Single Balanced Mixer (SBM) Using Reduced-Size Rat-Race Coupler LO1-Group2 Jaemin Shin, Giho Park and Youngsik Hur 07/30/02

Contents Objectives Specifications and Constraints Reduced-Size Rat-Race Coupler Single Balanced Mixer Design and Modeling Simulation Results Implementation and Measurement Measurement Results Summary Conclusions

Objectives SBM Design/Modeling & Implementation Reduced-Size Rat-Race Coupler Mixer Performance Simulation & Measurement Performance Improvement & Trade-Offs

Specifications and Constraints Electrical Specifications Specifications IF frequency (MHz)140 IF Bandwidth (MHz)5 RF frequency (GHz) LO frequency (GHz) LO power (dBm)8 (min) IF power (dBm)0 (max) Conversion Loss (dB)>-9.5 LO-RF rejection (dB)<-20 LO-IF rejection (dB)<-30 Spurious Level (dBc) GHz< GHz< GHz< GHz<-30 PRC Process Board Size12inch X 12 inch Quantity per group4EA Layer Dielectric MaterialPPE εr2.85 ± 0.05 Tanδ0.002~0.003 Thickness1mm Conductor MaterialCopper Thickness50μm ± 5% Fabrication Constraints Minimum via diameter20mils Minimum Trace10mils

Reduced-Size Rat-Race Coupler Conventional Rat-Race Coupler Reduced-Size Rat-Race Coupler Parameter Calculation Features Half of λ/4 section length Absence of 3λ/4 section Needs High Impedance Severely Sensitive to Capacitance Variations More Loss Induced 2Zo

Reduced-Size Rat-Race Coupler (Cont.) Schematic S-Parameter Measurement Measurement Setup Photo.

Reduced-Size Rat-Race Coupler (Cont.) S-parameter Measurement S-Parameter Simulation Capacitor Sensitivity S11S41S31 S11 10PF 5PF 2.33PF2.27PF2PF

Single Balanced Mixer Design and Modeling Balun SOT-23 Package Parastic Model Diode Spice Model

Single Balanced Mixer (Cont.) SpecificationsSimulationRemark IF frequency (MHz)140 IF Bandwidth (MHz)55 RF frequency (GHz) LO frequency (GHz) LO power (dBm)8 (min) IF power (dBm)0 (max) Conversion Loss (dB)>-9.5> -7.93OK LO-RF rejection (dB)<-20< -22.3OK LO-IF rejection (dB)<-30< -34.2OK Spurious Level (dBc) GHz<-50<-37.9X GHz<-40<-53.7OK GHz<-40<-47.7OK GHz<-30<-37.1OK Simulation Results

Single Balanced Mixer (Cont.) Implementation & Measurement Layout Assembly Measurement RF Bypass Cap. Shunt Cap. Series Cap. Matching Stub Jumper Conductor

Single Balanced Mixer (Cont.) Measurement Results: Nonlinearity P IF = -24 dBm P IF = -8 dBm P IF = 0 dBm P IF = -16 dBm

Single Balanced Mixer (Cont.) Measurement Results : Conversion P IF = 0dBm

Single Balanced Mixer (Cont.) Measurement Results : Spurious P IF = 0dBm

Single Balanced Mixer (Cont.) Measurement Results : RF/LO P IF = 0dBm

Single Balanced Mixer (Cont.) Measurement Results : IF/LO P IF = 0dBm

Performance Summary SpecificationsSimulationMeasurementRemark IF frequency (MHz)140 Conversion Loss is close to spec. Poor Rejection due to Damaged Symmetry of Balun Large 2 nd Harmonic due to Diode Compression Large 3 rd Order Product due to Poor LO/RF Rejection IF Bandwidth (MHz)555 RF frequency (GHz) LO frequency (GHz) LO power (dBm)8 (Max) IF power (dBm)0 (max) Conversion Loss (dB)>-9.5> -7.93> LO-RF rejection (dB)<-20< -22.3< LO-IF rejection (dB)<-30< -34.2< Spurious Level (dBc) GHz<-50<-37.9< GHz<-40<-53.7< GHz<-40<-37.9< GHz<-30<-37.1<-12.2

Improvements To Optimize Balun To Optimize Capacitor/Inductor Values To Improve Symmetric Features Embedded Capacitor Via-Hole Modeling Stub Selection/Lay-out To Minimize Line IF port Diode with Large Compression

Conclusions SBM is Designed, Analyzed and Implemented Reduced-Size Rat-Race Coupler is selected as a Balun Structure Balun is Characterized and Measured Very Small Size, but Challenging to meet All the Specs Great Opportunity to Attack Mixer Stuffs

References Rajesh Mongia,Inder Bahl and Prakash Bhartia, “RF and Microwave Coupled-Line Circuits,” pp. 260 – pp. 268 T. Hirota, A. Minakawa, and M. Muraguchi, “Reduced-Size Branch-Line and Rat-Race Hybrids for Uniplanar MMIC’s,” IEEE Trans. MTT, Vol. 38, No. 3, pp. 270-pp.275, March 1990 K.Chang, I. Bahl,and V. Nair “RF and Microwave Circuit and Component Design for Wireless System,”