Power divider ( Arbitrary Termination Impedance, Arbitrary Power Division )

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Power divider ( Arbitrary Termination Impedance, Arbitrary Power Division ). 2004-21566 유지호. Contents. Necessity of the power divider Problems of conventional power dividers Size reduction technique Arbitrary termination Impedance technique Arbitrary power division technique

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Presentation Transcript

Power divider

( Arbitrary Termination Impedance,

Arbitrary Power Division )

2004-21566

유지호

Contents

• Necessity of the power divider
• Problems of conventional power dividers
• Size reduction technique
• Arbitrary termination Impedance technique
• Arbitrary power division technique
• Conclusion

Necessity of the power divider

power combining

in phase or out of phase

Problems of conventional power dividers

• Large size at UHF or VHF band.
• Designed to match 50 Ohm termination. ( Additional matching networks are necessary. - Increase system size )
• Symmetry -> Only equal power division ratio.

Size reduction technique (1) –> MTT-Trans (1991)

A-A’ : symmetrical axis

ring hybrid’ scattering matrix

Isolation

Size reduction technique (1) –> MTT-Trans (1991)

A-A’ : symmetrical axis

ring hybrid’ scattering matrix

• Find S-parameter
• Isolation : S31=S42=0 at f=f0
• 3dB output power division
• -> |S21|=|S41| & |S12|=|S32|
• Then, obtain

Size reduction technique (1) –> MTT-Trans (1991)

3dB power division & good matching

Size reduction technique (2) –> MTT-S (1989)

BUT -> 1. series L : high resistive losses

2. Same termination impedances

Size reduction technique (3) –> MTT-Trans (1994)

1 : Input

2 : +90 output

4 : -90 output

3 : isolation

1 : Input

2 : +90 output

4 : -90 output

3 : isolation

series L : 3개

series L : 1개

Reduce series L

Size reduction technique (3) –> MTT-Trans (1994)

Remove series L (1980 )

But limited to equal-power split-ring hybrid

• Excitation at port 2 (V)
• Transmission line Eq
• node 1&2, node 3&1
• (2)node Eq
• node 1, node 2, node 2&GND, nod 2&3
• (3)3dB power division
• (4)

(1) ~ (4) Then,

Power division & isolation

matching

Arbitrary power division & termination impedances (2) –> MTT-Trans (1997)

Lossless ->

3 port isolation & 1 port matched ->

S31=0 & excitation for port 1 & put

wave ratio = b1 : b2 = S21 : S41

Under the assumption S31=0, the characteristic admittances Y1, Y4 determined

Arbitrary power division & termination impedances (2) –> MTT-Trans (1997)

• excitation for port 3
• The dummy arms Y2 and Y3 makes port 2&4 isolation
• If isolation is not ideal -> small power flows forward to port 3
• For these two waves to be isolated from port 1, two conditions must be satisfied.
• The two waves must have a phase shift of 180degree against each other,
• ->
• The wave ratio must be b2 : b1 as shown left.
• Reciprocal 하므로

m=n=p=k & b1:b2=1:1 => conventional ring hybrid

Arbitrary power division & termination impedances (2) –> MTT-Trans (1997)

Port 1 : n=1 -> 50 Ohm

Port 2 : m=1.1 -> 45.45 Ohm

Port 3 : p=0.7 -> 71.429 Ohm

Port 4 : k=0.8 -> 62.5 Ohm

Power spilt ratio : 2dB ( 20log(b1/b2) =2dB )

Simulation Result

S21=-2.124dB , S41=-4.124dB

S43=-2.124dB , S23=-4.124dB

S31=-158..656dB , S42=-160.656dB

Power division

Isolation

matching

Conclusion

• Power divider’s size may be reduce
• ( less than quarter wave line,
• & lumped element )
• We can remove matching network with Arbitrary termination Impedance & Arbitrary power division power divider.
• -> realize small size system

References

• Three-Port 3-dB Power Divider Terminated by Different Impedances and Its Application to MMIC’s , IEEE MTT Trans. 1999
• Arbitrary Termination Impedances, Arbitrary Power Division, and Small-Sized Ring Hybrids, IEEE MTT Trans. 1997
• Miniaturized 3-dB ring hybrid terminated by arbitrary impedances, IEEE MTT Trans. 1994
• Design of new hybrid-ring, directional coupler using λ/8 or λ/6 sections, IEEE MTT Trans. 1991
• 180° lumped element hybrid, IEEE MTT-S.1989