GaAs HBT Microwave Power Transistor with On-Chip Stabilization Network

An lnGaP/GaAs HBT microwave power transistor with on-chip parallel RC stabilization network is developed with a standard GaAs MMIC process. From the stability factor K, the device shows unconditional stability in a wide frequency range due to the RC network. The power characteristics of the device as measured by a loadpull system show that the large-signal performance of the power transistor is affected slightly by the RC network. Psat is 30dBm at 5.4GHz,and PldB is larger than 21.6dBm at llGHz. The stability of the device due to RC network is proved by a power combination circuit. This makes the power transistor very suitable for applications in microwavc high power ttBT amplifiers.

Low Voltage Class C SiGe Microwave Power HBTs

The structure and microwave characteristics of low-voltage SiGe power HBTs are given.With this structure,the device can operate in a low-voltage and high-current state.By using an interdigital emitter strip layout and the operating voltage ranging from 3 to 4V,the output power in Class C operation can reach 1 65W at 1GHz,with the gain of 8dB.The highest collector efficiency is 67 8% under 3V.

Analytical Model of Surface Field Distribution and Breakdown Voltage for RESURF LDMOS Transistor

An analytical model of the surface field distribution and breakdown voltage of the reduced surface field lateral double diffusion MOS transistor is proposed.Based on the 2-D Poisson's equation solution,the derived model gives the closed form solutions of the surface potential and electrical field distributions as a function of the structure parameters and drain bias.A criterion for obtaining the optimal trade-off between the breakdown voltage and on-resistance is also presented to serve to quantify the maximum breakdown voltage and optimal relations of all design parameters.Analytical results are shown in good agreement with the numerical analysis obtained by the semiconductor device simulator MEDICI and previous reported experimental data.

Design of a High Efficiency Boost DC-DC Converter

An accurate circuit of PWM/PFM mode converting and a circuit of auto-adaptively adjusting dimension of power transistor are described.The duty cycle of the signal when the control mode converts can be gained accurately by using ratios of currents and capacitances,and an optimal dimension of power transistor is derived with different loads.The converter is designed by 0.35μm standard CMOS technology.Simulation results indicate that the converter starts work at 0.8 V input voltage.Combined with synchronized rectification,the transfer efficiency is higher than 90%with full load range,and achieves 97.5%at rating output.

Storage life of power switching transistors based on performance degradation data

NPN-type small and medium power switching transistors in 3DK series are used to conduct analyses and studies of accelerating degradation. Through three group studies of accelerating degradation in different temperature-humidity constant stresses, the failure sensitive parameters of transistors are identified and the lifetime of samples is extrapolated from the performance degradation data. Average lifetimes in three common distributions are given, when, combined with the Hallberg-Peck temperature-humidity model, the storage lifetime of transistor samples in the natural storage condition is extrapolated between 105-10^7 h. According to its definition, the accelerating factor is 1462 in 100 ℃/100% relative humidity （RH） stress condition, and 25 ℃/25% RH stress con- dition. Finally, the degradation causes of performance parameters of the test samples are analyzed. The findings can provide certain references for the storage reliability of domestic transistors.

The Instability of Terahertz Plasma Waves in Two Dimensional Gated and Ungated Quantum Electron Gas

The instability of terahertz（THz）plasma waves in two-dimensional（2D）quantum electron gas in a nanometer field effect transistor（FET）with asymmetrical boundary conditions has been investigated.We analyze THz plasma waves of two parts of the 2D quantum electron gas：gated and ungated regions.The results show that the radiation frequency and the increment（radiation power）in 2D ungated quantum electron gas are much higher than that in 2D gated quantum electron gas.The quantum effects always enhance the radiation power and enlarge the region of instability in both cases.This allows us to conclude that 2D quantum electron gas in the transistor channel is important for the emission and detection process and both gated and ungated parts take part in that process.

The influence of RF power on the electrical properties of sputtered amorphous InGa-Zn-O thin films and devices

The influence of radio frequency（RF） power on the properties of magnetron sputtered amorphous indium gallium zinc oxide（a-IGZO） thin films and the related thin-film transistor（TFT） devices is investigated comprehensively.A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined.The results prove that the deposition rate sensitively depends on RF power.In addition,the carrier concentration increases from 0.91 x 1019 to 2.15 x 1019 cm-3 with the RF power rising from 40 to 80 W,which may account for the corresponding decrease in the resistivity of the a-IGZO thin films.No evident impacts of RF power are observed on the surface roughness,crystalline nature and stoichiometry of the a-IGZO samples.On the other hand,optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W,as is supposed to result from the carrierinduced band-filling effect.The rise in RF power can also affect the performance of a-IGZO TFTs,in particular by increasing the field-effect mobility clearly,which is assumed to be due to the alteration of the extended states in a-IGZO thin films.

Single-event burnout hardening of planar power MOSFET with partially widened trench source

We present a single-event burnout（SEB） hardened planar power MOSFET with partially widened trench sources by three-dimensional（3 D） numerical simulation. The advantage of the proposed structure is that the work of the parasitic bipolar transistor inherited in the power MOSFET is suppressed effectively due to the elimination of the most sensitive region（P-well region below the N＋ source）. The simulation result shows that the proposed structure can enhance the SEB survivability significantly. The critical value of linear energy transfer（LET）,which indicates the maximum deposited energy on the device without SEB behavior, increases from 0.06 to0.7 p C/μm. The SEB threshold voltage increases to 120 V, which is 80% of the rated breakdown voltage. Meanwhile, the main parameter characteristics of the proposed structure remain similar with those of the conventional planar structure. Therefore, this structure offers a potential optimization path to planar power MOSFET with high SEB survivability for space and atmospheric applications.

A novel electrical measurement method of peak junction temperature based on the excessive thermotaxis effect of low current

It has been a scientific and technological problem in the field of microelectronics for several decades that the electrical method is used to measure the peak junction temperature of power transistors. Based on the excessive thermotaxis effect of low current, a novel electrical measurement method of the peak junction temperature is presented in this paper. The method is called the thermal spectrum analysis method of transistors, simply designated TSA （thermal spectrum analysis method）. Unlike the common method which uses a single measuring current, TSA uses multi-step currents to measure temperature-sensitive parameters. Based on the excessive thermotaxis effect of low current and the sub-transistor parallel model, the peak junction temperature and non-uniform property of junction temperature distribution are analyzed successfully.