Transmission-Line Transformers K5TRA CategoriesClick to of editTransmission Master-Line title Transformers style • Single l/4 lines and cascades of l/4 lines • Distributed element approximations of lumped element (LC) designs • Short, highly coupled unit element structures - Ruthroff - Guanella K5TRA T.Apel 2 ¼ Clickl and to Stepped edit Master ¼ l Transformers title style • Half octave performance from single quarter-wave line transformer • Nearly 2-octave performance from 3 stepped quarter-wave lines • Comparison for 50 to 100222.060 transformation MHz Beacon (BW also depends on this) l/4 Z3 l/4 Z0 = SQRT(R1*R2) l/4 Z1 l/4 Z2 R1 R2 R1 R2 R1 > Z1 > Z2 > Z3 > R2 ¼ l Z INVERTER STEPPED Z TRANSFORMER K5TRA T.Apel 3 SteppedClick to ¼ leditTransformer Master title Calculation style DOWNLOAD FROM: http://k5tra.net/ K5TRA T.Apel 4 TransmissionClick to edit-Line MasterTransformer title – styleElements 1:1 1:1 = CONVENTIONAL TRANSMISSION-LINE TRANSFORMER TRANSFORMER 1:1 SHORT (< l/8) LINE = NO NET AKA COMMON A MODE CHOKE CURRENT BALUN SYMBOLIC PHYSICAL K5TRA T.Apel 5 Click toRuthroff edit MasterTransformers title style • Transmission line ‘unit’ element • Physically short lines (length < l / 8) • Analysis based on currents 2 • R1 / R2 = (I2 / I1) = 4 • Ferrite loading extends bandwidth (low end) R1 1:1 R2 K5TRA T.Apel 6 ClickRuthroff to editType Master 9:1 Transformer title style • Transmission line ‘unit’ elements • Physically short lines (length < l / 8) • Analysis based on currents 2 • R1 / R2 = (I2 / I1) = 9 • Ferrite loading extends bandwidth (low end) R1 1:1 R2 1:1 K5TRA T.Apel 7 ClickVarious to Unbalancededit Master Transformers title style • Transmission line unit element building blocks • Parasitic even mode 222.060 MHz Beacon characteristic impedance should be large (k 1) • Z ratio available as squares of integer ratios • First order analysis on basis of port current ratio • Multiple line structures must have at least one shared current path • DC path is present K5TRA T.Apel 8 ClickGuanella to edit(4:1) BalancedMaster Transformer title style • Two ‘unit’ elements can be used to form a balanced 4:1 transformer • Analysis based on currents 2 • R1 / R2 = (I2 / I1) = 4 • Ferrite loading extends bandwidth (low end) 1:1 1:1 NO NO NO EVEN-MODE EVEN-MODE EVEN-MODE 1:1 1:1 CONVENTIONAL GUANELLA 4:1 GUANELLA 4:1 4:1 BALANCED SYMBOLIC PHYSICAL TRANSFORMER K5TRA T.Apel 9 ClickSeveral to edit Balanced Master Transformers title style • Transmission line unit element building blocks • Parasitic even mode characteristic impedance should be large (k 1) • Z ratio available as squares of integer ratios • First order analysis on basis of port current ratio • Multiple line structures must have at least one shared current path • DC path is present K5TRA T.Apel 10 ClickGuanella to Transformeredit Master and Choketitle styleBalun • Pushpull PA match example • Ferrite loaded ‘unit’ elements • Guanella transformer from coax • Choke balun (1:1) from coax K5TRA T.Apel 11 MoreClick Guanella to editTransformers Master title in PA styleOutput • Guanella transformer from coax • ‘Unit’ elements with and without ferrite loading K5TRA T.Apel 12 ClickCoupled to edit Lines Master - Symmetric title style • Two transmission-line modes - Even (or common) mode - Odd (or differential) mode • Impedances set coupling level METAL METAL DIELECTRIC METAL K5TRA T.Apel 13 Click toCoupling edit Master Coefficient title style • Zoo sets the desired Zo • Zoe should be large ! 