Datasheet

LTC6404
16
6404f
SHDN (Pin 1): When SHDN is fl oating or directly tied to
V
+
, the LTC6404 is in the normal (active) operating mode.
When Pin 1 is pulled a minimum of 2.1V below V
+
, the
LTC6404 enters into a low power shutdown state. See
Applications Information for more details.
V
+
, V
–
(Pins 2, 10, 11 and Pins 3, 9, 12): Power Supply
Pins. Three pairs of power supply pins are provided to keep
the power supply inductance as low as possible to prevent
degradation of amplifi er 2nd harmonic performance. See
the Layout Considerations section for more detail.
LTC6404-4 Driving LTC2207
16-Bit ADC (Single Tone)
LTC6404-4 Driving LTC2207
16-Bit ADC (Two Tones)
Voltage Noise Density vs
Frequency
LTC6404-4 Noise Figure vs
Frequency
LTC6404-4 TYPICAL PERFORMANCE CHARACTERISTICS
FREQUENCY (MHz)
0
–40
–20
0
40
64044 G19
–60
–80
10 20 30 50
–100
–120
–140
AMPLITUDE (dBFS)
V
S
= 3.3V
V
OUTDIFF
= 2V
P-P
V
CM
= V
OCM
= 1.25V
R
I
= 100, R
F
= 402
10.1MHz, 64k POINT FFT
f
SAMPLE
= 105Msps
FUNDAMENTAL = –1dBFS
HD2 = –98.9dBc
HD3 = –99.6dBc
FREQUENCY (MHz)
0
–40
–20
0
40
64044 G20
–60
–80
10 20 30 50
–100
–120
–140
AMPLITUDE (dBFS)
V
S
= 3.3V
V
OUTDIFF
= 2V
P-P
V
CM
= V
OCM
= 1.4V
R
I
= 100, R
F
= 402
64k POINT FFT
f
SAMPLE
= 105Msps
9.5MHz, 10.5MHz = –7dBFS
IMD3L = –100.8dBc
IMD3U = –102dBc
IMD3UIMD3L
FREQUENCY (MHz)
10
VOLTAGE NOISE DENSITY (nV/√Hz)
0.01 1 10 1000100
64044 G21
1
0.1
100
V
CM
= V
OCM
= MID-SUPPLY
V
S
= 3V
R
I
= 100, R
F
= 402
T
A
= 25°C
DIFFERENTIAL INPUT
REFERRED
COMMON MODE
FREQUENCY (MHz)
0
12
8
4
28
24
20
16
64044 G22
NOISE FIGURE (dB)
10
1000
100
V
CM
= V
OCM
= MID-SUPPLY
V
S
= 3V
T
A
= 25°C
SEE FIGURE 2 CIRCUIT
PIN FUNCTIONS
V
OCM
(Pin 4): Output Common Mode Reference Voltage.
The voltage on V
OCM
sets the output common mode
voltage level (which is defi ned as the average of the volt-
ages on the OUT
+
and OUT
–
pins). The V
OCM
pin is the
midpoint of an internal resistive voltage divider between
the supplies, developing a (default) mid-supply voltage
potential to maximize output signal swing. In general, the
V
OCM
pin can be overdriven by an external voltage refer-
ence capable of driving the input impedance presented
by the V
OCM
pin. On the LTC6404-1, the V
OCM
pin has a
input resistance of approximately 23.5k to a mid-supply