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

2. 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

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

4. Specifications and Constraints Electrical Specifications Specifications IF frequency (MHz)140 IF Bandwidth (MHz)5 RF frequency (GHz)2.4-2.485 LO frequency (GHz)2.26-2.325 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) 2.4 -2.485GHz<-50 2.485 -2.9GHz<-40 2.325 -2.4GHz<-40 1 -2.12GHz<-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

5. 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

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

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

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

9. Single Balanced Mixer (Cont.) SpecificationsSimulationRemark IF frequency (MHz)140 IF Bandwidth (MHz)55 RF frequency (GHz)2.4-2.485 LO frequency (GHz)2.26-2.325 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) 2.4 -2.485GHz<-50<-37.9X 2.485 -2.9GHz<-40<-53.7OK 2.325 -2.4GHz<-40<-47.7OK 1 -2.12GHz<-30<-37.1OK Simulation Results

10. Single Balanced Mixer (Cont.) Implementation & Measurement Layout Assembly Measurement RF Bypass Cap. Shunt Cap. Series Cap. Matching Stub Jumper Conductor 1 2 3 4

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

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

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

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

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

16. 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)2.4-2.485 LO frequency (GHz)2.26-2.325 LO power (dBm)8 (Max) IF power (dBm)0 (max) Conversion Loss (dB)>-9.5> -7.93> -11.0 LO-RF rejection (dB)<-20< -22.3< -14.2 LO-IF rejection (dB)<-30< -34.2< -11.2 Spurious Level (dBc) 2.4 -2.485GHz<-50<-37.9<- 65.0 2.485 -2.9GHz<-40<-53.7<-17.2 2.325 -2.4GHz<-40<-37.9<-65.0 1 -2.12GHz<-30<-37.1<-12.2

17. 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 Length@ IF port Diode with Large Compression

18. 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

19. 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,”