FREQUENCY CONVERSION BY A NONLINEAR ADMITTANCE 



24 

 22 

 20 

 18 



16 



1415 



14 



^t2 

 u 



LU 



Q 



10 



Z 8 

 < 



(J 



2 

 



-2 



-4 



6 

 X 



10 



12 



Fig. 8 — Gain of inverting modulator, glG^ = 0.3. 



zero. When the midband gain is 15 db, Figs. 7 and 8 show that the gain 

 variation is 2.0 db in the nonin verting case and 2.7 db in the inverting 

 case. When y is zero these variations are reduced to 0.8 db and 1.0 db 

 respectively for the same midband gain. The nonlinear resistor therefore 

 degrades the performance and, assuming complete freedom in the choice 

 of X, a greater bandwidth can be obtained if it is absent. 



PREFERRED NONLINEAR ELEMENTS 



Thus we see that, under the requirement that a conjugate match exist 

 at the terminals of the 4-pole, the nonlinear resistor contributes little 

 to the gain of a nonlinear capacitor modulator while the nonlinear capaci- 

 tor is of little benefit in a nonlinear resistor converter. In a modulator 

 having appreciable gain, the degree of nonlinearity permissible in the 

 nonlinear resistor is quite small. For gains exceeding 15 db, y must be 

 less than 0.2. Such a nonlinear resistor used alone would have a con- 



