Design of Microwave Active Devices

Appendix 8

Distributed Amplifier

The grid and drain lines are made up of the cascade combination of symmetric T cells whose impedance matrix and characteristic parameters are given below.

A8.1. Analysis of the grid line

In this case,

If we state that and , we can determine the characteristic parameters of the cell as:

[A8.1]

These equations can be simplified when the lines do not undergo losses:

[A8.2]

Characteristic impedance is a resistance and the propagation factor is a delay at low frequencies in relation to the cut-off frequency.

With low levels of losses, ω_G is very large. If we also take into account that ω ω_0G, we can write the simplified relationships for the characteristic parameters of the cells.

[A8.3]

The operation of the grid line is analyzed from the following diagram: ...