TS615 ST Microelectronics, Inc., TS615 Datasheet - Page 26

• Manufacturer Part Number: TS615
• Description: Dual Wide Band Operational Amplifier
• Manufacturer: ST Microelectronics, Inc.

TS615
Unlike the level Vo
ance, Vo
us write Vo
ing between 1 and 2. Assuming that the current
through R3 is negligible, it comes the following re-
sistance divider:
After choosing the k factor, Rs will equal to
1/2RL(k-1).
A good impedance matching assumes:
From (eq4) and (eq5) it becomes:
26/27
°
will be smaller than 2Vo in our case. Let
°
=kVo with k the matching factor vary-
R2
------- -
R3
Ro
R o
°
=
required for a passive imped-
=
=
1
----------------------------- -
RL
1
-- - RL eq5
2
–
kV oRL
2Rs
---------- - eq6
RL
+
,
2R s1
,
By fixing an arbitrary value of R2, (eq6) gives:
Finally, the values of R2 and R3 allow us to extract
R1 from (eq1), and it comes:
with GL the required gain.
Figure 77 : Components Calculation for
Impedance Matching Implementation
GL (gain for the
loaded system)
Load viewed by
each driver
R2 (=R4)
R3 (=R5)
R1
Rs
R1
=
---------------------------------------------------------- - eq7
2 1
GL is fixed for the application requirements
GL=Vo/Vi=0.5(1+2R2/R1+R2/R3)/(1-R2/R3)
2R2/[2(1-R2/R3)GL-1-R2/R3]
Abritrary fixed
R2/(1-Rs/0.5RL)
0.5RL(k-1)
kRL/2
R3
–
R2
------- -
R3
=
2R2
GL 1
-------------------- -
1
–
R2
2Rs
---------- -
–
RL
–
R2
------- -
R3
,