Superminiaturized Leadless Double-em-awed Mixer-modulator With Thick Film Print /fire Process

Abstract

A Supern in ia tu r i zed doublebalanced mixermodulator(D8H) by t h i c k f i lm techno logy has been developed,in which a couple o f phase transformers w i t h t h i c k f i l m conductor and d i e l e c t r i c m a t e r i a l s a r e connected t o a quad-diode chip.0ptimization o f the width o f a th ick f i l m coi1,the d ie lec t r i c constant and thickness o f d i e i e c t r i c layers between the c o i l s made DBMs t o work a t 0.9.1.5 and 1.9GHz band respect ively. 1 . In t roduc t ion As the s i z e r e d u c t i o n and accuracy o f movable communica t ion equ ipment ,such as a handy phone , i s improved,a vigorous e f f o r t i s being made t o min ia tu r ize e lec t ron i c components such as a double-balanced mixeraodulator(DBH1 with h igher accuracy t o be used i n t h e equipment. A conventional mixer-modulator has consisted o f a phase t rans former made o f a f e r r i t e core and t h e technique o f wire bonding, We have developed a leadless double-balanced mixersodulator(D8M) f o r Surface Mount Technology which i s realized by a piair o f phase transformers with multilayered co i l s o f th ick film. We investigated the optimal width and length of a prlnted/fired co i l and the th ickness/perai t iv i ty o f i n s u l a t e d l a y e r s between t h e c o i l s , t o c r e a t e a t r a n s f o r m e r w o r k i n g a t t h e f r e q u e n c y b a n d o f 0.9.1.5,or1.9GHlz. The size o f the DBW i s compact as 5.0 x 4.5 x Z.O(ma) and i t s conversion l oss i s 7 o r 8 dB and i n t e r c e p t point(1P) i s 8 o r 10 dB respec t i ve l y . 2.Method o f experiment 3-1. Basic conf igura t ion o f Phase transformer An equivalent c i r c u i t o f the DBH i s shown i n Figure 1 Thick film p r i n t / f i r e process i s used t o f o r i c o i l s f o r a phase transformer as shown i n the schematic o f Figure 2 F i r s t g o l d pas te i s p r i n t e d and fired(850.C) on t h e alumina(96X) substrate t o form the pa i r o f c o i l s o f 7-b and 6-d i n Figure 2-a, followed by p r in t i ng and fir ing(850' C) of d ie lec t r i c layer . The process i s repeated, i n order o f 1-8,4-5(Figure 2-b) and 2-a and J-c(Figure 2-c) t o cons t ruc t t he phase t rans former . f i g u r e 2-d shows a schematic cross sec t ion o f the p r i n t e d and f i r e d phase transformer. 'The F igure a l s o i nd i ca tes connections t o diodes. Each e lec t rode o f lead less quad-diode w i t h a forward voltage, Vf=O.ZV. i s wire-bonded t o complete the DBM. I n the exiierinent, we investigated (a) the width and length o f the conductor trace t o form a c o i l and (b) the th i ckness and p e r m i t i v i t y o f i n s u l a t i n g d i e l e c t r i c layer between c o i l s .