LTC6404
16
6404f
SHDN (Pin 1): When SHDN is 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 amplier 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)
VS = 3.3V
VOUTDIFF = 2VP-P
VCM = VOCM = 1.25V
RI = 100Ω, RF = 402Ω
10.1MHz, 64k POINT FFT
fSAMPLE = 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)
VS = 3.3V
VOUTDIFF = 2VP-P
VCM = VOCM = 1.4V
RI = 100Ω, RF = 402Ω
64k POINT FFT
fSAMPLE = 105Msps
9.5MHz, 10.5MHz = –7dBFS
IMD3L = –100.8dBc
IMD3U = –102dBc
IMD3U
IMD3L
FREQUENCY (MHz)
10
VOL
TAGE
NOISE
DENSIT
Y
(nV
/√
Hz
)
0.01
1
10
1000
100
64044 G21
1
0.1
100
VCM = VOCM = MID-SUPPLY
VS = 3V
RI = 100Ω, RF = 402Ω
TA = 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
VCM = VOCM = MID-SUPPLY
VS = 3V
TA = 25°C
SEE FIGURE 2 CIRCUIT
PIN FUNCTIONS
VOCM (Pin 4): Output Common Mode Reference Voltage.
The voltage on VOCM sets the output common mode
voltage level (which is dened as the average of the volt-
ages on the OUT+ and OUT– pins). The VOCM 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
VOCM pin can be overdriven by an external voltage refer-
ence capable of driving the input impedance presented
by the VOCM pin. On the LTC6404-1, the VOCM pin has a
input resistance of approximately 23.5k to a mid-supply