configuration Research Articles

Experimental and theoretical study of the current-voltage characteristics of the MISIM tunnel transistor

Current-voltage (I-V) characteristics of the metal-insulator-semiconductor-insulator-metal (MISIM) tunnel transistor in the common base and common emitter configurations are studied experimentally and theoretically. The Al-SiO/sub 2/-Si(n)-SiO/sub 2/-Al transistors with oxide layers of about 2.5 nm thickness have been manufactured. The devices exhibit current gain above 30 in the common base configuration and switching in the common emitter configuration. A theoretical static model of the MISIM tunnel transistor has been developed and applied to analyze the measured I-V characteristics for both operation configurations. Excellent fit of the model to the experimental data has been achieved. Influence of oxide thickness and interface trap density on the switching voltage has been investigated theoretically.

Class-A SiGe HBT power amplifiers at C-band frequencies

In this letter we report on the first experimental investigations of the power-handling capabilities of SiGe heterojunction bipolar transistors (HBT's) at C-band frequencies. Multifinger HBT's in common-emitter (CE) and common-base (CB) configuration were matched using high Q matching networks. At a frequency of 5.7 GHz the CE and the CB class A amplifier exhibit a 1-dB compression output power of 18 and 20 dBm, respectively. A power-added efficiency (PAE) of more than 30% and a output power density of 1 mW//spl mu/m/sup 2/ at 4 V V/sub CB/ were observed.

Novel fabrication of self-aligned [formula omitted] and [formula omitted] microwave power heterojunction bipolar transistors

Self-aligned processing of high efficiency power heterojunction bipolar transistors (HBTs) using implant isolation, selective wet and dry etching for mesa formation, plasma-enhanced chemical vapor deposited SiN x for sidewall spacers and through-wafer via connections is reported. GaAs AlGaAs and GaAs InGaP HBTs were grown by Metal Organic Molecular Beam Epitaxy utilizing carbon for high, well-confined base doping and tin for n-type doping to reduce emitter contact resistance. GaAs AlGaAs HBTs with twelve 2 × 15 μm 2 double-emitter finger devices produced power-added efficiencies of 63%, power gain of 10 dB and output power of 1.7 W at 4 GHz. The results of power measurements at 4–12 GHz for GaAs InGaP HBTs with common emitter and common base configuration are also reported.

Dynamic characterisation of Si/SiGe power HBTs

Si/SiGe power heterojunction bipolar transistors (HBTs) grown by MBE were dynamically characterised in the common-base configuration. At an emitter current density of 1.1*10/sup 5/ A/cm/sup 2/, a maximum frequency of oscillation of 49 GHz was observed. At 10 GHz a maximum unilateral gain of 14 dB is available, and a CW output power of 1.3 W/mm for a device with 10 parallel emitter-fingers of 1*10 mu m/sup 2/ each was predicted, from CW measurements.

Polarisation-agile active patch antenna

A polarisation-agile active antenna has been constructed and tested. The radiation can be selected to be circularly polarised in either sense, or linearly polarised in the vertical, horizontal or either diagonal plane. The antenna consists of two varactor diode loaded active patches using npn bipolar transistors in the common base configuration as sources, and with the patch axes at right angles to each other. The two oscillators are locked to an external source, and the phase from each patch element is controlled by varying the diode bias voltage. By appropriate combination of the phase relationships, the various polarisations are produced.

Room-temperature operation of InGaAs-based hot-electron transistors

It is demonstrated that 300-K operation of an InGaAs-based HET (hot-electron transistor) can be achieved by further increasing the electron injection energy in combination with the use of a wide-bandgap base-collector isolation barrier. The characteristics of a device consisting of an InAlAs emitter, a 10-AA AlAs tunnel-barrier positioned at the emitter-base heterojunction, a 400-AA n+ InGaAs base region, and a 2500-AA InAlGaAs collector barrier are reported. The injected electrons are transported across the base region with over 80% efficiency, as measured in a common-base configuration. The maximum common-emitter current gain in this nonoptimized transistor is nearly four with an f/sub T/ of over 40 GHz and a base-collector breakdown voltage of 1.5 V. A systematic study of RHET (resonant tunneling HET) injector and collection properties indicates that the HET can operate at room temperature with a current gain on the order of 100. 300-K operation of a single-RHET, exclusive-NOR integrated circuit that is similar in design to the one demonstrated at 77 K by N. Yokoyama et al. (1985) is also shown.

