Q. Describe transistor stability parameters

The two parameters are

· The stability factor ,K

· Stability measure,ß1

These parameters determine the transistor stability

· K>1, ß1>0 -unconditionally stable

· K<1, ß1>0 -conditionally stable

· K<1, ß1<0 -unstable

This representation does not give a direct indication of the transistor model of the effects on the stability performance. To evaluate the stability parameters in terms of  the stability factor first the S parameters are converted to Y parameters.

K=(2Re(Y(11)Re(Y(22))-Re(Y(12)Y(21))/Y(12)Y(21)>1

ß1=Re(Y(22))(Go^2+Y(11)^2)-Re(Y(11)Y(12)Y(21)>0)