Impedance Matching in the Grounded Emitter Connection

Author: Leonard Krugman

As in the analysis of the grounded base connection in Chapter 3, the stability factor must be less than unity for short-circuit stability. The numerical value of δ for the typical point-contact transistor is .

This re-emphasizes the fact that the point-contact transistor in the grounded emitter connection is unstable when the output is short-circuited. The stability factor for the junction transistor is , which confirms the fact that the junction transistor is short-circuit stable in the grounded emitter connection.

The input image resistance is defined in equation 3-37 as: r₁ = . The input image resistance of the point-contact transistor is numerically equal to. Since the quantity under the square root sign is negative, r₁ is imaginary and cannot be built into conventional signal sources. For the typical junction transistor, r₁ is.

The output image resistance defined by equation 3-41 as r₂ = also is imaginary for the Doint-contact transistor. For the junction transistor, r₂ is