Comments, with reply, on "AlGaAs/GaAs HBT for high-temperature application" by K. Fricke et al

The commenter discusses several aspects of the above-titled work by K. Fricke et al. (ibid., vol. 39, pp. 1977-1981, Sept. 1992). These concern the physics of the saturation in an HBT and the collector leakage current. In their reply, to demonstrate the second effect, Fricke et al. report that the collector leakage current at different ambient temperatures was measured in common base configuration. They discuss the influence of the hole leakage current on the base current.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Metal base transistor of In/Bi(Ba,Rb)O/sub 3//SrTiO/sub 3/ (Nb)

A metal-base transistor of the MOMOM type with large current gain is reported. It uses Bi(Ba,Rb)O/sub 3/ and oxide semiconductors. I-V curves for a Bi(Ba,Rb)O/sub 3/ base transistor in the common-base configuration were studied from room temperature to 30 K. Current gain alpha approximately 1 was obtained at 50 K. Transport behavior is determined by analysis of threshold voltages and derivatives dI/sub c//dV/sub cb/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

On the design of low-noise current-mode optical preamplifiers

Classical designs of optical transimpedance amplifiers for p-i-n photodiode receiver circuits generally employ common-emitter or common-source input stages. In this paper we explore the design of a new class of low-noise “current-mode” optical preamplifier based upon common-base and common-gate input stages. Two current-mode designs are considered, firstly an improved bipolar common-base configuration and secondly a GaAs MESFET common-gate configuration. Both designs employ current-feedback techniques to achieve higher transimpedance gains than is obtained with classical voltage-feedback structures for the same operating bandwidth. A theoretical noise analysis of the new current-mode designs confirms the expected low noise performance. Finally, experimental noise measurements at 100-MHz bandwidth indicates that under certain conditions electrical noise improvements of up to 4 dBs over classical designs can be obtained with the new current-mode circuits.

Active patch antenna element with diode tuning

Active patch antennas incorporating Schottky diodes used as tuning devices have been constructed and tested. npn bipolar transistors operating in the common-base configuration are employed as sources, and the antenna itself is a multilayer structure which enables isolation of the diode biasing circuitry from the transistor circuitry, while being inherently wideband, and capable of realising desirable radiation patterns. Tuning ranges of up to around 100 MHz at 2.2 GHz (4.4%) have been obtained, with good radiation patterns over the entire frequency range.

Rotation of base region hall field in magnetotransistors

We present measurement results of Hall field rotation in the base region of npn lateral magnetotransistors operated in common base configuration at various emitter currents. The measured Hall voltages are small ( V H ∼μV) and the direction of the corresponding Hall field progressively rotates with increasing collector bias voltages, V CB . In terms of device parameters, the Hall fields were found to behave in the following manner. In the regime where the common base current gain h FB <1, the Hall field is relatively large (due to the high base current) and is mainly due to majority carriers. Beyond a certain critical V CB where h FB ⩾1, the Hall field saturates to some finite value for a given emitter current and is opposite in direction. Its Hall coefficient is opposite in sign and is due to the excess minority charge injected into the base (n ≳ p). The switch in sign happens where h FB ≲ 1 when n ≳ p (μ p */μ n *) 2 in the base region.

