LT1206C Linear Technology, LT1206C Datasheet - Page 8

• Manufacturer Part Number: LT1206C
• Description: 250mA/60MHz Current Feedback Amplifier
• Manufacturer: Linear Technology

LT1206
SI PLIFIED SCHE ATIC
8
A
The LT1206 is a current feedback amplifier with high
output current drive capability. The device is stable with
large capacitive loads and can easily supply the high
currents required by capacitive loads. The amplifier will
drive low impedance loads such as cables with excellent
linearity at high frequencies.
Feedback Resistor Selection
The optimum value for the feedback resistors is a function
of the operating conditions of the device, the load imped-
ance and the desired flatness of response. The Typical AC
Performance tables give the values which result in the
highest 0.1dB and 0.5dB bandwidths for various resistive
loads and operating conditions. If this level of flatness is
not required, a higher bandwidth can be obtained by use
of a lower feedback resistor. The characteristic curves of
Bandwidth vs Supply Voltage indicate feedback resistors
for peaking up to 5dB. These curves use a solid line when
the response has less than 0.5dB of peaking and a dashed
PPLICATI
W
O
U
S
Q17
I FOR ATIO
U
W
SHUTDOWN
CURRENT
SOURCES
TO ALL
Q18
1.25k
W
+IN
V
V
Q1
Q3
–
+
U
Q2
Q4
–IN
Q5
Q7
line when the response has 0.5dB to 5dB of peaking. The
curves stop where the response has more than 5dB of
peaking.
For resistive loads, the COMP pin should be left open (see
section on capacitive loads).
Capacitive Loads
The LT1206 includes an optional compensation network
for driving capacitive loads. This network eliminates most
of the output stage peaking associated with capacitive
loads, allowing the frequency response to be flattened.
Figure 1 shows the effect of the network on a 200pF load.
Without the optional compensation, there is a 5dB peak at
40MHz caused by the effect of the capacitance on the
output stage. Adding a 0.01 F bypass capacitor between
the output and the COMP pins connects the compensation
and completely eliminates the peaking. A lower value
feedback resistor can now be used, resulting in a response
Q6
Q8
C
C
V
V
Q9
Q12
–
+
R
D1
D2
C
Q15
Q16
50
COMP
Q13
Q10
LT1206 • TC
Q14
Q11
V
OUTPUT
V
+
–