STUDY OF RECEIVER MIXER CHARACTERISTICS.
Final rept. no. 4, 1 Jun 65-1 Aug 66,
GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION
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The report summarizes a thirteen month program concerned with the investigation of spurious product formations in conventional mixer circuits, and with the development of techniques whereby the levels of such formations could be predicted from limited measurements of mixer parameters. The interference characteristics of diode, pentode, triode, and transistor mixer types were investigated for numerous ordered arrangements of mixer dc parameters, circuit configurations, and signal injection levels. The results have demonstrated that changes in the mode of signal andor local oscillator injection, local oscillator level, mixer load conditions, or mixer dc voltages produce changes in response levels which are apparently unpredictable, and that attempts to develop prediction models based on discrete mixer parameters may be impractical. Tests were conducted on a diode mixer which verify that multiple mix products can occur due to signal andor local oscillator harmonic injection, and that the levels of such products are dependent upon the phase orientation of the injected signals. Tests were also conducted which show the effects of mixer bias voltage on response phase position. A spurious response prediction technique for diode mixers previously developed at Georgia Tech was investigated to determine if modifications and improvements could be made to reduce prediction errors, and if this technique could be successfully applied to other mixer types. Maximum-upper-bound prediction methods which might give worst-case approximations of spurious response levels were also investigated. Prediction results are presented which were derived from the actual prediction of numerous data sets on diode, pentode, triode, and transistor mixers. Author
- Electrical and Electronic Equipment