Subharmonic Mixer Design With

Ansoft Designer

Subharmonic Mixer Design With

Ansoft Designer

Tony DonisiAnsoft Road ShowAutumn, 2002

Presentation #9

Circuit And Systems Designs Are Growing More Complex

Ansoft Designer Can be used to reduce design cost and speed time-to-market for even the most challenging RF/microwave designs.

Ansoft DesignerAnsoft Designer Can be used to reduce design cost and speed time-to-market for even the most challenging RF/microwave designs.

Unique TechnologySolver on demand

CosimulationVisualization

Unique TechnologySolver on demand

CosimulationVisualization Tight Integration

Circuit, System

and Planar EM

Tight IntegrationCircuit, System

and Planar EM

Advanced CapabilitiesTransient Analysis

Load Pull3D plotting

Integrated 2D layoutIntegrated 3D layout

Advanced CapabilitiesTransient Analysis

Load Pull3D plotting

Integrated 2D layoutIntegrated 3D layout

AnsoftDesigner

AnsoftAnsoftDesignerDesigner

Circuit• Linear• Harmonic balance• Transient• Load Pull• Modulation analysis• VCO Design and analysis

Circuit• Linear• Harmonic balance• Transient• Load Pull• Modulation analysis• VCO Design and analysis

System• Frequency domain and convolution engine• BER• Modulation

System• Frequency domain and convolution engine• BER• Modulation

Planar EM• SVD FastSolve technology• Thick 3D metal• Edge Meshing• Triangular mesh• Variable thickness and εr• Advanced visualization

Planar EM• SVD FastSolve technology• Thick 3D metal• Edge Meshing• Triangular mesh• Variable thickness and εr• Advanced visualization

Overview

w Introductionw Theory w Designw Simulationw Resultsw Conclusion

Subharmonic mixers provide a design challenge due to:

• Higher frequencies• Higher order mixer products• Intricate geometries• Device modeling

Subharmonic mixers provide a design challenge due to:

• Higher frequencies• Higher order mixer products• Intricate geometries• Device modeling

Subharmonic Mixer

w Advantagesw Low frequency LOw Inherent 2LO rejectionw LO easily filtered

w Disadvantagesw Higher order spursw Higher conversion loss

RF LO 2LO

2LO - RF 2LO + RFLO

RF

Frequency

Power

Uses even harmonics of the LO for its conversion products

For a “standard” mixer, the product of interest is LO ± RF.

For a subharmonic mixer, 2LO ± RF is the desired signal.

Uses even harmonics of the LO for its conversion products

For a “standard” mixer, the product of interest is LO ± RF.

For a subharmonic mixer, 2LO ± RF is the desired signal.

nLO ± mRF

Mixer Characteristics

w LO at 14GHz w RF at 28.1GHzw Output at 100mhz w 5mil thick Alumina

w Flip-Chip surface mount antiparallel diode pair

w Spiral inductors for IFw Low-Q on Alumina

Mixer Design

LO Filter Design

OutputMatching

LOMatching

RFMatching

IF Filter Design

Stubs and matching

3D Planar Modeling of Vias, coupled lines, and “non-standard microstrip structures3D Planar Modeling of Vias, coupled lines, and “non-standard microstrip structures

Diode Characterization

Subharmonic Mixer Diodes

w Subharmonic mixers us antiparallel diode pairsw These mixers produce most of their power at “odd”“odd” products

of the input signalsw Even products are rejected due to the I-V characteristicsw m + n odd

w Attenuation of even harmonics is determined by diode “balance”

w Diode “match” is criticalw “Antiparallel” diode pairs are manufactured by many

companiesw Diodes come from the adjacent areas of the wafer so the

characteristics match very wellw Ideal for MMICSw SMT, Beamlead and flipchip versionsw Spice parameters available

