LT6600IS8-2.5#TRPBF Linear Technology, LT6600IS8-2.5#TRPBF Datasheet - Page 9

• Manufacturer Part Number: LT6600IS8-2.5#TRPBF
• Description: IC AMP DIFF LP FLTR 2.5MHZ 8SOIC
• Manufacturer: Linear Technology

Specifications of LT6600IS8-2.5#TRPBF

• Amplifier Type: Differential
• Number Of Circuits: 1
• Output Type: Differential
• Current - Input Bias: 15µA
• Voltage - Input Offset: 5000µV
• Current - Supply: 28mA
• Voltage - Supply, Single/dual (±): 3 V ~ 11 V, ±1.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• -3db Bandwidth: -
• Slew Rate: -
• Gain Bandwidth Product: -

APPLICATIONS INFORMATION
Use Figure 4 to determine the interface between the
LT6600-2.5 and a current output DAC. The gain, or “trans-
impedance,” is defi ned as A = V
transimpedance, use the following equation:
By setting R1 + R2 = 1580Ω, the gain equation reduces
to A = R1(Ω).
The voltage at the pins of the DAC is determined by R1,
R2, the voltage on V
Consider Figure 4 with R1 = 49.9Ω and R2 = 1540Ω. The
voltage at V
DAC pins is given by:
I
49.6Ω.
Evaluating the LT6600-2.5
The low impedance levels and high frequency operation
of the LT6600-2.5 require some attention to the matching
networks between the LT6600-2.5 and other devices. The
previous examples assume an ideal (0Ω) source imped-
ance and a large (1kΩ) load resistance. Among practical
examples where impedance must be considered is the
evaluation of the LT6600-2.5 with a network analyzer.
IN
CURRENT
660025 F04
OUTPUT
A =
V
is I
DAC
DAC
IN
1580 • R1
(
R1+ R2
+
= V
= 26mV +I
I
I
IN
IN
R1
R1
or I
–
+
MID
PIN7
IN
0.01μF
, for V
–
)
. The transimpedance in this example is
Figure 4. (S8 Pin Numbers)
•
( )
R1+ R2 + 1580
Ω
IN
R2
R2
S
• 48.3Ω
MID
= 3.3V, is 1.65V. The voltage at the
R1
1
7
2
8
–
+
and the DAC output current.
LT6600-2.5
3.3V
6
3
+
–
0.1μF
4
5
OUT
+I
V
OUT
/I
IN
I
IN
IN
+
+
•
V
V
– V
– I
. To compute the
OUT
OUT
R1+ R2
R1• R2
IN
OUT
–
+
–
–
=
1580 • R1
R1 + R2
Figure 5 is a laboratory setup that can be used to charac-
terize the LT6600-2.5 using single-ended instruments
with 50Ω source impedance and 50Ω input impedance.
For a 12dB gain confi guration the LT6600-2.5 requires a
402Ω source resistance yet the network analyzer output is
calibrated for a 50Ω load resistance. The 1:1 transformer,
53.6Ω and 388Ω resistors satisfy the two constraints
above. The transformer converts the single-ended source
into a differential stimulus. Similarly, the output of the
LT6600-2.5 will have lower distortion with larger load
resistance yet the analyzer input is typically 50Ω. The 4:1
turns (16:1 impedance) transformer and the two 402Ω
resistors of Figure 5, present the output of the LT6600-2.5
with a 1600Ω differential load, or the equivalent of 800Ω
to ground at each output. The impedance seen by the
network analyzer input is still 50Ω, reducing refl ections in
the cabling between the transformer and analyzer input.
Differential and Common Mode Voltage Ranges
The rail-to-rail output stage of the LT6600-2.5 can process
large differential signal levels. On a 3V supply, the output
signal can be 5.1V
signals as large as 8.8V
dissipation in the internal circuitry, the user must limit
differential signal levels to 9V
The two amplifi ers inside the LT6600-2.5 have indepen-
dent control of their output common mode voltage (see
the Block Diagram section). The following guidelines will
optimize the performance of the fi lter.
NETWORK
ANALYZER
SOURCE
50Ω
53.6Ω
COILCRAFT
TTWB-1010
1:1
Figure 5. (S8 Pin Numbers)
P-P
388Ω
388Ω
. Similarly, a 5V supply can support
P-P
1
7
2
8
LT6600-2.5
+
–
. To prevent excessive power
–2.5V
3
6
2.5V
P-P
+
–
0.1μF
0.1μF
4
5
.
LT6600-2.5
402Ω
402Ω
COILCRAFT
TTWB-16A
4:1
NETWORK
ANALYZER
INPUT
660025fe
660025 F05
50Ω
9