Exploring the Effects of DC Biasing and Varying Local Oscillator Levels on Mixer Linearity Performance with a Novel RF Mixer Design




Reitsma, Dale

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The mixer/detector is a fundamental component in the communications field in both the receiver and transmitter signal chains. It has been used since the earliest days of radio acting as a demodulator in a cat's-whisker radio and shifting frequencies up and down the electromagnetic spectrum in the superheterodyne receiver. In recent years it has been a significant component in an I/Q modulator and an upconverter/downconverter for today's SDR platforms. A novel RF mixer design is presented in order to test the idea of using DC biasing of the quad ring diodes in a double balanced mixer to improve the linearity performance of the mixer with a lower local oscillator level. The 1 dB compression point and the third order intercept point are measured on a standard double balanced mixer as well as the modified design to determine if any effect is present. There may be applications in mobile handset front end design as well as improved linearity performance in infrastructure that requires low power consumption parameters.



Local Oscillator, Mixer, DC Biasing, IF, LO, RF