Dondee Navarro

HiSIM2: Advanced MOSFET Model Valid for RF Circuit Simulation

The compact MOSFET model development trend leads to models based on the channel surface potential, allowing higher accuracy and a reduced number of model parameters. Among these, the Hiroshima University Semiconductor Technology Academic Research Center IGFET Model (HiSIM) solves the surface potentials with an efficient physically correct iteration procedure, thus avoiding additional approximations without any computer run-time penalty. It is further demonstrated that excellent model accuracy for higher-order phenomena, which is a prerequisite for accurate RF circuit simulation, is achieved by HiSIM without any new model parameters in addition to those for describing the current-voltage characteristics

Completely Surface-Potential-Based Compact Model of the Fully Depleted SOI-MOSFET Including Short-Channel Effects

The reported circuit simulation model Hiroshima University semiconductor technology academic research center IGFET model silicon-on-insulator (HiSIM-SOI) for the fully depleted SOI-MOSFET is based on a complete surface-potential description. Not only the surface potential in the MOSFET channel, but also the potentials at both surfaces of the buried oxide are solved iteratively, which allows including of all relevant device features of the SOI-MOSFET explicitly and in a physically correct way. In particular, an additional parasitic electric field, induced by the surface-potential distribution at the buried oxide, has to be included for accurate modeling of the short-channel effects. The total iteration time for surface potential calculation with HiSIM-SOI is under most bias conditions only a factor 2.0 (up to a factor 3.0 for some bias conditions) longer than for the bulk-MOSFET HiSIM model, where just the channel surface potential is involved. It is verified that HiSIM-SOI reproduces measured current-voltage (I-V) and 1/f noise characteristics of a 250-nm fully depleted SOI technology in the complete operating range with an average error of 1% and 15%, respectively. Stable convergence of HiSIM-SOI in the circuit simulation is confirmed

A Carrier-Transit-Delay-Based Nonquasi-Static MOSFET Model for Circuit Simulation and Its Application to Harmonic Distortion Analysis

In this paper, a compact model of nonquasi-static (NQS) carrier-transport effects in MOSFETs is reported, which takes into account the carrier-response delay to form the channel. The NQS model, as implemented in the surface-potential-based MOSFET Hiroshima University STARC IGFET model, is verified to predict the correct transient terminal currents and to achieve a stable circuit simulation. Simulation results show that the NQS model can even reduce the circuit simulation time in some cases due to the elimination of unphysical overshoot peaks normally calculated by a QS-model. An average additional computational cost of only 3% is demonstrated for common test circuits. Furthermore, harmonic distortion characteristics are investigated using the developed NQS model. While the distortion characteristics at low drain bias and low switching frequency are determined mainly by carrier mobility, distortion characteristics at high frequency are found to be strongly influenced by channel charging/discharging

HiSIM-IGBT: A Compact Si-IGBT Model for Power Electronic Circuit Design

A physics-based compact model of insulated-gate bipolar transistors (IGBTs) for power electronic circuit simulation is presented. The compact model is constructed as a combination of a metal-oxide-semiconductor field-effect transistor (MOSFET) part and a bipolar junction transistor (BJT) part with a conductivity-modulated base resistance in between them and is named “HiSIM-IGBT.” The model considers the potential distribution from the MOSFET channel to the two BJT junctions explicitly by solving important internal node potentials self-consistently. The IGBT output current at the collector terminal is governed by the base resistance of the bipolar part and the MOSFET characteristics, which is confirmed to be described accurately. The model is verified to accurately reproduce measured transient behaviors of switching test circuits which are basic components of practically used power electronic circuits.

High frequency response of p-i-n photodiodes analyzed by an analytical model in Fourier space

A formulation of carrier transport in vertical p-i-n photodiodes is presented in Fourier space, taking into account diffusion effects of carriers outside the intrinsic region. High frequency response of photodiodes is investigated using the model. Calculated results show that diffusion limits the cutoff frequency characteristics of photodiodes with short intrinsic region length. Photocurrent calculations via the spectral method are in excellent agreement with two-dimensional device simulator results. The model can be utilized in circuit simulation because of its reduced computational runtime.

MOSFET harmonic distortion analysis up to the non-quasi-static frequency regime

MOSFET harmonic distortion characteristics up to the cutoff frequency (fT) are measured and analyzed with the MOSFET model HiSIM. While distortion characteristics at low frequency are determined by carrier mobility, characteristics at high frequency are influenced by the time delay of carriers to form the channel. At low frequency, IP3 values, calculated using a quasi-static model, correspond to values from the conventional method of extraction. For accurate prediction of IP3, non-quasi-static effects become necessary at high-frequency switching above fT/2

Modeling of Carrier Transport Dynamics at GHz-Frequencies for RF Circuit-Simulation

Carrier dynamics in a MOSFET channel under fast time-varying gate input is included in the modeling for circuit simulation and implemented in SPICE3f5 at only 7% increased computational runtime cost. Correct reproduction of transient drain currents as well as harmonic-distortion characteristics are verified. While the carrier dynamics under low-frequency operation is mostly governed by the carrier mobility in the channel, the dominant factor under high-frequency operation changes to channel charging and discharging.

Analysis and Compact Modeling of MOSFET High-Frequency Noise

We have developed a high-frequency noise model for short channel MOSFETs by considering the position dependent surface potential which results in a non-uniform mobility distribution along the channel. The chosen approach successfully reproduces the induced-gate noise and the cross-correlation noise between drain and gate for short channel MOSFETs without additional model parameters. In particular, the gate noise characteristics at GHz frequencies are accurately captured. The newly developed high-frequency noise model is implemented in the complete surface-potential based MOSFET model HiSIM (Hiroshima-university STARC IGFET Model) for circuit simulation

HiSIM2 Circuit simulation - Solving the speed versus accuracy crisis

The development trend in compact modeling goes toward surface-potential-based approaches and leads to models like HiSIM2, with higher accuracy, fewer model parameters, and shorter computer runtime than achievable with the conventional threshold-voltage-based approaches. The main motivation for continuing this development effort is to realize a sufficient design capability of RF circuits with advanced MOSFETs, where many higher-order phenomena affect the circuit performance, as well as of large mixed-signal circuits, where both accuracy and short simulation time are a must. The trend toward the surface potential brings compact modeling for circuit simulation also much closer to 2D and three-dimensional numerical device simulation. Therefore, both approaches can now come together and work united to achieve the common goal of realizing rapid technology progress for the benefit of the society

Shot noise modeling in metal-oxide-semiconductor field effect transistors under sub-threshold Condition

We have developed a new simulation methodology for predicting shot noise intensity in Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET). In our approach, shot noise in MOSFETs is calculated by employing a two dimensional device simulator in conjunction with the shot noise model of a p-n junction. The accuracy of the noise model has been demonstrated by comparing simulation results with measured noise data of p-n diodes. The intensity of shot noise in various n-MOSFET devices under various bias conditions was estimated beyond GHz operational frequency by using our simulation scheme. At DC or low-frequency region, sub-threshold current dominates the intensity of shot noise. Therefore, shot noise is independent on frequency in this region, and its intensity is exponentially depends on V G , proportional to L -1 , and almost independent on V D . At high-frequency region above GHz frequency, on the other hand, shot noise intensity depends on frequency and is much larger than that of low-frequency region. In particular, the intensity of the RF shot noise is almost independent on L, V D and V G . This suggests that high-frequency shot noise intensity of MOSFETs is decided only by the conditions of source-bulk junction.