Yan-Ting Lin

SiGe HBT Large-Signal Table-Based Model With the Avalanche Breakdown Effect Considered

In this paper, a table-based large-signal model for silicon germanium heterojunction bipolar transistors with the introduction of a breakdown network is presented to describe the avalanche breakdown effect of the base-collector junction on direct current and RF characteristics completely. Input oscillation and output inductive behaviors in the breakdown regime are found to be due to impact ionization induced holes and electrons, respectively. The avalanche breakdown effect and early effect modeled by the breakdown network and output resistance, respectively, can be distinguished in the presented model. In addition, a good agreement between the extracted total input and output resistances at RF and dc is obtained. The validity of this presented large-signal table-based model with multibias intrinsic parameters has been verified through the measured output spectrum and waveform.

Investigation of Linearity in the High Electric Field Region for SiGe HBTs Based on Volterra Series

In this paper, avalanche breakdown operation has been demonstrated to have a positive impact on RF linearity performance for silicon germanium (SiGe) heterojunction bipolar transistors (HBTs) due to a nonlinear cancellation mechanism between a breakdown inductance and a base-collector capacitance according to the presented Volterra analysis results. As nonlinearity of breakdown inductance increases, linearity can be improved due to its contribution to nonlinear cancellation when variation of an avalanche multiplication factor (M-1) enlarges. In addition to collector current dependence on M-1, collector-base voltage dependence on M-1 is further taken into account to investigate linearity of SiGe HBTs. Linearity at breakdown can be characterized and presented here in a region no matter whether a multiplication factor increases or decreases. The presented analysis results can be beneficial to the reliability investigation for SiGe HBT linearity in the breakdown region.

An Improved Cascade-Based Noise Deembedding Method for On-Wafer Noise Parameter Measurements

In this letter, a noise deembedding method is presented to improve accuracy of on-wafer noise measurements of metal-oxide-semiconductor field-effect transistors. This method further removes parasitic effects of the forward coupling and the dangling leg with transverse magnetic mode considered, which is different from the transverse electromagnetic mode of input/output interconnects. Compared with the conventional scalable noise deembedding methods, this modified method can remove these parasitic noise effects and then make the intrinsic parameters of a device more accurate for noise characterization. The presented method demonstrates better deembedded noise performance especially for 10.4% reduction of deembedded minimum noise figure from 1 to 18 GHz.

An improved large-signal model by artificial neural network for the MOSFETs operating in the breakdown region

Abstract An improved large-signal breakdown model establishment applying an artificial neural network (ANN) approach is presented for metal-oxide-semiconductor field-effect transistors (MOSFETs) operating in the breakdown regime for the first time. A neural network program with the feed-forward back propagation algorithm and Levenberg Marquardt optimization is utilized to obtain the MOSFET large-signal model for breakdown operation. When compared with the conventional model without the breakdown effects considered, more accurate large-signal characteristics in the breakdown regime can be obtained by incorporating the avalanche network using the ANN approach. The breakdown network is demonstrated to be significant for large-signal characterization at high bias according to the analysis of minimum acceptable error. Besides, the divergence problem due to the neglected avalanche network can be avoided during ANN training in the avalanche regime. The accuracy of the presented model can keep about 2% error. The presented ANN approach can be applied to device large-signal modeling in the impact ionization regime.

A simple and fast de-embedding procedure of X-parameter measurement for RF transistor characterization in the large-signal operating region

In this paper, a simple and fast de-embedding procedure suitable for the X-parameter measurement is presented. The X-parameters of the dummy structures including open and short are measured and then directly subtracted from the device under test (DUT) to remove parasitic effects. Compared with the conventional procedure, this approach can provide a fast and simple algorithm based on the matrix transformation to implement DUT de-embedding for the X-parameter measurement. The presented X-parameter de-embedding procedure can be applied to radio-frequency (RF) transistor characterization in the large-signal operating region.

