Sheng-Chun Wang

Characterization and modeling of SOI varactors at various temperatures

Capacitance and quality factor of accumulation-mode and inversion-mode MOS varactors in silicon-on-insulator CMOS process were measured over a temperature range of 0/spl deg/C/spl les/T/spl les/150/spl deg/C. The temperature coefficient of capacitance of inversion-mode devices is larger than that of accumulation-mode devices in the normal operating range, because the threshold voltage is sensitive to temperature. Besides, the quality factor decreases with increasing temperature for these two types of varactors due to the increase of parasitic resistance. A device model based on BSIM3v3 model is proposed to simulate the temperature effect. The modeling results of capacitance, series resistance and quality factor for SOI varactors have excellent agreement with measured results.

Comprehensive Noise Characterization and Modeling for 65-nm MOSFETs for Millimeter-Wave Applications

Using an external tuner-based method, this paper demonstrates a complete millimeter-wave noise characterization and modeling up to 60 GHz for 65-nm MOSFETs for the first time. Due to channel length modulation, the channel noise continues to increase and remains the most important noise source in the millimeter-wave band. Our experimental results further show that, with the downscaling of channel length, the gate resistance has more serious impact on the high-frequency noise parameters than the substrate resistance even in the millimeter-wave frequency.

On the RF Extrinsic Resistance Extraction for Partially-Depleted SOI MOSFETs

We have investigated the radio frequency (RF) extrinsic resistance extraction for partially-depleted (PD) silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistors (MOSFETs). Although the thick buried oxide in SOI devices can block the substrate coupling, the SOI neutral-body coupling effect is significant for RF applications. An equivalent circuit considering this effect has been proposed. Based on this equivalent circuit, a new model capturing the frequency dependence of extrinsic resistances has been derived. After considering the impact of quasi-neutral body, we have developed a physically accurate RF extrinsic resistance extraction methodology for PD SOI MOSFETs

RF Small-Signal and Noise Modeling for SOI Dynamic Threshold Voltage MOSFETs

Phone: +886-3-5726100 Fax: +886-3-5733795 E-mail: scwang@ndl.org.tw Department of Electronics Engineering, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu, Taiwan, R.O.C. 2 National Nano Device Laboratories, No. 26, Prosperity Rd. 1, Science-Based Industrial Park, Hsinchu, Taiwan, R.O.C. United Microelectronics Corporation, No. 3, Li-Hisn Rd. 2, Science-Based Industrial Park, Hsinchu, Taiwan, R.O.C.

Radio-Frequency Silicon-on-Insulator Modeling Considering the Neutral-Body Effect

This paper presents small-signal modeling for state-of-the-art radio-frequency (RF) silicon-on-insulator (SOI) metal–oxide–semiconductor field effect transistors (MOSFETs). Especially, we have incorporated the neutral-body effect in our RF SOI model. This effect is significant in both RF extrinsic and intrinsic modeling stages. In addition, we have developed a physically-accurate parameter extraction method based on our analytical expressions. Our modeling results agree well with the measured data and can capture the frequency dependences of both output conductance and capacitance in the GHz frequency region. The anomalous S22 and S21 behaviors as well as the output conductance rising effect observed in our measurements can be predicted and described using the proposed model.

Investigation of Temperature-Dependent High-Frequency Noise Characteristics for Deep-Submicrometer Bulk and SOI MOSFETs

The temperature dependence of high-frequency noise characteristics for deep-submicrometer bulk and silicon-on-insulator (SOI) MOSFETs has been experimentally examined in this paper. With the downscaling of the channel length, our paper indicates that the power spectral density of the channel noise (Sid) of the bulk MOSFET becomes less sensitive to temperature due to the smaller degradation of the channel conductance at zero drain bias gd0 as temperature rises. We also show that the SOI-specific floating-body and self-heating effects would result in higher white-noise gamma factor. Finally, for both the bulk and SOI MOSFETs, since transconductance gm significantly decreases as temperature increases, their minimum noise figure NFmin and equivalent noise resistance Rn would degrade with increasing temperature.

RF Extrinsic Resistance Extraction Considering Neutral-Body Effect for Partially-Depleted SOI MOSFETs

The extraction of extrinsic resistances is essential to RF CMOS modeling. In this work, we investigate the extrinsic resistance extraction for PD SOI MOSFETs. We have shown that, for RF SOI MOSFETs, the coupling path between the source and drain terminals through the neutral-body region beneath the gate-oxide layer makes the resistance expressions behave frequency-dependently. After taking this effect into account, we develop a physical RF extrinsic resistance extraction methodology for PD SOI MOSFETs

Investigation of High-Frequency Noise Characteristics in Tensile-Strained nMOSFETs

For the first time, the high-frequency noise behavior of tensile-strained n-channel metal-oxide-semiconductor field effect transistors, including their temperature dependency, is experimentally examined. Our experimental results show that with similar saturation voltages, the strained device is found to have larger channel noise than the control device at the same bias point. For given direct-current power consumption, however, due to enhanced transconductance, the strained device has better small signal behaviors (higher ft and fmax) and noise characteristics (smaller NFmin and Rn) than the control device.

Temperature-Dependent RF Small-Signal and Noise Characteristics of SOI Dynamic Threshold Voltage MOSFETs

In this paper, temperature-dependent RF small-signal and noise characteristics of silicon-on-insulator (SOI) dynamic threshold voltage (DT) MOSFETs are experimentally examined. In the low-voltage regime, both the cutoff and maximum oscillation frequencies (ft and fmax) tend to increase with temperature. In addition, the inherent body-related parasitics and the series resistance have much more impact on fmax than ft. Besides, we found that the noise stemmed from the body resistance (Rb) would contribute to the output noise current, and degrade the minimum noise figure (NFmin). Our study may provide insights for RF circuit design using advanced SOI DT MOSFETs.

Radio-Frequency Small-Signal and Noise Modeling for Silicon-on-Insulator Dynamic Threshold Voltage Metal–Oxide–Semiconductor Field-Effect Transistors

This paper presents small-signal and noise modeling for radio-frequency (RF) silicon-on-insulator (SOI) dynamic threshold voltage (DT) metal–oxide–semiconductor field-effect transistors (MOSFETs). The inherent body parasitics, such as source- and drain-side junction capacitances, and access body resistance have been incorporated in this model. In addition, the analytical equations useful for parameter extractions are derived. The modeling results show good agreements with the measured data both in RF small-signal and noise aspects up to 12 GHz. Besides, we have made comparisons of important model parameters for DT and standard MOSFETs. The extracted parameters show reasonable trend with respect to applying voltages and channel lengths, which reveals the accuracy of the extraction results using our proposed method.