Yongheng Shang

Temporal Coupled-Mode Theory and the Combined Effect of Dual Orthogonal Resonant Modes in Microstrip Bandpass Filters

We propose a temporal coupled-mode theory for the design of microstrip bandpass filters with multi-resonant modes and reveals the mechanism of the filters based on multi-coupling and energy conservation theorem. As an example, the combined effect of the two orthogonal modes in dual-mode filters is analyzed in detail. By simply tuning the coupling efficiencies of the two resonant modes, two K-band integrated microstrip bandpass filters have been designed and demonstrate opposite asymmetric transmission responses. Both simulation and experiment results agree well with the theoretical analysis, which provides a new approach for filter design and optimization.

High-efficiency K-band MMIC power amplifier using multi-harmonic load terminations

In this paper, a high-efficiency K-band MMIC power amplifier using multi-harmonic load terminations is designed and implemented in a 0.15µm GaAs PHEMT processing technology. At the bias voltages of VD=5V and VG=-0.9V, the three-stage MMIC amplifier attains 25dB linear gain in average, 20dBm saturation power, lower than -15dB input return loss, and lower than -10dB output return loss from 25 to 27GHz. With this 2GHz bandwidth, the proposed amplifier can provide 40% higher power added efficiency than that of the conventional designs.

Design and Simulation of a Ku-band MMIC Power Amplifier

A compact 6 W AlGaAs/InGaAs/GaAs monolithic microwave integrated circuit (MMIC) high power amplifier (HPA) is proposed for Ku-band applications. This three-stage amplifier with layout size of 14.35 mm2 (4.39 mm×3.27 mm) is designed to fully match 50 O input and output impedance. with 8 V and 3300 mA DC bias condition, the MMIC delivers 30.4 dB small-signal gain, 37.8 dBm saturated output power with 23.4 % power added efficiency from 12 to 15 GHz. the 38.5 dBm of maximum output power with 27 % of peak power added efficiency at 13.3 GHz can be achieved. the amplifier circuit is fabricated in 0.25 μm pseudomorphic high electronic mobility transistor (pHEMT) technology.

A new meshing criterion for the equivalent thermal analysis of GaAs PHEMT MMICs

Abstract In this paper, a new meshing criterion for the equivalent thermal analysis of GaAs PHEMT MMICs (Monolithic microwave integrated circuit) is proposed. Based on the meshing criterion, an equivalent thermal model of GaAs PHEMTs with remarkably reduced mesh complexity is established, and the simplification of both layout pattern and vias of MMICs are performed. Theoretical analysis is applied for the calibration of the equivalent thermal model. Assisted by the meshing criterion, chip-level simulators are capable to obtain the peak temperature of MMICs without using averaging approximations, and achieve considerably high simulation accuracy. As examples, two MMIC power amplifiers are designed and implemented using GaAs PHEMT process. Thermal simulation and measurement results obtained with ANSYS ICEPAK and infrared thermography, respectively, show high consistency. The proposed meshing criterion can be applied to improve the accuracy of thermal analysis of MMICs, and the obtained precise peak temperature can be used to effectively assess the power threshold of the designed amplifiers in reliability tests.

A New Digital to Analog Converter Based on Low-Offset Bandgap Reference

This paper presents a new 12-bit digital to analog converter (DAC) circuit based on a low-offset bandgap reference (BGR) circuit with two cascade transistor structure and two self-contained feedback low-offset operational amplifiers to reduce the effects of offset operational amplifier voltage effect on the reference voltage, PMOS current-mirror mismatch, and its channel modulation. A Start-Up circuit with self-bias current architecture and multipoint voltage monitoring is employed to keep the BGR circuit working properly. Finally, a dual-resistor ladder DAC-Core circuit is used to generate an accuracy DAC output signal to the buffer operational amplifier. The proposed circuit was fabricated in CSMC 0.5źźm 5źV 1P4M process. The measured differential nonlinearity (DNL) of the output voltages is less than 0.45 LSB and integral nonlinearity (INL) less than 1.5 LSB at room temperature, consuming only 3.5źmW from a 5źV supply voltage. The DNL and INL at ź55°C and 125°C are presented as well together with the discussion of possibility of improving the DNL and INL accuracy in future design.

The Design and Life Test of a Multifunction Power Amplifier for Space Application

A new multifunction power amplifier (MFPA) is designed and fabricated for the application of point-to-point K-Band backhaul TR module. A DC temperature life test was performed to model the up-limit temperature effect of the designed MFPA under space application. After 240 hours of 100°C life test, the test results illustrate that the designed MFPA has only slight power degradation at the saturation region without change of the linear gain. The general performance of the designed MFPA satisfies the requirement of the application scenario.

The Design and Thermal Reliability Analysis of a High-Efficiency K-Band MMIC Medium-Power Amplifier with Multiharmonic Matching

A new high-efficiency K-band MMIC medium-power amplifier (PA) is designed with multiharmonic matching using GaAs pHEMT process technology. It has an operation frequency centered at 26 GHz with a bandwidth of 2 GHz. A 20 dBm 1 dB-compression-point output power and 40% efficiency are achieved. A novel thermal reliability analysis method based on ICEPAK is proposed also to evaluate its thermal characteristic. The test result by using a QFI InfraScope™ infrared imaging system is compared with the simulation result. It agrees well with an accuracy within ±1°C differences, which reflects the advantages of the thermal analysis method with respect to accuracy and convenience for use.