Yukinobu Tarui

A 6-18 GHz 5-Bit Phase Shifter MMIC Using Series/Parallel LC Circuit

A high performance 6-18 GHz 5-bit reflection type phase shifter MMIC is presented. It employs a novel ultra-broad-band circuit design technique utilizing a series/parallel LC circuit for an 180° phase shift over all frequencies. The fabricated phase shifter MMIC with SPDT switch suitable for T/R modules has demonstrated a typical insertion loss of 9.4 dB+/¿1.4 dB, a maximum RMS amplitude error of 0.33 dB and a maximum RMS phase error of 7° over entire operating bandwidths.

A METHOD FOR DIVIDING RATIO EQUALIZATION OF POWER DIVIDING/COMBINING CIRCUITS USED IN A POWER AMPLIFIER

Most power amplifiers with several FETs in parallel utilize a two-way power dividing/combining circuit of asymmetric structure. The asymmetric structure provides unequal power dividing/combining characteristics. In this paper the power dividing/combining ratio as a function of the structure is calculated by using the method of moments and is verified by experiments. The relation between unequal power dividing/combining characteristics and the equal phase plane of current flow is also shown. Finally, a method of equalizing the power dividing/combining ratio by making branch line impedances unequal is presented.

X band low-cost GaN TR module with anti-radiation structure

Today AESA antenna is becoming more popular in various systems and for further use of it, lowering cost of key component like TR module is crucial. In this paper, a design of a low cost X band GaN module is described. In this module, all devices including HPA are surface mounted on resin board with highly enforced heat dissipation method inside resin. Furthermore unique anti-radiation property with EM shielded devices, enabling coverless module is adapted. The prototype module exhibits 13.3W output power with 30.8% efficiency at X band. Operational Isolation between channels is 29dB with coverless configuration. It weighs only 8.5g per channel, and its manufacturing cost is estimated to be 40% of our conventional GaAs module.

A Broadband Traveling-Wave Power Divider/Combiner using Asymmetric Tapered-Line Power Dividers

A compact and broadband traveling-wave power divider/combiner cascading 1:1:2 three-way and 1:1 two-way power dividers is presented. Both tapered-line power dividers have several strip resistors to obtain sufficient output isolations. Additional open stubs applied to the 1:1:2 three-way tapered-line power divider compensate phase velocity difference between asymmetrically coupled tapered lines. The fabricated four-way power divider/combiner shows broadband performances which are a 0.4-dB insertion loss and a 14-dB return loss at all ports over a 3:1 bandwidth in the C-Ku bands.

Calculation of loop oscillations of microwave high‐power amplifiers with several closed loop circuits and split‐cell matching methods for high stability

This paper presents calculated and measured results on the loop oscillations of high-power amplifiers with several closed loop circuits using multiple FET cells, showing that the frequency of loop oscillations depends on each closed loop circuit. It is also shown in calculation and verified by experiment that the oscillation due to the imbalance of FET cells can be removed by split-cell matching methods.