An Improved Four-Port Equivalent Circuit Model of RF MOSFETs for Breakdown Operation

In this paper, an improved four-port radio-frequency (RF) model for metal-oxide-semiconductor field-effect transistors is extended to investigate the various RF breakdown phenomena where reliability is a concern for the first time. Reduction of isolation from drain to source as well as inductive behavior occurred at the drain, and source terminals in the breakdown region are analyzed and explained by using this modified four-port RF model incorporating with an inductive breakdown network. In addition, reduction of inductive source impedance in the breakdown regime is analyzed based on a series feedback mechanism and degradation of transconductance. Parameters of the modified four-port breakdown model are extracted by fitting measured four-port measurement data in the breakdown regime. Good agreement between measured and simulated 16 four-port scattering parameters (S-parameters) is achieved in the breakdown and saturation regions, validating the improved four-port breakdown model. Therefore, this model can be beneficial to RF amplifier designs in the breakdown regime with reliability considered.

Gate Length Dependence of Large-Signal Output Characteristics for the MOSFETs in the Breakdown Region Using X-Parameter Model

In this letter, the gate length dependence of X₂₁₂₁^S and X₂₁₂₁^T intercept behaviors for the MOSFETs in the breakdown region is first analyzed using the X-parameter model. Shorter gate length decreases X₂₁₂₁^S coefficients and increases X₂₁₂₁^T coefficients at high drain voltage and high input power due to the significant RF avalanche effect in the high field region. X₂₁₂₁^S and X₂₁₂₁^T coefficients are determined using artificial neural network. Good agreement between the measured and fitted output scattering wave is achieved. The presented analysis for the gate length dependence X₂₁₂₁^S and X₂₁₂₁^T can be beneficial to CMOS power amplifier designs with the scaled-down MOSFETs.

A New Method to Determine Avalanche Multiplication Factor Using Vector Network Analyzer for p-n Junctions

In this letter, a new and simple radio-frequency (RF) -based method with dead-space-based theory considered for mixed avalanche and tunneling mechanisms is presented to determine the pure avalanche multiplication factor up to near 1 MV/cm for the first time. By extracting the equivalent circuit parameters based on a vector network analyzer, the avalanche multiplication factor can be determined and can be distinguished from the tunneling multiplication factor. The saturated avalanche multiplication factor with increased electric field is observed at high field. This saturated phenomenon obtained from experimental data is the first reported result for the two-terminal p-n junction. The validity of the obtained avalanche multiplication factor is verified by the dead-space-based theory. The proposed alternative avalanche multiplication factor extraction can be applied to breakdown characterization for the state-of-the-art device such as impact-ionization metal-oxide semiconductor (I-MOS) transistor and tunnel devices.

Radio Frequency Current-Voltage Curve Including Breakdown Effect Implemented in Large Signal Model for Validation

A metal-oxide-semiconductor field-effect transistor (MOSFET) radio frequency current-voltage (RF I-V) curve with the drain breakdown effect considered is demonstrated for the first time. The validity of the presented approach is extended to the breakdown region by including the breakdown conductance when realizing the RF I-V curve. The presented RF I-V is verified by implementing this curve into a large signal model, and then the simulated output spectrum can agree well with the measured results. Therefore, this accurate breakdown RF I-V can provide a guideline for output performance analysis and RF circuit design.

A novel low-power transceiver topology for noncontact vital sign detection including the power management technique

In this paper, power management technique utilized in the direct down-conversion non-quadrature transceiver is presented for the low-power application of vital sign detection. The simultaneous switching noise (SSN) and overshoot and undershoot of the transient waveform distortion resulting from a pulse signal will give rise to interference with a vital sign signal. The pulse width, rise/fall time, and period of pulse bias are analyzed to mitigate the interference in this investigation. Significant issues about direct-current (DC) offset and noise confronted by the presented technique are addressed based on mathematical analysis. In radio-frequency (RF) transceiver architecture including power amplifier (PA), low-noise amplifier (LNA), and mixer, the current-reused (CRU) topology is utilized to achieve low DC power consumption. The post-layout simulation results exhibit that power consumption of the transceiver using the optimized pulse bias is reduced to 40% of the power consumption for transceiver applying the DC bias. In addition, DC offset and null detection point can be alleviated by tunable phase shifter. Display Omitted Power management technique is presented in the vital sign detection system.The interference with the vital sign signal due to pulse bias has been mitigated.The presented method reduces to 40% of the power consumption for the system using DC bias.