kh207 Fairchild Semiconductor, kh207 Datasheet - Page 5

• Manufacturer Part Number: kh207
• Description: Low Distortion Wideband Op Amp
• Manufacturer: Fairchild Semiconductor

KH207
Controlling Bandwidth and Passband Response
In most applications, a feedback resistor value of 2kΩ
will provide optimum performance; nonetheless, some
applications may require a resistor of some other value.
The response versus R
how decreasing R
response peaking, which may lead to instability).
Conversely, large values of feedback resistance tend to
roll off the response.
The best settling time performance requires the use of an
external feedback resistor (use of the internal resistor
results in a 0.1% to 0.2% settling tail). The settling
performance may be improved slightly by adding a
capacitance of 0.4pF in parallel with the feedback
resistor (settling time specifications reflect performance
with an external feedback resistor but with no external
capacitance).
Thermal Model
REV. 1A February 2001
P
P
(For positive V
(For negative V
θ
I
R
T
T
col
ca
j (pnp)
j (cir)
circuit
xxx
Figure 4: Active Current Limit Circuit (50mA)
col
= V
= 65°C/W in still air without a heatsink.
is a resistor (33Ω recommended) between the xxx collector and ±V
= [(±V
= P
= [(+V
35°C/W in still air without a Thermalloy 2268.
15°C/W in 300ft/min air with a Thermalloy 2268
(Thermalloy 2240 works equally well.)
(Include feedback R in R
out
= P
(% duty cycle)
/R
cir
pnp
load
(17.5 + θ
100°C/W
CC
CC
P
(100 + θ
T
pnp
) – V
o
j(pnp)
) – (-V
or 3mA, whichever is greater.
o
and V
(MJE170)
(MJE180)
and V
out
to pin 12
to pin 10
ca
f
CC
CC
– (I
ca
will increase bandwidth (and frequency
) + (P
12Ω
12Ω
CC
)]
) + (P
Q1
Q2
, this is the power in the npn output stage.)
R
R
2
, this is the power in the pnp output stage.)
col
100°C/W
c
c
+V
/ 1.77kΩ
-V
P
) (R
T
pnp
npn
f
j(npn)
cir
cc
cc
plot on the previous page shows
col
load
+ P
+ P
+ 6)] (I
0.01ΩF
0.01ΩF
.)
npn
npn
)θ
)θ
ca
17.5
ca
P
col
T
+ T
+ T
circuit
j(circuit)
)
°
Q3
(2N3906)
R
14.3kΩ
Q4
(2N3904)
C/W
a
a
x
.
, similar for T
+
-
T
θ
T
ca
case
ambient
j (npn)
.
CC
.
Noise Analysis
Approximate noise figure can be determined for the
KH207 using the Equivalent Input Noise plot on page 3
and the equations shown below.
Driving Cables and Capacitive Loads
When driving cables, double termination is used to
prevent reflections. For capacitive load applications, a
small series resistor at the output of the KH207 will
improve stability and settling performance.
Transmission Line Matching
One method for matching the characteristic impedance
(Z
appropriate resistor at the input or output of the amplifier.
Figure 6 shows typical inverting and non-inverting circuit
configurations for matching transmission lines.
Non-inverting gain applications:
F
where R
V
V
1
2
(Noise Figure is for the Network Inside this Box.)
=
o
) of a transmission line or cable is to place the
+
+
Figure 5: Noise Figure Diagram and Equations
-
-
10
s
s
s
R
R
kT = 4.00 x 10
V
i
i
log
n
i
1
4
Connect R
Make R
Use R
loading caused by the transmission line,
or by parasitics.
n
is inverting spot noise current (A/√Hz)
Figure 6: Transmission Line Matching
is non-inverting spot noise current (A/√Hz)
p
is spot noise voltage (V/√Hz)





=
1
+
R
R
3
R R
Z
Z
R
R
s
0
0
s
1
to isolate the amplifier from reactive
s
, R
s
n
+
g
+
R
2
n
directly to ground.
, R
4
R
n
-21
R
R
R
kT
n
R
2
R
5
s
;
6
3
g
, and R
Joules at 290°K
R
⋅
A




KH207
+
g
-
i
v
2
n
+
-
KH207
R
=
f
+
R
f
7
R
R
R
V
equal to Z
g
n
f
2
p
2
+
+
1
C
R
R
R
6
6
o
R
2
p
2 2
f
A
i
o
i
.
2
v
Z
DATA SHEET
0









R
7
V
5
o