High Speed, 0.1 µV/˚C Offset Drift,
Fully Differential ADC Driver
ADA4945-1
Data Sheet
FEATURES
FUNCTIONAL BLOCK DIAGRAM
ADA4945-1
Broad power supply range: 3 V to 10 V
Wide input common-mode voltage range: −VS to +VS − 1.3 V
Rail-to-rail output
Fully specified dual power mode operation
4 mA full power mode (145 MHz)
1.4 mA low power mode (80 MHz)
Full power mode
–FB 1
+IN 2
–IN 3
12
11
10
9
DISABLE
–OUT
+OUT
Low harmonic distortion
4
V
+FB
OCM
−133 dBc HD2 and −140 dBc HD3 at 1 kHz
−133 dBc HD2 and −116 dBc HD3 at 100 kHz
Fast settling time
18-bit: 100 ns
16-bit: 50 ns
NOTES
1. CONNECT THE EXPOSED PAD TO –V .
Input voltage noise: 1.8 nV/√Hz, f = 100 kHz
115 µV maximum offset voltage from −40°C to +125°C
Adjustable output clamps for ADC input protection
S
Figure 1.
APPLICATIONS
Low power Σ-Δ, PulSAR®, and SAR ADC drivers
Single-ended to differential converters
Differential buffers
Medical imaging
Process control
Portable electronics
GENERAL DESCRIPTION
The ADA4945-1 is a low noise, low distortion, fully differential
amplifier with two selectable power modes. The device operates
over a broad power supply range of 3 V to 10 V. The low dc
offset, dc offset drift, and excellent dynamic performance of the
ADA4945-1 makes it well suited for a variety of data acquisition
and signal processing applications. The device is an ideal choice
for driving high resolution, high performance successive
approximation register (SAR) and Σ-Δ analog-to-digital
converters (ADCs) on 4 mA of quiescent current (full power
mode). The device can also be selected to operate on 1.4 mA of
quiescent current (low power mode) to scale the power
consumption to the desired performance necessary for an ADC
drive application. The adjustable common-mode voltage allows
the ADA4945-1 to match the input common-mode voltage of
multiple ADCs. The internal common-mode feedback loop
provides exceptional output balance, as well as suppression of
even order harmonic distortion products.
With the ADA4945-1, differential gain configurations are
achieved with a simple external feedback network of four
resistors determining the closed-loop gain of the amplifier.
The ADA4945-1 is fabricated using Analog Devices, Inc.,
proprietary, silicon germanium (SiGe), complementary bipolar
process, enabling the device to achieve low levels of distortion
with an input voltage noise of only 1.8 nV/√Hz (full power mode).
The ADA4945-1 is available in a RoHS-complaint, 3 mm × 3 mm,
16-lead LFCSP. The ADA4945-1 is specified to operate from
−40°C to +125°C.
Rev. 0
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