2.4GHz Single Balanced Mixer Andrew Bacon Jacqueline Griffin John Stone

Mixer Specifications IF Frequency: 140 MHz RF Frequency: MHz RF Power: -10 dBm LO Frequency: MHz LO Power: 8 dBm Conversion Loss: > -9.5 dB LO-RF Rejection: < -20 dB LO-IF Rejection: <-30 dB

Mixer Design

Balun Design and Simulation Used an  r of 2.9 for second layer to compensate for it being buried.

Diode Model and Simulation

Matching Design and Simulation Find input impedance of diodes at 2.4 GHz Design single stub network between diodes and balun Let simulator optimize LC filter at output

Mixer Layout LO Return IF Block LO Port RF Port Diode Matching Circuits LC LPF Coupler IF Port Diode Ghetto Lettering 2.6 in 1.7 in

Resulting Board (Problems) All holes that were supposed to be connected to ground were not All holes that were not supposed to be connected to ground were Missing parts of Traces

Mixer Board Top ViewBottom View

Measurement Methodology Down Converter Used spectrum analyzer because it has low error (~.1dB) Low frequency cable was taken out of measurement through calibration High frequency cable was taken out of measurement by measuring the response of the cable after measuring the mixer Used spectrum analyser to measure IF rejection

Measurement Diagram (Down Converter) IFRF LO GHz Vector Network Analyzer RFLO LO Signal Generator

Downconversion Results RF Freq (GHz) LO Freq (GHz) Conv. Loss LO-IF Isolation (dBm) MeasurementsSimulation

Downconverter Measurements RF Freq = 2.40 GHzRF Freq = 2.44 GHz RF Freq = GHz

Frequency Shift Measurements Desired Frequency Response Results Adjusting the IF return led to being able to shift the frequency Band up to 2.0 GHz on another board If inductor were used this adjustment would be much easier As stub is shorted to ground at end. RF freq Conversion Loss

Simulation Verification RF freq (GHz) Conversion Loss

Measurement Methodology Up Converter Used spectrum analyzer

Measurement Diagram (Up Converter) MHz GHz IFRF LO IF Signal Generator LO Signal Generator

Upconversion Spurious Levels Freq Range (GHz) Spurious Spec LO 2.26 GHz LO 2.30 GHz LO GHz LO 2.26 GHz LO 2.30 GHz LO GHz <-50 dBc < -40 dBc < -40 dBc <-30 dBc MeasurementsSimulation

Upconverter Measurements LO Freq = 2.26 GHzLO Freq = 2.30 GHz LO Freq = GHz

Upconverter Sweep Measurement LO Frequency Swept from 2.26 GHz to GHz

LO-RF Isolation

Simulations vs. Measurements Possible Reasons for inaccuracies Fabrication (~.5dB) Inaccurate  r Multilayer simulation problems with ADS

Improvements Use inductor for IF return (will allow more tuning) Verify technology parameters Verify ADS’s simulation abilities

Questions