LTC6601CUF-2#TRPBF Linear Technology, LTC6601CUF-2#TRPBF Datasheet - Page 19

• Manufacturer Part Number: LTC6601CUF-2#TRPBF
• Description: IC FILTER/ADC DVR LP LD 20-QFN
• Manufacturer: Linear Technology

Specifications of LTC6601CUF-2#TRPBF

• Frequency - Cutoff Or Center: 27MHz
• Number Of Filters: 3
• Max-order: 2nd
• Voltage - Supply: 2.7 V ~ 5.25 V
• Mounting Type: Surface Mount
• Package / Case: 20-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Filter Type: -

Likewise, substituting the numbers for a single 5V power
supply, (V
= 100Ω, into the above equation, the input common mode
range (V
The output common mode voltage is defi ned as the aver-
age of the two outputs:
The V
mode feedback loop which internally forces V
–V
1.1 V above V
middle of a voltage divider which sets the default mid-
supply open circuit potential.
In single supply applications, where the LTC6601 is used
to interface to an ADC, the optimal common mode input
to the ADC is often determined by the ADC’s reference. If
the ADC makes a reference available for setting the input
APPLICATIONS INFORMATION
Substituting the equation for Johnson noise of a resistor (e
e
e
no
no
0V ≤ V
OUT
V
=
=
OUTCM
OCM
–. The output common mode range extends from
⎛
⎝ ⎜
⎛
⎝ ⎜
INCMR
INCM
e
e
+
ni
ni
pin sets this average by an internal common
= V
= 5V, V
• 1+
• 1+
⎛
⎝ ⎜
⎛
⎝ ⎜
–
) is between the two limits:
≤ 4.7V
OCM
to 1V below V
R2
R2
–
R1
R1
=
= 0V) with V
⎞
⎠ ⎟
⎞
⎠ ⎟
V
⎞
⎠ ⎟
⎞
⎠ ⎟
OUT
2
2
+ 2 • I
+ 2 • I
+
+ V
2
+
⎛
⎜
⎜
⎝
⎛
⎜
⎜
⎝
. The V
OUT
n
n
OCM
2
2
• R2
• R2
–
⎛
⎜
⎝
⎛
⎜
⎝
= 2.5V, and R1 = R2
OCM
2
2
+ R3
+ R3
pin sits in the
2
2
• 1+
• 1+
OUT
⎛
⎝ ⎜
⎛
⎝ ⎜
+ =
R2
R2
R1
R1
⎞
⎠ ⎟
⎞
⎠ ⎟
2
2
⎞
⎟
⎠
nR
⎞
⎟
⎠
common mode voltage, it can be directly tied to the V
pin, but must be capable of driving the input impedance of
the V
to be connected to a mid-supply potential. If an external
reference drives the V
with a high quality 0.01μF or higher capacitor to a low
impedance ground plane to fi lter any thermal noise and
to prevent common mode signals on this pin from being
inadvertently converted to differential signals.
Noise Considerations
When comparing the LTC6601 noise to other amplifi ers,
be sure to compare similar specifi cations. Competing
devices often specify noise referred to the inputs of the
amplifi er. The input referred voltage noise of the LTC6601-2
is 4.7nV/√Hz.
In addition to the noise generated by the amplifi er, the
surrounding feedback resistors also contribute noise. A
noise model is shown in Figure 5. The output spot noise
generated by both the amplifi er and the feedback compo-
nents is governed by the equation:
⎞
⎟
⎟
⎠
⎞
⎟
⎟
⎠
= 4kTR), and simplifying:
+ 2 • e
+ 8 • k • T R2 1+
OCM
⎛
⎝ ⎜
nR1
pin (R
⎛
⎜
⎝
•
⎛
⎝ ⎜
R2
⎛
⎝ ⎜
R1
VOCM
⎞
⎠ ⎟
⎞
⎠ ⎟
R2
R1
). This impedance can be assumed
2
OCM
+ 2 e
⎞
⎠ ⎟
+ R3 1+
⎛
⎝ ⎜
pin, it should still be bypassed
nR3
⎛
⎝ ⎜
• 1+
⎛
⎝ ⎜
R2
R1
LTC6601-2
⎞
⎠ ⎟
R2
2
R1
⎞
⎟
⎠
⎞
⎠ ⎟
⎞
⎠ ⎟
2
+ 2 • e
19
nR2
66012f
OCM
2