TS615IPWT(2004) View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

TS615IPWT
(Rev.:2004)

Dual Wide-Band Operational Amplifier with High Output Current

STMicroelectronics 

Increasing the Line Level Using Active Impedance Matching

TS615

First let’s consider the unloaded system. We can assume that the currents through R1, R2 and R3 are

respectively:

2-R---V--1---i, -(--V----i---R–-----V2----o----°---)and (---V----i--R-+----3-V-----o---)-

As Vo° equals Vo without load, the gain in this case becomes:

G = -V----o----(--n---V-o----il-o----a----d----) = -1----+-----12----R----R--–----1----2--RR----------+23-------RR----------23----

The gain, for the loaded system is given by Equation 6:

GL = V-----o----(--w-----i-V-t--h-i---l-o----a----d----) = 12-- 1-----+-----12-----R---R--–----1----2-RR-----------+23-------RR----------23----

Equation 6

The system shown in Figure 74 is an ideal generator with a synthesized impedance acting as the internal

impedance of the system. From this, the output voltage becomes:

Vo = (ViG) – (Ro ⋅ Iout)

where Ro is the synthesized impedance and Iout the output current.

On the other hand Vo can be expressed as:

Equation 7

Vo

=

V

i





1

+

2---R-R---1--2--

+

RR-----23--

----------------1-----–----RR----------23--------------------

–

R---1--s---–-1---I-RR----o------23-u-----t

Equation 8

By identification of both Equation 7 and Equation 8, the synthesized impedance is, with Rs1=Rs2=Rs:

Ro = 1-----–R-----RR-s---------23----

Equation 9

Figure 75: Equivalent schematic. Ro is the synthesized impedance

Ro

Iout

Vi.Gi

1/2RL

33/36

Share Link: