TS616

Increasing the line level using active impedance matching

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Increasing the line level using active impedance

matching

With passive matching, the output signal amplitude of the driver must be twice the amplitude

on the load. To go beyond this limitation an active matching impedance can be used. With

this technique, it is possible to maintain good impedance matching with an amplitude on the

load higher than half of the output driver amplitude. This concept is shown in Figure 68 for a

differential line.

Figure 68.

TS616 as a differential line driver with active impedance matching

Component calculation

Let us consider the equivalent circuit for a single-ended configuration, as shown in

Figure 69.

Figure 69.

Single-ended equivalent circuit

R4

R2

Vi

Vi

Vo

Vo

RL

100

Ω

1:n

Hybrid

&

Transformer

GND

Vcc+

10

μ

100n

100n

100n

1k

1k

Rs1

Rs2

10n

1

μ

R3

R5

Vo°

Vo°

GND

Vcc+

Vcc+

+

_

+

_

GND

1/2

R1

1/2

R1

Vcc/2

R2

R3

+

_

Vi

Vo

Rs1

-1

Vo°

+

_

-1

½ RL

½ R1

R2

R3

+

_

Vi

Vo

Rs1

-1

Vo°

+

_

-1

½ RL

½ R1