SIGNAL ENHANCEMENT TECHNIQUES.
Quarterly progress rept. no. 1, 1 May-31 Jul 66,
RADIO CORP OF AMERICA NEW YORK ADVANCED COMMUNICATIONS LAB
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A variable gamma parametric mixer was developed in which the co-channel intermodulation components were substantially reduced over that obtainable in conventional mixers. The basic technique relies on achieving a prescribed nonlinearity through the use of selected diodes and various local oscillator drive conditions, so that the device harmonic content is controlled. A reversal of phase occurs identical to the intermodulation products without affecting the desired output frequencies, thereby resulting in a distortion cancellation. Results show that two - 20 dBm equal level signals produce intermodulation products which are greater than 60 dB below the output level. The intermodulation distortion of conventional mixers and amplifiers is outlined in Appendix B. The theory indicated that all distortion products could be related to the power saturation of the device under test. In addition, a study of low resistor mixers was initiated in which it directly appears that selected hot carrier diodes, under fully pumped conditions, could yield a O dB conversion loss image frequency properly terminated. A technique has also been reported in which a phase sensitive degenerate parametric amplifier could be utilized to substantially increase the signal to noise ratio of a given receiver. Author
- Electrical and Electronic Equipment