HBT Model Research Articles

Deep Neural Network RF Model for SiGe HBT in Breakdown Regime

Deep Neural Network RF Model for SiGe HBT in Breakdown Regime

Two-dimensional elasticity model for composite beams with deformable shear connectors: Analytical and numerical solutions

A novel and efficient exact two-dimensional (2D) model is developed for predicting the flexural response of two-layered composite beams made of different materials based on the elasticity theory. The beam is considered as a specific case of plane stress problem laying in the longitudinal vertical plane passing through the centroid of the beam section. The proposed two-dimensional model considers the orthotropic properties of materials used in composite beams. The partial shear interaction between two material layers in the form of shear slip at their interface is also considered in this study. The deformable shear connectors between these layers are modeled using distributed shear springs along the beam length. The present 2D model's accuracy is validated by comparing its results with published results as well as numerical results generated by a thorough 2D finite element model using ABAQUS. Furthermore, the stretching effect over the direction of beam depth on the flexural response of two-layered composite beams is investigated by comparing the results produced by the one-dimensional (1D) HBT model and the proposed 2D elasticity model.

A complete small-signal HBT model including AC current crowding effect

An improved small-signal equivalent circuit of HBT concerning the AC current crowding effect is proposed in this paper. AC current crowding effect is modeled as a parallel RC circuit composed of C bi and R bi, with distributed base-collector junction capacitance also taken into account. The intrinsic portion is taken as a whole and extracted directly from the measured S-parameters in the whole frequency range of operation without any special test structures. An HBT device with a 2 × 20 μm2 emitter-area under three different biases were used to demonstrate the extraction and verify the accuracy of the equivalent circuit.

Sensitivity analysis and uncertainty estimation in small‐signal modeling forInP HBT(invited paper)

AbstractIn this paper, a sensitivity analysis and uncertainty estimation of small‐signal model for InP HBT is presented. Analytical expressions for sensitivity are derived in terms of the measured S‐parameters based on the direct intrinsic parameters extraction. Furthermore, the uncertainties of the intrinsic parameters vs frequency are discussed to give more reliable extraction results. The optimal solutions of the parameters are obtained by utilizing sensitivity analysis. In the frequency range of 45 MHz‐40GHz, good fits between the measured and modeled S‐parameters are achieved for 5 × 5μm2InP HBT.

Proton-induced current transient in SiGe HBT and charge collection model based on Monte Carlo simulation

The study presents an investigation into the proton-induced current transient in a silicon-germanium heterojunction bipolar transistor (SiGe HBT). The temporal information of the proton-induced current transients is first measured and then compared with results from heavy ion microbeam experiment. Additionally, a model for proton-induced charge collection based on Geant4 Monte Carlo simulation tools is constructed by using the information from heavy ion experiment and 3D TCAD simulation. The results obtained by the validated model exhibit good consistency with the proton experiment.

An Improved Small-Signal Model for SiGe HBT Under OFF-State, Derived From Distributed Network and Corresponding Model Parameter Extraction

An improved high-frequency small-signal model for SiGe HBTs under the off-state is presented in this paper. The proposed model takes into account the distribution characteristics of the intrinsic transistor, link base region under spacer, and extrinsic base–collector junction. The equivalent circuit for each region is separately derived using the transmission line equation with reasonable approximations. Being different from previous models, the intrinsic base resistance in the proposed model is pushed inside the internal base node and added to the components of collector and emitter resistance. To extract all the parameters for the proposed model, a novel extraction technique based on rational function fitting over the whole range of frequencies is developed. After the rational function fitting to related admittance parameters, a number of coefficients are accurately obtained and then all the model parameters are directly extracted without any special test structure or numerical optimization. The proposed model and extraction technique are validated with a series of sized SiGe HBTs from 100 MHz to 20.89 GHz at a wide range of bias points. An excellent agreement is obtained between the measured and simulated S-parameters.

K Band SiGe HBT single ended active inductors

The study of monolithic integration of active inductors (AI) on a 0.25μm SiGe BiCMOS technology with 4 metal layers and HBTs with fT=120GHz is presented. Two topologies are presented and their performance discussed. Q values higher than 30 were obtained on a 3.4GHz bandwidth at 28GHz and maximum values as high as 100. Active inductors can be biased with low power, such as 2V with a nominal DC current of 0.6mA. The inductance value is controlled by external bias voltages and adjustments up to 40% were measured. Simple gyrators topologies with only 2 transistors are used for low power consumption and good performance at K Band is proved. The internal parameters of small signal model of HBT were studied and the crucial parameter to enhance the negative resistance and so the Q of the AI was identified.

Frequency stability of InP HBT over 0.2 to 220 GHz

The frequency stabilities of InP DHBTs in a broadband over 1 to 220 GHz are investigated. A hybrid π-topology small-signal model is used to accurately capture the parasitics of devices. The model parameters are extracted from measurements analytically. The investigation results show that the excellent agreement between the measured and simulated data is obtained in the frequency range 200 MHz to 220 GHz. The dominant parameters of the π-topology model, bias conditions and emitter area have significant effects on the stability factor K. The HBT model can be unconditionally stable by reasonable selection of the proper bias condition and the physical layout of the device.

