lt6600cs8-5-trpbf Linear Technology Corporation, lt6600cs8-5-trpbf Datasheet - Page 12

• Manufacturer Part Number: lt6600cs8-5-trpbf
• Description: Very Low Noise, Differential Amplifier And 10mhz Lowpass Filter
• Manufacturer: Linear Technology Corporation

LT6600-10
Example: With the IC removed and the 25Ω resistors
grounded, measure the total integrated noise (e
spectrum analyzer from 10kHz to 10MHz. With the IC
inserted, the signal source (V
input resistors grounded, measure the total integrated
noise out of the filter (e
nected, set the frequency to 1MHz and adjust the ampli-
tude until V
amplitude, V
A = V
noise (e
Table 1 lists the typical input referred integrated noise for
various values of R
Figure 8 is plot of the noise spectral density as a function
of frequency for an LT6600-10 with R
fixture of Figure 7 (the instrument noise has been sub-
tracted from the results).
Table 1. Noise Performance
The noise at each output is comprised of a differential
component and a common mode component. Using a
transformer or combiner to convert the differential out-
puts to single-ended signal rejects the common mode
12
APPLICATIO S I FOR ATIO
PASSBAND
GAIN (V/V)
e
IN
4
2
1
OUT
=
IN
/V
) as:
V
IN
IN
( ) – ( )
IN
e
. Now compute the input referred integrated
O
OUT
100Ω
200Ω
402Ω
measures 100mV
R
R
R
2
IN
IN
A
IN
Figure 7. (S8 Pin Numbers)
, and compute the passband gain
1
7
2
8
IN
U
e
LT6600-10
+
S
.
–
– 2.5V
INTEGRATED NOISE
2.5V
6
3
INPUT REFERRED
10kHz TO 10MHz
2
+
–
O
0.1μF
0.1μF
). With the signal source con-
U
24μV
34μV
56μV
4
5
RMS
RMS
RMS
IN
) disconnected, and the
P-P
25Ω
25Ω
. Measure the output
W
COILCRAFT
TTWB-1010
IN
= 402Ω using the
1:1
INPUT REFERRED
NOISE dBm/Hz
SPECTRUM
–149
–146
–142
ANALYZER
U
INPUT
S
) of the
50Ω
6600 F07
noise and gives a true measure of the S/N achievable in the
system. Conversely, if each output is measured individu-
ally and the noise power added together, the resulting
calculated noise level will be higher than the true differen-
tial noise.
Power Dissipation
The LT6600-10 amplifiers combine high speed with large-
signal currents in a small package. There is a need to
ensure that the dies’s junction temperature does not
exceed 150°C. The LT6600-10 S8 package has Pin 6 fused
to the lead frame to enhance thermal conduction when
connecting to a ground plane or a large metal trace. Metal
trace and plated through-holes can be used to spread the
heat generated by the device to the backside of the PC
board. For example, on a 3/32" FR-4 board with 2oz
copper, a total of 660 square millimeters connected to Pin
6 of the LT6600-10 S8 (330 square millimeters on each
side of the PC board) will result in a thermal resistance,
θ
Table 2. LT6600-10 SO-8 Package Thermal Resistance
TOPSIDE
JA
(mm
1100
330
, of about 85°C/W. Without the extra metal trace
COPPER AREA
35
35
0
2
)
BACKSIDE
35
30
25
20
15
10
5
0
(mm
1100
0.1
330
35
0
0
SPECTRAL DENSITY
2
)
INTEGRATED
BOARD AREA
FREQUENCY (MHz)
1.0
NOISE
(mm
2500
2500
2500
2500
2500
Figure 8
2
)
10
(JUNCTION-TO-AMBIENT)
THERMAL RESISTANCE
6600 F08
100°C/W
105°C/W
65°C/W
85°C/W
95°C/W
100
140
120
100
80
60
40
20
0
6600fa