Diode CharacterizationDiode Characterization

Diode CharacterizationDiode Characterization

Diode I-V Characteristics

V

I

V

I

Harmonic Mixer

Subharmonic Mixer

Harmonic mixers use single diodes or FETs, having familiar I-V characteristics

Subarmonic mixers use antiparalleldiodes, giving the I-V characteristics shown

Designer Component With Netlist Equivalent

DIODES:@ID_a %0 %1 *RS(RS=@RS) *CJ0(CJ0=@CJ0) *VJ(VJ=@VJ) *TJ(TJ=@TJ) *TNOM(TNOM=@TNOM) *XTI(XTI=@XTI) *EG(EG=@EG) *M(M=@M) *AREA(AREA=@AREA) *T(T=@T) *IS(IS=@IS) *N(N=@N) *FC(FC=@FC) *BV(BV=@BV) *IBV(IBV=@IBV) *IMAX(IMAX=@IMAX) *GC1(GC1=@GC1) *GC2(GC2=@GC2) *GC3(GC3=@GC3) *MOD(MOD=@MOD) *NOISE(NOISE=@NOISE) *FCP(FCP=@FCP) *KF(KF=@KF) *AF(AF=@AF) *SN(SN=@SN) *HARM(HARM=@HARM) *ISR(ISR=@ISR) *NR(NR=@NR) *NBV(NBV=@NBV) *NBVL(NBVL=@NBVL) *IBVL(IBVL=@IBVL) *IKF(IKF=@IKF) *TBV1(TBV1=@TBV1) *TBV2(TBV2=@TBV2) *TRS1(TRS1=@TRS1) *TRS2(TRS2=@TRS2) *TIKF(TIKF=@TIKF) *VDT0(VDT0=@VDT0)

DIODES:@ID_a %0 %1 *RS(RS=@RS) *CJ0(CJ0=@CJ0) *VJ(VJ=@VJ) *TJ(TJ=@TJ) *TNOM(TNOM=@TNOM) *XTI(XTI=@XTI) *EG(EG=@EG) *M(M=@M) *AREA(AREA=@AREA) *T(T=@T) *IS(IS=@IS) *N(N=@N) *FC(FC=@FC) *BV(BV=@BV) *IBV(IBV=@IBV) *IMAX(IMAX=@IMAX) *GC1(GC1=@GC1) *GC2(GC2=@GC2) *GC3(GC3=@GC3) *MOD(MOD=@MOD) *NOISE(NOISE=@NOISE) *FCP(FCP=@FCP) *KF(KF=@KF) *AF(AF=@AF) *SN(SN=@SN) *HARM(HARM=@HARM) *ISR(ISR=@ISR) *NR(NR=@NR) *NBV(NBV=@NBV) *NBVL(NBVL=@NBVL) *IBVL(IBVL=@IBVL) *IKF(IKF=@IKF) *TBV1(TBV1=@TBV1) *TBV2(TBV2=@TBV2) *TRS1(TRS1=@TRS1) *TRS2(TRS2=@TRS2) *TIKF(TIKF=@TIKF) *VDT0(VDT0=@VDT0)

Diode CharacterizationDiode Characterization

Diode Footprint

Diode CharacterizationDiode Characterization

Diode Schematic

Frequency Input at 14GHz, 2f located at 28GHz

Object: Used Designers advanced visualization capabilities to gain greater insight into diode electrical performance

Object: Used Designers advanced visualization capabilities to gain greater insight into diode electrical performance

Diode CharacterizationDiode Characterization

Sweep Setups

Diode CharacterizationDiode Characterization

3D Parameter Plot

Variation with Junction

Capacitance and Series Resistance

Variation with Junction

Capacitance and Series Resistance

Diode CharacterizationDiode Characterization

Amplitude of 2f Product Vs. Parameter Variation

“Ideal” Spectral

Response

“Ideal” Spectral

Response

Variation with Junction

Capacitance

Variation with Junction

Capacitance

Variation with Forward Voltage

Variation with Forward Voltage

Variation with Series

Resistance

Variation with Series

Resistance

Diode CharacterizationDiode Characterization

Mixer Design: LO filter

LO Filter DesignLO Filter Design

LO filter Real Time Tuning

LO Filter DesignLO Filter Design

Mixer Design: LO filter Results

LO Filter DesignLO Filter Design

“Custom” MCPL

This implementation will “ease” the transition from one coupler section to the next.

