Page 328

CHAP. 13]

317

TWO-PORT NETWORKS

Fig. 13-9 By comparing (24) and (23) we get h11 ¼ 50

13.9

h12 ¼ 0

h21 ¼ 300

h22 ¼ 0

ð25Þ

g-PARAMETERS

The terminal characteristics of a two-port circuit may also be described by still another set of hybrid parameters given in (26). I1 ¼ g11 V1 þ g12 I2

ð26Þ

V2 ¼ g21 V1 þ g22 I2 where the coefficients gij are called inverse hybrid or g-parameters. EXAMPLE 13.8

Find the g-parameters in the circuit shown in Fig. 13-10.

Fig. 13-10 This is the simple model of a field effect transistor in its linear region of operation. To find the g-parameters, we first derive the terminal equations by applying Kirchhoff’s laws at the terminals: At the input terminal:

V1 ¼ 109 I1

At the output terminal:

V2 ¼ 10ðI2  103 V1 Þ

or

I1 ¼ 109 V1

and

V2 ¼ 10I2  102 V1

(28)

g21 ¼ 102

ð28Þ

By comparing (27) and (26) we get g11 ¼ 109

13.10

g12 ¼ 0

g22 ¼ 10

TRANSMISSION PARAMETERS

The transmission parameters A, B, C, and D express the required source variables V1 and I1 in terms of the existing destination variables V2 and I2 . They are called ABCD or T-parameters and are defined by

Mahmood_Nahvi_eBook_Schaum_s_Outlines_Theory_An  
Mahmood_Nahvi_eBook_Schaum_s_Outlines_Theory_An  
Advertisement