AD8138 Datasheet, PDF (1/16 Pages) Analog Devices – Low Distortion Differential ADC Driver

FEATURES
Easy to Use Single-Ended-to-Differential Conversion
Adjustable Output Common-Mode Voltage
Externally Adjustable Gain
Low Harmonic Distortion
–94 dBc—Second, –114 dBc—Third @ 5 MHz into
800 ⍀ Load
–87 dBc—Second, –85 dBc—Third @ 20 MHz into
800 ⍀ Load
–3 dB Bandwidth of 320 MHz, G = +1
Fast Settling to 0.01% of 16 ns
Slew Rate 1150 V/␮s
Fast Overdrive Recovery of 4 ns
Low Input Voltage Noise of 5 nV/÷Hz
1 mV Typical Offset Voltage
Wide Supply Range +3 V to ؎5 V
Low Power 90 mW on 5 V
0.1 dB Gain Flatness to 40 MHz
Available in 8-Lead SOIC and MSOP Packages
APPLICATIONS
ADC Driver
Single-Ended-to-Differential Converter
IF and Baseband Gain Block
Differential Buffer
Line Driver
Low Distortion
Differential ADC Driver
AD8138
PIN CONFIGURATION
–IN 1
8 ^+IN
V_OCM 2
7 NC
V+ 3
6 V–
+OUT 4
5 –OUT
AD8138
NC = NO CONNECT
TYPICAL APPLICATION CIRCUIT
+5V
499⍀
499⍀
V_IN
+
V_OCM
AD8138
499⍀
–
+5V
AIN ^{AVDD DVDD}
ADC
AIN _{AVSS VREF}
DIGITAL
OUTPUTS
499⍀
PRODUCT DESCRIPTION
The AD8138 is a major advancement over op amps for differential
signal processing. The AD8138 can be used as a single-ended-
to-differential amplifier or as a differential-to-differential
amplifier. The AD8138 is as easy to use as an op amp, and
greatly simplifies differential signal amplification and driving.
Manufactured on ADI’s proprietary XFCB bipolar process, the
AD8138 has a –3 dB bandwidth of 320 MHz and delivers a
differential signal with the lowest harmonic distortion available
in a differential amplifier. The AD8138 has a unique internal
feedback feature that provides balanced output gain and phase
matching, suppressing even order harmonics. The internal feed-
back circuit also minimizes any gain error that would be associated
with the mismatches in the external gain setting resistors.
The AD8138’s differential output helps balance the input-to-
differential ADCs, maximizing the performance of the ADC.
The AD8138 eliminates the need for a transformer with high
performance ADCs, preserving the low frequency and dc infor-
mation. The common-mode level of the differential output is
adjustable by a voltage on the V_OCM pin, easily level-shifting the
input signals for driving single-supply ADCs. Fast overload
recovery preserves sampling accuracy.
The AD8138 distortion performance makes it an ideal ADC driver
for communication systems, with distortion performance good
enough to drive state-of-the-art 10-bit to 16-bit converters at
high frequencies. The AD8138’s high bandwidth and IP3 also
make it appropriate for use as a gain block in IF and baseband
signal chains. The AD8138 offset and dynamic performance
make it well suited for a wide variety of signal processing and
data acquisition applications.
The AD8138 is available in both SOIC and MSOP packages for
operation over –40∞C to +85∞C temperatures.
REV. E
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