Yong Zhong Xiong

Particle swarm optimization and finite-element based approach for microwave filter design

A novel approach is proposed for compact planar microwave filter design. The powerful particle swarm optimization (PSO) and finite-element method (FEM) are combined together to allow optimal filter design with arbitrary geometries. This approach is much more flexible than traditional ones. An example using this PSO-FEM approach shows that this approach is effective to make the structure variation converge to the desired target and the final optimal filter structure has much smaller size.

Demonstration of aluminum-free metamorphic InP/In/sub 0.53/Ga/sub 0.47/As/InP double heterojunction bipolar transistors on GaAs substrates

We report, for the first time, the successful fabrication of aluminum-free metamorphic (MM) InP/In/sub 0.53/ Ga/sub 0.47/ As/InP double heterojunction bipolar transistors (DHBTs) on GaAs substrates with a linearly graded In/sub x/Ga/sub 1-x/P buffer grown by solid-source molecular beam epitaxy (SSMBE). Devices with 5/spl times/5 /spl mu/m/sup 2/ emitters display a peak current gain of 40 and a common-emitter breakdown voltage (BV/sub CE0/) higher than 9 V, a current gain cut-off frequency (f/sub T/) of 48 GHz and a maximum oscillation frequency (f/sub max/) of 42 GHz. A minimum noise figure of 2.9 dB and associated gain of 19.5 dB were measured at a collector current level of 2.6 mA at 2 GHz. Detailed analysis suggests that the degradation of the base-emitter heterojunction interface and the increase of bulk recombination are the most probable causes for the poorer device performance of current metamorphic HBTs compared with lattice-matched HBTs.

DC and microwave noise transient behavior of InP/InGaAs double heterojunction bipolar transistor (DHBT) with polyimide passivation

DC and microwave noise transient behavior of InP/InGaAs double heterojunction bipolar transistor (DHBT) with polyimide passivation is reported in this paper for the first time. The base transient current is believed to be due to the change of surface potential near the base-emitter junction perimeter at the polyimide/emitter interface resulting from a decrease in the amount of trapped electrons in the polyimide. We also find that the surface potential on the sidewall of collector-emitter affected by the charge trapping and detrapping in polyimide may induce a parasitic polyimide field effect transistor along the surface of the base-collector junction which results in an excess collector transient current. These base and collector current transients result in associated transient of broadband shot noise. The time dependence of microwave noise figures due to the excess transients is also investigated. The better understanding of the mechanisms of the noise transient behavior of the InP HBT device is very useful to improve the device and circuit reliability.

Scaling of microwave noise and small-signal parameters of InP/InGaAs DHBT with high DC current gain

The scaling of noise and small-signal parameters of InP double heterojunction bipolar transistors (DHBTs) with high DC gain are presented for the first time in this brief. As InP DHBTs have very low surface recombination and high DC current gain, the large size device can be viewed as consisting of n identical subcells. Using this approach, a set of equations was derived, which relate the noise and small-signal parameters between the large-size device and the subcells for scaling purposes. The experimental and theoretical results show that at the same collector current density and collector-emitter voltage, good scaling of the noise and small-signal parameters can be achieved between the large-size device and the subcells. Because of the nonscalable external base-collector capacitor (C/sub bc/), the effects of C/sub bc/ on the noise and small-signal parameters are also investigated. The large base-collector capacitance acts as a negative feedback providing the lower minimum noise figure value and higher value of the imaginary part of the optimum source admittance. The good agreement between the measured and the calculated results supports the scaling approach developed in this work for InP DHBTs that may be useful for the design of high frequency circuits using InP-based HBTs.

A compact bandpass filter using folded /spl lambda//4 coupled-line resonators

This paper presents a compact bandpass filter using folded /spl lambda//4 coupled-line resonators. Accurate model of this resonator and equations for extraction of the equivalent parallel-coupled-line structure representing the folded-line section are developed. A simple systematic design procedure is established for filter designers. Finally, a 3-pole bandpass filter with the new resonators is designed. The new folded-coupled-line filter exhibits a significant reduction in footprint compared to the conventional design.

Microwave noise and power performance of metamorphic InP heterojunction bipolar transistors

For the first time, microwave noise and power performance of metamorphic InP HBTs (MM-HBTs) grown on GaAs substrates are reported. We find that microwave performance of MM-HBTs are comparable to that of lattice-matched InP HBTs (LM-HBTs) of identical design but fabricated on an InP substrate. The preliminary results imply that the superior performance of InP HBTs can be confidently exploited with the more mature manufacturing technology of GaAs.

Direct extraction of equivalent circuit parameters for balun on silicon substrate

A direct extraction technique of equivalent circuit parameters for three-port balun on silicon substrate is developed. The extraction is based on two-port measurement instead of three-port by grounding the third port. This technique greatly simplified the measurement and extraction process. The extracted results are in excellent agreement with the measured results up to 10 GHz.

DC and microwave characteristics of metamorphic InP/In/sub 0.53/Ga/sub 0.47/As heterojunction bipolar transistors grown on GaAs substrates

We report, for the first time, a metamorphic InP/In/sub 0.53/Ga/sub 0.47/As/InP double heterojunction bipolar transistors (DHBTs) on GaAs substrates grown by Solid-Source molecular beam epitaxy (SSMBE). Detailed dc and microwave characterization were done on the fabricated self-aligned metamorphic DHBTs. Devices with 5/spl times/5 /spl mu/m/sup 2/ emitter area showed a typical peak current gain of 40, a common-emitter breakdown voltage (BV/sub CEO/) higher than 9 V, a current gain cut-off frequency (f/sub T/) of 46 GHz and a maximum oscillation frequency (f/sub MAX/) of 40 GHz. Detailed analysis suggests that the degradation of the base-emitter heterojunction interface and the increase of bulk recombination are the most probable causes for the poorer device performance of the current metamorphic HBTs compared to the lattice-matched HBTs.

A fast noise and Z-parameter transformations between common emitter and common base InP DHBT

A new approach has been developed that uses only a simple set of formulas to transform noise and Z-parameters between common emitter and common base configurations. This technique is based on the typical T-model of InP double-heterojunction bipolar transistor and calculated results agree with the experimental results, demonstrating that this approach is useful for many broad-band low-noise communication circuit designs.

Measurement and Simulation of Microwave Noise Transient of InP/InGaAs DHBT with Polyimide Passivattion

Measurement and simulation of microwave noise transient of InP/InGaAs DHBT with polyimide passivation is reported in this paper for the first time and is believed to contribute to the overall broadband shot noise. This work provides a better insight into the noise transient mechanism of InP HBTs due to polyimide passivation and can be used to improve the device and circuit reliability.