Showing papers by "Bumman Kim published in 1997"
TL;DR: In this paper, the authors investigated the cancellation effects of nonlinear elements and found that the output nonlinear current components generated by emitter-base current source and base collector current source cancel each other almost exactly, resulting in high linear characteristics of HBTs.
Abstract: The intermodulation (IM) mechanism of heterojunction bipolar transistors (HBTs) has been studied by using an analytical nonlinear equivalent circuit model and Volterra-series analysis of the model. Although the third-order IM intercept point (IP3) does not depend on the emitter parameter, it is appreciably affected by base and collector parameters and has been substantially improved by utilizing punchthrough collector structure. The measured IP3 of punchthrough collector HBTs is 31 dBm with 150-mW dc power, which is higher than that of normal collector HBTs by 3 dB. The investigation of the cancellation effects of nonlinear elements reveals that the output nonlinear current components generated by emitter-base current source and base-collector current source cancel each other almost exactly, resulting in high linear characteristics of HBTs.
45 citations
08 Sep 1997
TL;DR: In this article, a simple method of the higher order channel current in GaAs MESFET has been developed, where low frequency ( ~ 60 MHz ) two-tone signals are employed to measure the harmonic components.
Abstract: A simple new extraction method of the higher order channel current in GaAs MESFET has been developed. Low frequency ( ~ 60 MHz ) two-tone signals are employed to measure the harmonic components. The measured data are fitted to the Volterra series analysis for extracting of Taylor series coefficients of the nonlinear channel current. This proposed parameter extraction procedure is simple and straightforward. The extracted current model is utilized successfully for intermodulation analysis.
6 citations
TL;DR: In this paper, the authors showed that the use of an electrically abrupt emitter-base junction considerably reduces the 1/f noise of self-aligned AlGaAs/GaAs heterojunction bipolar transistor (HBT).
Abstract: It is shown that the use of an electrically abrupt emitter-base junction considerably reduces the 1/f noise of self-aligned AlGaAs/GaAs heterojunction bipolar transistor (HBT). Although this device does not have depleted AlGaAs ledge passivation layer, the low-frequency noise spectra show a very low 1/f noise corner frequency of less than 10 kHz, which is much lower than previously reported value of about 100 kHz from conventional passivated or unpassivated AlGaAs/GaAs HBT's. Except for a residual generation-recombination (g-r) noise component, the noise power is comparable to that of Si BJT. It is also found that the low-frequency noise power of the AlGaAs/GaAs HBT is proportional to the extrinsic GaAs base surface recombination current square. Unlike the other HBT's reported, the noise sources associated with interface state and emitter-base (E-B) space charge region recombination are not significant for our device.
5 citations
08 Sep 1997
TL;DR: In this paper, an accurate analytical expression for thermal capacitance (Cth) is derived, and a direct extraction scheme for the current source model parameter, without any trimming process, is proposed.
Abstract: A new equivalent circuit parameter extraction method for HBT is proposed. An accurate analytical expression for thermal capacitance (Cth) is derived. This equation shows the previous expression for Cth is deprived. This equation shows the previous expression for Cth is erroneous. And a direct extraction scheme for the current source model parameter, without any trimming process, is proposed. This scheme uses the Gummel-plot in which the thermal effect and voltage drop in parasitic resistance are removed.
3 citations
08 Jun 1997
TL;DR: In this article, the surface recombination and its 1/f noise properties of AlGaAs/GaAs HBTs were investigated as a function of the emitter-base structure and the surface passivation condition.
Abstract: We have investigated the surface recombination and its 1/f noise properties of AlGaAs/GaAs HBT's as a function of the emitter-base structure and the surface passivation condition. It is found that the surface recombination 1/f noise can be significantly reduced by the heterojunction launcher of the abrupt junction with 30% Al mole fraction emitter. The depleted AlGaAs ledge surface passivation further suppresses the surface recombination currents. Consequently, we have achieved a very low 1/f noise corner frequency of 2.8 kHz at the collector current density of 10 kA/cm/sup 2/. The dominant noise source of the HBT is not a surface recombination current, but a bulk current noise. This is the lowest 1/f noise corner frequency among the III-V compound semiconductor devices, and comparable to those of low-noise Si BJTs.
2 citations
02 Dec 1997
TL;DR: In this paper, a thermal design and fabricated X-band 0.5 W class power HBTs based on the thermal design was performed and they adopted an HBT with emitter-to-emitter spacing of 30 /spl mu/m as a standard device.
Abstract: We performed systematical thermal design and fabricated X-band 0.5 W class power HBTs. Based on the thermal design, we adopted an HBT with emitter-to-emitter spacing of 30 /spl mu/m as a standard device. The collector-emitter breakdown voltage is 16 V indicating that 8 V operation is possible. f/sub t/, f/sub max/ and output power of the HBT at 10 GHz are 67, 58 GHz and 0.58 W, respectively. Various kinds of HBTs with different structures have been studied for reducing the thermal effects and we will present the dominant effect on thermal problems and the measurement data for thermal design guide.
2 citations
TL;DR: An accurate Gummel plot model of HBT at a wide range of current level and temperatures has been established in this paper, which contains a bias and temperature-dependent parasitic resistance and temperature dependent temperature coefficient of base-emitter turn-on voltage.
Abstract: An accurate Gummel plot model of HBT at a wide range of current level and temperatures has been established. The model contains a bias- and temperature-dependent parasitic resistance and temperature-dependent temperature coefficient of base–emitter turn-on voltage. The average error between the measurement data and calculated results was below 4% at 300–450 K, indicating that this model is useful for the optimum thermal design of high-power HBTs. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 38–41, 1997.
2 citations