LT6600CS8-15 Linear Technology, LT6600CS8-15 Datasheet - Page 10

• Manufacturer Part Number: LT6600CS8-15
• Description: IC,Differential Amplifier,SINGLE,SOP,8PIN,PLASTIC
• Manufacturer: Linear Technology

Specifications of LT6600CS8-15

• Lead Free Status / Rohs Status: Not Compliant

APPLICATIONS INFORMATION
LT6600-15
Noise
The noise performance of the LT6600-15 can be evaluated
with the circuit of Figure 7.
Given the low noise output of the LT6600-15 and the
6dB attenuation of the transformer coupling network, it
is necessary to measure the noise fl oor of the spectrum
analyzer and subtract the instrument noise from the fi lter
noise measurement.
Example: With the IC removed and the 25Ω resistors
grounded, Figure 7, measure the total integrated noise (e
of the spectrum analyzer from 10kHz to 15MHz. With the
IC inserted, the signal source (V
input resistors grounded, measure the total integrated noise
out of the fi lter (e
set the frequency to 1MHz and adjust the amplitude until
V
V
compute the input referred integrated 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 func-
tion of frequency for an LT6600-15 using the fi xture of
Figure 7 (the instrument noise has been subtracted 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 outputs
to single-ended signal rejects the common mode noise and
gives a true measure of the S/N achievable in the system.
Conversely, if each output is measured individually and the
10
PASSBAND
GAIN (V/V)
IN
OUT
e
measures 100mV
IN
, and compute the passband gain A = V
4
2
1
=
(e
O
133Ω
267Ω
536Ω
R
)
IN
2
A
– (e
O
IN
). With the signal source connected,
S
.
INTEGRATED NOISE
P-P
INPUT REFERRED
10kHz TO 15MHz
)
2
. Measure the output amplitude,
109μV
36μV
62μV
RMS
RMS
RMS
IN
) disconnected, and the
INTEGRATED NOISE
INPUT REFERRED
10kHz TO 30MHz
OUT
169μV
51μV
92μV
IN
/V
RMS
RMS
) as:
RMS
IN
. Now
S
)
noise power added together, the resulting calculated noise
level will be higher than the true differential noise.
Power Dissipation
The LT6600-15 amplifi ers combine high speed with large-
signal currents in a small package. There is a need to
ensure that the die junction temperature does not exceed
150°C. The LT6600-15 package has Pin 6 fused to the
lead frame to enhance thermal conduction when connect-
ing 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
LT6600-15 (330 square millimeters on each side of the PC
board) will result in a thermal resistance, θ
85°C/W. Without the extra metal trace connected to the
V
be around 105°C/W. Table 2 can be used as a guide when
considering thermal resistance.
–
pin to provide a heat sink, the thermal resistance will
V
IN
Figure 8. Input Referred Noise, Gain = 1
45
40
35
30
25
20
15
10
5
0
0.01
R
R
IN
IN
NOISE DENSITY,
GAIN = 1x
NOISE DENSITY,
GAIN = 4x
INTEGRATED NOISE,
GAIN = 1x
INTEGRATED NOISE,
GAIN = 4x
1
7
2
8
0.1
LT6600-15
–
+
–2.5V
2.5V
6
3
FREQUENCY (MHz)
+
–
0.1μF
0.1μF
Figure 7
4
5
1
25Ω
25Ω
10
COILCRAFT
TTWB-1010
1:1
660015 F08
100
JA
180
160
140
120
100
80
60
40
20
0
SPECTRUM
ANALYZER
, of about
INPUT
660015 F07
50Ω
660015fb