This implementation will “ease” the transition from one coupler section to the next.

LO Filter DesignLO Filter Design

Filter Co-Simulation Results

CoSimulation ResultsCircuit ResultsCoSimulation ResultsCircuit Results

LO Filter DesignLO Filter Design

Other Solver on DemandPossible Topologies

Designer planar EM does not have the “draw on grid” restriction. Ensemble meshes based on geometry you specify, not some pre-defined grid.

Designer planar EM does not have the “draw on grid” restriction. Ensemble meshes based on geometry you specify, not some pre-defined grid.

LO Filter DesignLO Filter Design

• Tees• Tapers• Y-Junctions• Any other topology!

• Tees• Tapers• Y-Junctions• Any other topology!

Triangle based meshing assures an accurate simulation.

Triangle based meshing assures an accurate simulation.

Stub Analysis

14GHz Stub 82.5mil Long, 3.3mil wide42GHz Stub 27.0mil Long, 2.9mil wide

14GHz Stub 82.5mil Long, 3.3mil wide42GHz Stub 27.0mil Long, 2.9mil wide

Tuning StubsTuning Stubs

Shorted Stub

Tuning StubsTuning Stubs

Designer’s Co-Simulation allows users to define their own custom 2D and 3D vias.• No restrictions on layers or geometry• No more “guesswork

Designer’s Co-Simulation allows users to define their own custom 2D and 3D vias.• No restrictions on layers or geometry• No more “guesswork

Low Pass Filter

IF FilterIF Filter

Assembling the circuit

w Stubs at key locationsw Reflect power back into diodesw Proper phasew Passed parametersw Tuning (real time)

w SMT or chip capacitorw Flip-Chip Diodew LO filter geometryw Grounded stub for DC return

Subharmonic MixerSubharmonic Mixer

Subharmonic Mixer Schematic & Layout

Subharmonic MixerSubharmonic Mixer

Subharmonic Mixer 3D Layout

Subharmonic MixerSubharmonic Mixer

This mixer can be directly inserted into another circuit, or even a system level circuit, to provide accurate system simulation. Designer’s system tool automatically extracts the necessary parameters from this circuit for use in the system simulation

This mixer can be directly inserted into another circuit, or even a system level circuit, to provide accurate system simulation. Designer’s system tool automatically extracts the necessary parameters from this circuit for use in the system simulation

Output Power Vs LO Input Power

Subharmonic MixerSubharmonic Mixer

RF Power = -20dBmRF Power = -20dBm

Output Power Vs RF Input Power

Subharmonic MixerSubharmonic Mixer

Harmonic Output

Output Power Vs RF Frequency

Subharmonic MixerSubharmonic Mixer

IF Power Vs Frequency and Parameter W5t Variation

Subharmonic MixerSubharmonic Mixer

IF Power Vs W1 and L1 Variation2 Dimensional Plot

Subharmonic MixerSubharmonic Mixer

IF Power Vs W1 and L1 Variation3 Dimensional Plot

Subharmonic MixerSubharmonic Mixer

Conclusion

w Subharmonic mixer design illustrated Designer’s advantagesw More accurate simulations w No restrictions on geometric modelsw Higher frequenciesw Higher order mixer productsw Intricate geometriesw Device modeling

w Solver on demandw Cosimulationw Visualization

Designer’s flexibility as a completely integrated circuit, system and planar tool has been demonstrated.

Designer’s flexibility as a completely integrated circuit, system and planar tool has been demonstrated.