222.060 MHz Beacon K5TRA T.Apel 14 ClickCoupled to edit Lines Master - Asymmetric title style • Asymemetric coupled lines - Two modes: C and p - Similar to ‘Even’ and ‘Odd’ • Impedances set coupling level METAL METAL DIELECTRIC METAL K5TRA T.Apel 15 ClickCoupled to edit Lines Master - Asymmetric title style • Broadside coupling is better • Asymmetric: slightly unbalanced METAL METAL DIELECTRIC METAL K5TRA T.Apel 16 Click toCoax edit Over Master Ground title style • Coax coupling is very good • Asymmetric: slightly unbalanced COAX DIELECTRIC METAL K5TRA T.Apel 17 CouplingClick Coefficient to edit Master Relationship title tostyle Zoe/Zoo K5TRA T.Apel 18 CouplingClick toCoefficient edit Master Relationship title style to Cm/C K5TRA T.Apel 19 IdealClick Ruthroff to editLoss Master vs Length title (and style Zo) i 2i 4:1 RUTHROFF i Loss (dB) Loss MISMATCH LOSS Length (degrees) • Analysis of original 4:1 Ruthroff transformer (k = 1) • Normalized port impedances (1 and 4) • Best BW from Zo=2 • Lowest loss over less BW from Zo=1 K5TRA T.Apel 20 ClickRuthroff to editLoss Master vs Length title (and style k) Zoo = 1 UNCOMPENSATED K5TRA T.Apel 21 ClickRuthroff to editLoss Master vs Length title (and style k) Zoo = 2 UNCOMPENSATED K5TRA T.Apel 22 ClickRuthroff to editLoss Master vs Length title (and style k) Zoo = 3 UNCOMPENSATED K5TRA T.Apel 23 RuthroffClickTransformer to edit Master Frequency title Compensation style • Non-ideal coupling is modeled by leakage and magnetizing inductance • CS provides DC block and low frequency compensation MODEL FOR (k<1) • CP1 and CP2 provide high frequency UNDERCOUPLED LINES compensation • If coupling is poor, or Zoo is not optimal, Cp can be used to tune the transformer for the desired frequency band FREQUENCY COMPENSATION K5TRA T.Apel 24 ClickRuthroff to editLoss Master vs Length title (and style k) Zoo = 1 COMPENSATED K5TRA T.Apel 25 ClickRuthroff to editLoss Master vs Length title (and style k) Zoo = 2 COMPENSATED K5TRA T.Apel 26 ClickRuthroff to editLoss Master vs Length title (and style k) Zoo = 3 COMPENSATED K5TRA T.Apel 27 RuthroffClick toTransformer edit Master Test title Laminates style 9:1 TRANSFORMER 4:1 TRANSFORMER K5TRA T.Apel 28 FlipClick Chip to Multiband edit Master PA with title Ruthroff style4:1 RUTHROFF 4:1 TRANSFORMER K5TRA T.Apel 29 RuthroffClick toRelationship edit Master to Auto title Transformers style i 2i i i 2i N·i RUTHROFF 4:1 i UNBALANCED TRANSFORMER • The Ruthroff structure can be i (N-1)·i redrawn as an auto RATIO TURNS N:1 transformer special case RUTHROFF 4:1 GENERAL N:1 (N=2). SHOWN AS AUTO UNBALANCED AUTO • Transformation can be set by TRANSFORMER TRANSFORMER setting the tap (1/N is tapped fraction of total primary) K5TRA T.Apel 30 GuanellaClick toRelationship edit Master to Auto title Transformers style VOLTAGE VOLTAGE BALANCE BALANCE GUANELLA 4:1 BALANCED TRANSFORMER (BALBAL) • The Guanella balanced structure can be redrawn as an auto transformer special case (N=2). - note couplings – • A more general auto transformer has secondary coupled to both primary segments GUANELLA 4:1 GENERAL N:1 • Transformation can be set by setting the taps SHOWN AS AUTO BALANCED AUTO (1/N is tapped fraction of total primary) TRANSFORMER TRANSFORMER K5TRA T.Apel 31 ClickGuanella to editand MasterAuto Transformers title style GUANELLA BALANCED TRANSFORMER MODIFIED GUANELLA BALANCED (4:1 BALBAL) TRANSFORMER (2.5:1) TOP VIEW BOTTOM AUTO TRANSFORMER (9:1) VIEW K5TRA T.Apel 32 ClickWideband to edit Flip Master Chip PA title Module style • 800 MHz – 2 GHz • WCDMA operation K5TRA T.Apel 33 Click toPushpull edit Master Multimode title PA style • Laminate contains modified Guanella transformer stacked with choke balun • Full 824 - 915 MHz operation • WCDMA, EDGE, and GSM K5TRA T.Apel 34 ClickLow to V edit Pushpull Master Multimode title PA style • Low Vcc operation provided by high ratio transformer • Three metal layers are used in a 9:1 auto-transformer • Choke balun 5mm x 4mm PA MODULE ( .20” x .16” ) K5TRA T.Apel 35 ClickGaAs toPushpull edit Master PA Circuit title Blocks style ARRAY OF OUTPUT CELLS WITH INTERLEAVED MANIFOLD AND 3RD HARMONIC TUNING INTERSTAGE GUANELLA INPUT CHOKE BALUN and GUANELLA TRANSFORMER TRANSFORMER K5TRA T.Apel 36 Click to editSummary Master title style • Transmission-line transformers – 3 categories • Coupled lines – Coupling coefficient – Capacitive compensation • Unbalanced or balanced forms – Ruthroff : unbalanced – Guanella: balanced • Autotransformers • Some examples K5TRA T.Apel 37.