THS6212 Datasheet, PDF (34/48 Pages) Texas Instruments – Differential, Line-Driver Amplifier

THS6212
SBOS758 – MAY 2016
www.ti.com
When using a synthetic output impedance circuit (see Figure 84), a significant drop in bandwidth occurs from the
specification provided in the Electrical Characteristics tables. This apparent drop in bandwidth for the differential
signal is a result of the apparent increase in the feedback transimpedance for each amplifier. This feedback
transimpedance equation is given by Equation 16:
Z_FB = R_F ´
1+2´
R_S
R_L
+
R_S
R_P
1+2´
R_S
R_L
+
R_S
R_P
-
R_F
R_P
(16)
To increase the 0.1-dB flatness to the frequency of interest, adding a serial RC in parallel with the gain resistor
may be needed, as shown in Figure 87.
R_S
D1
THS6212
R_F
R_P
R_M
V_IN
R_G
R_P
C_M
R_F
Z_LINE
100 W
D2
R_S
THS6212
Copyright © 2016, Texas Instruments Incorporated
Figure 87. 0.1-dB Flatness Compensation Circuit
8.2.2.2.2 Computing Total Driver Power for Line-Driving Applications
The total internal power dissipation for the THS6212 in a line-driver application is the sum of the quiescent power
and the output stage power. The THS6212 holds a relatively constant quiescent current versus supply
voltage—giving a power contribution that is simply the quiescent current times the supply voltage used (the
supply voltage is greater than the solution given in Equation 15). The total output stage power can be computed
with reference to Figure 88.
V_CC
I_AVG
=
I_P
CF
R_T
Figure 88. Output Stage Power Model
34
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