Liming Gu

Dual-gate GaN-HEMT SPDT switch with high isolation

In this work, an analytical approach to the design of high isolation dual-gate GaN-HEMT single-pole double-throw (SPDT) switches is presented. An R-C-R circuit is used as a band-rejection filter at the specified frequency in the OFF-state in order to realize the high isolation performance. Simulated performance of a complete SPDT using the proposed approach is presented. From DC to 3 GHz, the simulated isolation is 10 dB higher than the case without R-C-R circuit type, demonstrating the approach feasibility and effectiveness.

Dual-band GaN power amplifiers with novel DC biasing networks incorporating offset DSPSL

This paper presents a novel dual-band DC biasing network and its application in the design of GaN power amplifiers (PA). By integrating offset double sided parallel strip line (DSPSL) which can easily realize high characteristic impedance and thus narrow microstrip line, the proposed biasing network can obtain much higher operation frequency ratio than the conventional design. To demonstrate the new methodology, two dual-band GaN power amplifiers applying the presented dual-band DC biasing network are implemented. The operation frequencies are 1.8/3.5 GHz and 0.9/3.5 GHz. Three-section networks for complex load are used for dual-frequency input and output matching. Simulation and measurement shows good agreement, which fully validate the feasibility and validity of the presented DC bias networks in power amplifier designs.

Investigations on bonding wire array for interconnect of RFICs

In this paper, analytical Moment Method (MoM) is used as one method for analyzing the equivalence between a flat solid rectangular plate and an array of bond wires. In addition, fuzzy Electromagnetism (EM) method is firstly used to derive the formulas of the inductance and capacitance of bonding wire array. To verify the validity and accuracy of proposed formulas for the bonding wire array, several structures with different numbers of bonding wires have been analyzed and simulated. Very good agreements can be found between the simulated S-parameters from the structures and that of the corresponding equivalent circuits. The proposed formulas can be used effectively in the design of practical bonding wire array in internal matching of transistors and IC packaging etc.

Tri-band microstrip bandpass filter using input/output cross coupling

A compact tri-band bandpass filter using input/output cross coupling is proposed. Three passbands can be adjusted by changing the characteristic impedance of the T-shaped structure with a shorted stub. The three passbands are designed to operate at 1.85, 3.5 and 5.2 GHz based on the T-shaped structure. Four transmission zeros are used to realise high selectivity for the passbands. Good agreement can be observed between the measured and simulated results.