Microstrip to CPW transition

2004-30338

윤정훈

Advantage of MS & CPW Low cost, compact size, and easy integration for devices

demand Low-loss, wideband, and compact transition

Two main techniques for the transition by electrical contact

• usually call for Via holes, bonding wires, or abrupt steps in the conductor

• Compact size and wide bandwidth• Some degree of mechanical complexity

by electromagnetic coupling• No wired bonds or via holes• Narrow bandwidth and larger size Recently wider bandwidth transition

Electrical Contact (1)

Case 1 : ribbon Superposition of two different substrates

• upper one works in a microstrip mode

• lower one works in a coplanar mode

a small capacitance is added at the beginning of the coplanar line• lowpass filter

maximum cut-off frequency is related with the height h1

Gold ribbon

inductancecapacitance

Electrical Contact (2)

Case 2 : air bridge Microstrip to CPW on GaAs chip substrate

Case 3 : via hole Microstrip to CPW on opposite sides of a common substrate

Electromagnetric Coupling(1)

Case 1 : uniplanar this one uses the coupling between the ground plane of the mi

crostrip and the ground planes of the coplanar line• Analyzed as a bandpass filter

cutoff frequency is determined by the length of the coupling region

With radial coupling stub

Electromagnetric Coupling(2)

as n increases, S11 decreases

Gradual transformation Return loss

as the length of the transition increases,

Bandwidth increases as well

Case 2 : Surface to surface transition CPW on one substrate surface to a MS on another

Types • Single-substrate transition

on opposite sides of a single substrate gap size of roughly 10 % of the total length empirically give the

best results• Chip to motherboard transition

Electromagnetric Coupling(3)

Wire bonding • can seriously degrade circuit operation• Is very labor intensive

No wire bonding • Improve performance

• Reduce costgap

Electromagnetric Coupling(4)

Chip to motherboard transition

Ground plane of the chip is removed in the area over the coupling region

The chip and mother board ground planes coincide

Single substrate transition

widening broadband transmission behavior

A variety of transition structure

As Sc is enlargedEM coupling becomes tightRasining the equivalent series capacitivie coupling

Constitute a Broad Passband with two minimum values

(A)

s

Widening the width

Futher expanding the transmission passband

As Sc is enlarged,

Lower end of a passband is moved to low frequency

But higher end of a passband is unchanged

(B)

By the coupled-strip length d

As d is enlarged,

the wide passband gradually moves down

Electromagnetric Coupling(3)

Case 2 : radial stub Radial shape of the open stub & shorted arm allow wider band

width operation signal is effectively transferred through resonant coupling

microstrip Two short slot arms

Two radial open stub

Stub reactanceMutual cancellation

conclusion

여러구조의 microstrip-to-CPW transition. 각 transition 의 다지인 패러미터 . 용도에 맞는 transition 구조의 선택 및 디자인에 도움 .

Reference

[1] Lin, T.-H.; "Via-free broadband microstrip to CPW transition," Electronics Letters , Volume: 37 , Issue: 15 ,Pages:960 - 961, 19 Jul 2001

[2]Safwata, A.M.E.; Zaki, K.A.; Johnson, W.; Lee, C.H.;"Novel design for coplanar waveguide to microstrip transition," Microwave Symposium Digest, 2001 IEEE MTT-S International , Volume: 2 , 20-25, Pages:607 - 610 vol.2, May 2001

[3]Lei Zhu; Menzel, W.; "Broad-band microstrip-to-CPW transition via frequency-dependent electromagnetic coupling," Microwave Theory and Techniques, IEEE Transactions on , Volume: 52 , Issue: 5 , Pages:1517 – 1522, May 2004

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[5] Hang Jin; Vahldieck, R.; Jifu Huang; Russer, P.; "Rigorous analysis of mixed transmission line interconnects using the frequency-domain TLM method," Microwave Theory and Techniques, IEEE Transactions on , Volume: 41 , Issue: 12 , Pages:2248 - 2255, Dec. 1993

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[7] Gauthier, G.P.; Katehi, L.P.; Rebeiz, G.M.; "W-Band finite ground coplanar waveguide (FGGPW) to microstrip line transition," Microwave Symposium Digest, 1998 IEEE MTT-S International , Volume: 1 , 7-12 , Pages:107 - 109 vol.1, June 1998

[8] Guizhen Zheng; Papapolymerou, J.; Tentzeris, M.M.; "Wideband coplanar waveguide RF probe pad to microstrip transitions without via holes," Microwave and Wireless Components Letters, IEEE [see also IEEE Microwave and Guided Wave Letters] , Volume: 13 , Issue: 12 , Pages:544 - 546, Dec. 2003

[9] Chiu, T.;"A building-block design scheme for planar transmission-line transitions," Microwaves, Antennas and Propagation, IEE Proceedings - , Volume: 150 , Issue: 6 , Pages:405 - 410, Dec 2003

[10] Burke, J.J.; Jackson, R.W.; "Surface-to-surface transition via electromagnetic coupling of microstrip and coplanar waveguide," Microwave Theory and Techniques, IEEE Transactions on , Volume: 37 , Issue: 3 , Pages:519 - 525, March 1989