On the Transient Response of a Complementary (npn <formula formulatype="inline"><tex Notation="TeX">$+$</tex></formula> pnp) SiGe HBT BiCMOS Technology

The single-event transient (SET) response of a third-generation bulk C-SiGe ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\hbox {npn}} + {\hbox {pnp}}$</tex></formula> ) BiCMOS platform is investigated for the first time. Pulsed-laser, two-photon absorption experiments show that the pnp SiGe heterojunction bipolar transistor (SiGe HBT) exhibits a significant reduction in sensitive area as well as an improved transient response compared with the npn SiGe HBT. Ion-strike simulations on 3-D TCAD, C-SiGe HBT models agree with experimental findings, showing a reduction in overall transient duration and collected charge for the pnp SiGe HBT. These improvements in device-level SETs are attributed to the n-well isolation layer present in the vertical material stack of the pnp HBT. These results suggest that precision analog, RF/mm-wave, and high-speed digital applications utilizing unhardened, high-performance bulk pnp SiGe HBTs should benefit from an inherently improved SEE response.

An Investigation of Single-Event Effects and Potential SEU Mitigation Strategies in Fourth-Generation, 90 nm SiGe BiCMOS

The single-event effect sensitivity of fourth-generation, 90 nm SiGe HBTs is investigated. Inverse-mode, ≥1.0 Gbps SiGe digital logic using standard, unoptimized, fourth-generation SiGe HBTs is demonstrated and the inverse-mode shift register exhibited a reduction in bit-error cross section across all ion-strike LETs. Ion-strike simulations on dc calibrated, 3-D TCAD SiGe HBT models show a reduction in peak current transient magnitude and a reduction in overall transient duration for bulk SiGe HBTs operating in inverse mode. These improvements in device-level SETs are attributed to the electrical isolation of the physical emitter from the subcollector-substrate junction and the high doping in the SiGe HBT base and emitter, suggesting that SiGe BiCMOS technology scaling will drive further improvements in inverse-mode device and circuit-level SEE. Two-photon absorption experiments at NRL support the transient mechanisms described in the device-level TCAD simulations. Fully-coupled mixed-mode simulations predict large improvements in circuit-level SEU for inverse-mode SiGe HBTs in multi-Gbps, inverse-mode digital logic.

Analytical study of substrate parasitic effects in common-base and common-emitter SiGe BHT amplifiers

An analytical study to quantify the substrate parasitic effects on SiGe HBT amplifiers in both common-base and common-emitter configuration is presented. The power gain relations and stability factors are derived from the modelled S-parameters which are computed at a fixed bias point from the small-signal hybrid-∏ model of SiGe HBT in both configurations. It has been shown that the power gains of SiGe HBT amplifiers in both configurations are degraded when extrinsic and substrate parasitics are taken into account. The degradation in power gains is found to be more pronounced for CB configuration, which makes the design of HBT amplifiers, particularly in the CB mode, difficult. Close matching of the modelled data with the reported experimental results validates the proposed methodology.

Sensitivity of narrow- and wideband LNA performance to individual transistor model parameters

Although it is desirable for a transistor model to be as accurate as possible, the extraction of model parameters from fabricated transistors is a time-consuming and often costly process. An investigation of the sensitivity of low-noise amplifier (LNA) performance characteristics to individual parameters of the physics-based standard HBT model HICUM/L2 was, therefore, done to gain a preliminary insight into the most important parameters for transistors used in actual circuits. This can potentially allow less strenuous accuracy requirements on some parameters which would ease the extraction process. Both a narrow- and wideband LNA configuration were investigated. It was found that the series resistance parameters have a large impact on LNA gain, S 11 and noise figure performance in both cases. Since the narrow-band LNA relied heavily on the transistor characteristics to provide a proper matching, it was also very sensitive to changes in the parameters used in modelling the high-frequency current gain and depletion capacitances of the transistor.

Predictive Physics-Based TCAD Modeling of the Mixed-Mode Degradation Mechanism in SiGe HBTs

We study mixed-mode stress degradation in SiGe HBTs using a novel physical TCAD model in which the processes of hot carrier generation within the semiconductor, carrier propagation to the oxide interface, and formation of interface traps are directly modeled. Transient degradation simulations using a calibrated 2-D SiGe HBT model correlate well with measured data. With this novel simulation tool, we investigate the bias dependence and location of interface traps and show that secondary holes produced by impact ionization are the dominant carrier to damage the emitter-base (EB) spacer oxide interface, confirming previously reported results. We also compare in detail trap formation at the EB spacer and shallow-trench-isolation (STI) oxide interfaces as a function of time and stress condition. At the STI oxide interfaces, we find that hot electrons and holes each dominate trap formation in different regions, and the hot carriers that reach the STI predominately originate outside of the selectively implanted collector, revealing the important role played by dopant diffusion from the extrinsic base of quasi-self-aligned SiGe HBTs.

