TS616 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'TS616' PDF : 36 Pages View PDF
Increasing the line level using active impedance matching
TS616
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---–-----V----o----°---)-
R2
a n d (---V----i--R-+---3--V----o----)
As Vo° equals Vo without load, the gain in this case becomes:
1 + 2----R-----2-- + R-----2--
G = V-----o----(--n----o---l--o----a---d----)- = ------------R-----1------------R----3--
Vi
1 – R-----2--
R3
The gain, for the loaded system is given by Equation 6:
Equation 6
1 + 2----R-----2-- + R-----2--
GL
=
V-----o----(--w-----i-t--h----l--o---a----d----)
Vi
=
12-- ----------1--R---–--1--R----------2-------R----3--
R3
The system shown in Figure 70 is an ideal generator with a synthesized impedance acting
as the internal impedance of the system. From this, the output voltage becomes:
Equation 7
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 8
Vo
=
Vi⎝⎛
1
+
2----R-----2--
R1
+
RR-----23--⎠⎞
-----------------------------------------------
–
R-----s----1---I--o----u----t
1 – R-----2--
1 – R-----2--
R3
R3
By identification of both Equation 7 and Equation 8, the synthesized impedance is, with
Rs1 = Rs2 = Rs:
Equation 9
Ro = -1----–-R----R-s---------2---
R3
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