Hybrid Pi common base analysis

A high-frequency analysis of the bipolar common base configuration is developed with particular application to the design of low-input-impedance optical fiber receivers tolerant of source capacitance. The results show dependence on transistor type and operating parameters, indicating that careful choices may be necessary for optimum performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The complementary Darlington-a novel current source for ICs

Compared with the performance of a single transistor operating in the common-base configuration, the complementary Darlington can be considered as a three-terminal device whose current gain and output resistance are both increased by a factor equal to the beta of the complementary transistor, and whose partition noise is dominated by the base current of the latter. The circuit operation is based on positive feedback, but stability is unconditional since the loop transmission LT<<1.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Noise parameter transformations for three-terminal amplifiers

The common-emitter noise parameters and z parameters for a transistor (or any three-terminal amplifier) are used to obtain the corresponding sets of noise parameters for the common-base and common-collector configurations. It is shown that the three configurations must have the same minimum noise measure. A practical example is presented to confirm this invariance. High-gain amplifiers with the minimum noise figure can be built with any of the three configurations of combinations thereof. The choice of configuration is determined by factors such as ease of stabilization or bandwidth.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Miniband conduction of minority electrons and negative transconductance by quantum reflection in a superlattice transistor

Transport of electrons tunnel injected into a superlattice (SL) is studied. The SL is placed in the base of an n-p-n bipolar transistor. By varying the emitter-base forward bias (VEB), the energy of electrons injected into the base is varied. From the emitter and collector current measurements in the common-base configuration, it is found that the electron transmission to the collector is strongly dependent on the injection energy, the currents showing a sharp peak, and the associated negative transconductance. The measurements show excellent agreement with the calculated values of VEB at the onset of miniband conduction and at the suppression of injection into the SL due to enhanced quantum reflection by the SL minigap. The transfer characteristics also reveal a low-current gain regime of electron transport below the onset of miniband conduction, implying conduction mediated by subminiband gap states.

Transimpedance optical preamplifier with a very low input resistance

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.

One-dimensional three-terminal thyristor modelling at high current densities and stable common gate configuration

One-dimensional modelling of a thyristor, in common base (gate) configuration and the absence of ohmic base resistance removed the inherent instability of the device and enabled the variation of current gains of the constituent transistors to be calculated to very high current densities in conjunction with a host of other parameters. The model employs a Gaussian impurity profile coupled with a combined SRH and Auger recombination term and includes variable mobilities (impurity and c- c scattering as well as electric field dependence). Reverse bias across the central junction of up to 20 V offered no undue difficulties in modelling. The high current flow in excess of recombination requirements in the base regions was rendered harmless by being allowed to pass unhindered out of the gate terminal. This resulted in the anode current exceeding numerically the cathode current with the sum of d.c. current gains having crossed what under different configurations would constitute an instability threshold.

Time domain noise calculation for the common base current amplifier configuration

Abstract An analysis is presented of the behaviour of the common base configuration current amplifier. Some noise relations are developed taking into account the noise generated in the first and second stage of the amplifier. Simplified expressions for the equivalent noise charge are given in order to be able to determine the noise contribution from various circuit components.

The structure of some refractory transition metal-metalloid glasses

The radial distribution functions of four refractory alloys of composition (W 0.5Ru 0.5) 0.8 M 0.2 where M = some metalloid from the group B, P, Al 0.5B 0.5, Si 0.5B 0.5 are presented along with densities, atomic volumes of metalloids and coordination numbers. The atomic distributions functions of these materials have been found to exhibit characteristics typical of many other amorphous metal-metalloid alloys. A comparison was made between the experimentally determined distribution functions for the WRu alloys and the Bernal Finney model calculations of dense random packings of hard spheres using the average WRu Gold-schmidt radii as the hard sphere radius. The agreement was found to be quite good in nearly all places, the most notable exception being in the vicinity of the second maxima, where the relative heights of the double peaks is found to be different from the DRPHS for the cases of M = B, P and B 0.5Si 0.5. In all cases for the WRu alloys the reduced radial distribution functions suggest a local short range order favoring common-base tetrahedra configurations as opposed to coplanar tetrahedra bases predominant in the DRPHS.

Properties of the super-alpha composite transistor at high frequencies

The equivalent circuit of the composite transistor, the input impedance and the current gain have been developed by analysing its equivalent circuit, in terms of the various parameters of the individual transistors in the common base and common emitter configuration. It is found that in the C.E. configuration, the short-circuit input impedance hie has a negative resistance component over a frequency range in which the current gain in the C.B. configuration h/b is greater than 1.