Study of Molecular Interactions in Binary Mixtures of Aniline with Carboxylic Acids at 293.15 K, 303.15 K and 313.15 K

Ultrasonic velocity, density, refractive index and viscosity of binary mixtures of aniline with acetic acid (AA) and propionic acid (PA) have been measured at 293.15, 303.15 and 313.15 K over the entire composition range. Further, the specific heat ratio, heat capacity, effective Debye temperature and pseudo-Gruensisen parameter and non-linearity parameter have been evaluated using ultrasonic absorption data. The deviation in isentropic compressibility, excess molar volume, excess intermolecular free length, deviation in molar refraction, deviation in viscosity, relaxation time, enthalpy, entropy and Gibbs energy of activation have been calculated from the experimental data and fitted with the Redlich-Kister polynomial equation. A comparative study has also been made between experimental and theoretically calculated values of densities using the HBT and Rackett density models. Mixing rules for the prediction of refractive index, e.g. Lorentz-Lorenz (L-L), Eykmen (Eyk), Weiner (W), Heller (H), Gladstone-Dale (G-D), Arago-Biot (A-B) and Newton (N) have been applied to these binary mixtures.

0.13 $\mu$m SiGe BiCMOS Technology Fully Dedicated to mm-Wave Applications

This paper presents a complete 0.13 μm SiGe BiCMOS technology fully dedicated to millimeter-wave applications, including a high-speed (230/280 GHz fT/fMAX) and medium voltage SiGe HBT, thick-copper back-end designed for high performance transmission lines and inductors, 2 fF/μm2 high-linearity MIM capacitor and complementary double gate oxide MOS transistors. Details are given on HBT integration, reliability and models as well as on back-end devices models.

Large Signal Evaluation of Nonlinear HBT Model

The performance of recently developed Large Signal (LS) HBT model was evaluated with extensive LS measurements like Power spectrum, Load pull and Inter-modulation investigations. Proposed model has adopted temperature dependent leakage resistance and a simplified capacitance models. The model was implemented in ADS as SDD. Important feature of the model is that the main model parameters are taken directly from measurements in rather simple and understandable way. Results show good accuracy despite the simplicity of the model. To our knowledge the HBT model is one of a few HBT models which can handle high current & Power HBT devices, with significantly less model parameters with good accuracy.

Neuro-space mapping technique for semiconductor device modeling

This paper presents an application of the space mapping concept in the modeling of semiconductor devices. A recently proposed device modeling technique, called neuro-space mapping (Neuro-SM), is described to meet the constant need of new device models due to rapid progress in the semiconductor technology. Neuro-SM is a systematic method allowing us to exceed the present capabilities of the existing device models. It uses a neural network to map the voltage and current signals between an existing device model (coarse model) and the actual device behavior (fine model), such that the mapped model becomes an accurate representation of the new device. An efficient training method based on analytical sensitivity analysis for such mapping neural network is also addressed. The trained Neuro-SM model can retain the speed of the existing device model while improving the model accuracy. The benefit of the Neuro-SM method is demonstrated by examples of SiGe HBT and GaAs MESFET modeling and use of the models in harmonic balance simulation.

Effect of base–emitter breakdown on class-C power performance of common-base InGaP/GaAs HBTs

Under class-C common-base configuration, unit-finger InGaP/GaAs HBTs exhibit record power density of 15 mW/μm 2 emitter area. However, the power density decreases rapidly with increasing number of emitter fingers. Based on measured dynamic drive and load lines under nearly isothermal pulse operations, it was concluded that the power density of multi-finger HBTs is limited by base–emitter reverse breakdown. In addition, the base–emitter breakdown voltage is much lower under RF operation than under DC operation. The RF base–emitter breakdown effect was added to a commercially available large-signal HBT model, which more accurately predicted the class-C power performance of common-base multi-finger HBTs.

SiGe HBT large signal equivalent circuit model

A large signal equivalent circuit model for SiGe HBT is established based on the physical model of the transistor. The quasi saturation effect and the self-heating effect are taken into account in this equivalent circuit model. The model is composed of the intrinsic and the extrinsic parts, and has the features of clear physical meaning and simple topology. The model is embedded in the DEVEQ(Device Equations Developer) of PSPICE and simulated and analyzed by the PSPICE. The results conform to the theoretically analyzed conclusion and are in accordance with the published results in the literature.

Analysis and design of wide-band SiGe HBT active mixers

The frequency response of SiGe HBT active mixers based on the Gilbert cell topology is analyzed theoretically. The time-varying operation of the active mixer is taken into account by applying conversion matrix analysis. The main bandwidth-limiting mechanisms experienced in SiGe HBT active mixers performing frequency conversion of wide-band signals is discussed. The analysis is verified by computer simulations using a realistic high-frequency large-signal SiGe HBT model. An active mixer design based on the Gilbert cell topology modified for wide-band operation using emitter degenerated transconductance stage and shunt feedback load stage is discussed. Experimental results are given for an active mixer implemented in a 0.8-/spl mu/m 35-GHz f/sub T/ SiGe HBT BiCMOS process.