LT6604-2.5 Datasheet, PDF (1/16 Pages) Linear Technology – Dual Very Low Noise, Differential Amplifi er and 2.5MHz Lowpass Filter

LT6604-2.5
Dual Very Low Noise,
Differential Amplifier and
2.5MHz Lowpass Filter
FEATURES
n _{Dual Differential Amplifier with 2.5MHz Lowpass Filters}
4th Order Filters
Approximates Chebyshev Response
Guaranteed Phase and Gain Matching
Resistor-Programmable Differential Gain
n _{>86dB Signal-to-Noise (3V Supply, 1VRMS Output)}
n _{Low Distortion (1MHz, 1VRMS Output, 800Ω Load)}
HD2: 92dBc
HD3: 88dBc
n _{Specified for Operation with 3V, 5V and ±5V Supplies}
n _{Fully Differential Inputs and Outputs}
n _{Adjustable Output Common Mode Voltage}
n _{Small 4mm × 7mm × 0.75mm QFN Package}
APPLICATIONS
n _{Dual Differential ADC Driver and Filter}
n _{Single-Ended to Differential Converter}
n _{Matched, Dual, Differential Gain or Filter Stage}
n _{Common Mode Translation of Differential Signals}
n _{High Speed ADC Antialiasing and DAC Smoothing in}
Wireless Infrastructure or Networking Applications
n _{High Speed Test and Measurement Equipment}
n _{Medical Imaging}
DESCRIPTION
The LT^®6604-2.5 consists of two matched, fully differential
amplifiers, each with a 4th order, 2.5MHz lowpass filter. The
fixed frequency lowpass filter approximates a Chebyshev
response. By integrating a filter and a differential ampli-
fier, distortion and noise are made exceptionally low. At
unity gain, the measured in-band signal-to-noise ratio is
an impressive 86dB. At higher gains, the input referred
noise decreases, allowing the part to process smaller
input differential signals without significantly degrading
the signal-to-noise ratio.
Gain and phase are well matched between the two chan-
nels. Gain for each channel is independently programmed
using two external resistors. The LT6604-2.5 enables level
shifting by providing an adjustable output common mode
voltage, making it ideal for directly interfacing to ADCs.
The LT6604-2.5 is fully specified for 3V operation. The
differential design enables outstanding performance up
to a 4V_P-P signal level for a single 3V supply.
See the back page of this datasheet for a complete list of
related single and dual differential amplifiers with integrated
2.5MHz to 20MHz lowpass filters.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.v
TYPICAL APPLICATION
1580Ω
+
0.01μF
–
1580Ω
1580Ω
+
0.01μF
–
1580Ω
LT6604-2.5
+INA ₊
V_MIDA
–
V_OCMA
–INA _– ⁺
+INB
+
V_MIDB
–
V_OCMB
–INB _– ⁺
V^–
V⁺A
–OUTA
3V
50Ω
+OUTA
50Ω
V⁺B
–OUTB
3V
50Ω
+OUTB
50Ω
3V
LTC22xx
DUAL ADC
18pF AIN
DOUT
18pF AIN
DOUT
660425 TA01
Channel to Channel Gain Matching
18
50 TYPICAL UNITS
16 ^TA ^{= 25°C}
GAIN = 1
14 f_IN = 2.5MHz
12
10
8
6
4
2
0
–0.25
–0.15 –0.05 0 0.05 0.15 0.25
GAIN MATCH (dB)
660425 TA01b
660425f
1