LT1994_15 Datasheet, PDF (1/20 Pages) Linear Technology – Low Noise, Low Distortion Fully Differential Input/ Output Amplifi er/Driver

FEATURES
n _{Fully Differential Input and Output}
n _{Wide Supply Range: 2.375V to 12.6V}
n _{Rail-to-Rail Output Swing}
n _{Low Noise: 3nV/√Hz}
n _{Low Distortion, 2VP-P, 1MHz: –94dBc}
n _{Adjustable Output Common Mode Voltage}
n _{Unity-Gain Stable}
n _{Gain-Bandwidth: 70MHz}
n _{Slew Rate: 65V/μs}
n _{Large Output Current: 85mA}
n _{DC Voltage Offset <2mV Max}
n _{Open-Loop Gain: 100V/mV}
n _{Low Power Shutdown}
n _{8-Pin MSOP or 3mm × 3mm DFN Package}
APPLICATIONS
n _{Differential Input A/D Converter Driver}
n _{Single-Ended to Differential Conversion}
n _{Differential Amplification with Common Mode}
Translation
n _{Rail-to-Rail Differential Line Driver/Receiver}
n _{Low Voltage, Low Noise, Differential Signal}
Processing
LT1994
Low Noise, Low Distortion
Fully Differential Input/
Output Amplifier/Driver
DESCRIPTION
The LT^®1994 is a high precision, very low noise, low distor-
tion, fully differential input/output amplifier optimized for
3V, single-supply operation. The LT1994’s output common
mode voltage is independent of the input common mode
voltage, and is adjustable by applying a voltage on the
V_OCM pin. A separate internal common mode feedback
path provides accurate output phase balancing and reduced
even-order harmonics. This makes the LT1994 ideal for
level shifting ground referenced signals for driving dif-
ferential input, single-supply ADCs.
The LT1994 output can swing rail-to-rail and is capable
of sourcing and sinking up to 85mA. In addition to the
low distortion characteristics, the LT1994 has a low input
referred voltage noise of 3nV/√Hz. This part maintains
its performance for supply voltages as low as 2.375V. It
draws only 13.3mA of supply current and has a hardware
shutdown feature that reduces current consumption to
225μA.
The LT1994 is available in an 8-pin MSOP or 8-pin DFN
package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
A/D Preamplifier: Single-Ended Input to Differential Output
with Common Mode Level Shifting
V_IN
2V_P-P
499Ω
0.1μF
499Ω
499Ω
3V
0.1μF
24.9Ω
–+
V_OCM LT1994
47pF
24.9Ω
+–
499Ω
V_OCM = 1.5V
3V _10μF
A_IN+
V_DD SD0
CONV
LTC1403A-1
SCK
A_IN–
GND ^VREF
50.4MHz
10μF
1994 TA01
LT1994 Driving an LTC1403A-1 1MHz
Sine Wave, 8192 Point FFT Plot
0
–10
f_SAMPLE = 2.8Msps
f_IN = 1.001MHz
–20 INPUT = 2VP-P,
–30
SINGLE ENDED
SFDR = 93dB
–40
–50
–60
–70
–80
–90
–100
–110
–120
0
0.35
0.70
1.05
FREQUENCY (MHz)
1.40
1994 TA01b
1994fb
1