TS615IPWT View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
TS615IPWT Datasheet PDF : 27 Pages
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TS615
Unlike the level Vo° required for a passive imped-
ance, Vo° will be smaller than 2Vo in our case. Let
us write Vo°=kVo with k the matching factor vary-
ing between 1 and 2. Assuming that the current
through R3 is negligible, it comes the following re-
sistance divider:
By fixing an arbitrary value of R2, (eq6) gives:
R3 = -------R-----2--------
1
–
2----R-----s--
RL
Ro = R-----L-k---V-+----o-2--R--R---L--s---1--
Finally, the values of R2 and R3 allow us to extract
R1 from (eq1), and it comes:
After choosing the k factor, Rs will equal to
1/2RL(k-1).
A good impedance matching assumes:
R o = 12-- RL,(eq5)
From (eq4) and (eq5) it becomes:
RR-----23-- = 1 – 2--R--R---L--s- ,(eq6)
R1 = ------------------------2----R-----2--------------------------,( eq7)
21 – RR-----23-- GL – 1 – RR-----23--
with GL the required gain.
Figure 77 : Components Calculation for
Impedance Matching Implementation
GL (gain for the
loaded system)
R1
R2 (=R4)
R3 (=R5)
Rs
Load viewed by
each driver
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
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