Datasheet ADA4940-2 (Analog Devices)

Ultralow Power, Low Distortion Ful y Differential ADC Driver Data Sheet ADA4940-1/ ADA4940-2 FEATURES FUNCTIONAL BLOCK DIAGRAMS 1 Small signal bandwidth: 260 MHz E 1 1 1 Ultralow power 1.25mA ABL UT S S S S B1 S S N1I F S O –V –V –V –V + – –V –V DI – Extremely low harmonic distortion 16 15 14 13 24 23 22 21 20 19 −122 dB THD at 50 kHz ADA4940-1 –IN1 1 18 +OUT1 −96 dB THD at 1 MHz –FB 1 12 DISABLE +FB1 2 17 VOCM1 +IN 2 11 –OUT +V 3 16 –V Low input voltage noise: 3.9 nV/√Hz S1 ADA4940-2 S2 –IN 3 10 +OUT +V 4 S1 15 –VS2 14 0.35 mV maximum offset voltage –FB2 5 DISABLE2 +FB 4 9 VOCM +IN2 6 13 –OUT2 Balanced outputs 5 6 7 8 7 8 9 Settling time to 0.1%: 34 ns S S S S 10 11 12 2 2 2 2 +V +V +V +V S S
001
N2 B2 M Rail-to-rail output: −V I – F UT S + 0.1 V to +VS − 0.1 V + +V +V OCV O+
08452-
Adjustable output common-mode voltage
Figure 1.
Flexible power supplies: 3 V to 7 V (LFCSP) 0 C Disable pin to reduce power consumption F +DIN ADA4940-1 is a vailable in LFCSP and SOIC packages –20 2.5V R3 R4 + +IN 33Ω IN+ REF VDD APPLICATIONS –40 –OUT 2.7nF VOCM ADA4940-1 AD7982 2.7nF +OUT IN– Low power PulSAR®/SAR ADC drivers B) –60 GND d –IN 33Ω ( – Single-ended-to-differential conversion R1 R2 UDE –80 –DIN Differential buffers IT L C P F Line drivers –100 AM Medical imaging –120 Industrial process controls Portable electronics –140 GENERAL DESCRIPTION –160 0 20k 40k 60k 80k 100k
300 The ADA4940-1/ADA4940-2 are low noise, low distortion fully
FREQUENCY (Hz)
08452- differential amplifiers with very low power consumption. They Figure 2. ADA4940-1 Driving the AD7982 ADC are an ideal choice for driving low power, high resolution, high The ADA4940-1 is available in a Pb-free, 3 mm × 3 mm, 16-lead performance SAR and sigma-delta (Σ-Δ) analog-to-digital LFCSP, and an 8-lead SOIC. The ADA4940-2 is available in a Pb- converters (ADCs) with resolutions up to 16 bits from dc to free, 4 mm × 4 mm, 24-lead LFCSP. The pinout is optimized to 1 MHz on only 1.25 mA of quiescent current. The adjustable facilitate printed circuit board (PCB) layout and minimize level of the output common-mode voltage allows the ADA4940-1/ distortion. The ADA4940-1/ADA4940-2 are specified to ADA4940-2 to match the input common-mode voltage of operate over the −40°C to +125°C temperature range. multiple ADCs. The internal common-mode feedback loop
Table 1. Similar Products to the ADA4940-1/ ADA4940-2
provides exceptional output balance, as well as suppression of
Isupply Bandwidth Slew Rate Noise
even-order harmonic distortion products.
Product (mA) (MHz) (V/µs) (nV/√Hz)
With the ADA4940-1/ADA4940-2, differential gain AD8137 3 110 450 8.25 configurations are easily realized with a simple external feedback ADA4932-x 9 560 2800 3.6 network of four resistors determining the closed-loop gain of ADA4941-1 2.2 31 22 5.1 the amplifier. The ADA4940-1/ADA4940-2 are fabricated using
Table 2. Complementary Products to the ADA4940-1/ ADA4940-2
Analog Devices, Inc., SiGe complementary bipolar process,
Power Throughput Resolution SNR
enabling them to achieve very low levels of distortion with an
Product (mW) (MSPS) (Bits) (dB)
input voltage noise of only 3.9 nV/√Hz. The low dc offset and AD7982 7.0 1 18 98 excel ent dynamic performance of the ADA4940-1/ADA4940-2 AD7984 10.5 1.333 18 96.5 make them well suited for a variety of data acquisition and signal AD7621 65 3 16 88 processing applications. AD7623 45 1.333 16 88
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Document Outline Features Applications General Description Functional Block Diagrams Revision History Specifications VS = 5 V +DIN or –DIN to VOUT, dm Performance VOCM to VOUT, cm Performance General Performance VS = 3 V +DIN or –DIN to VOUT, dm Performance VOCM to VOUT, cm Performance General Performance Absolute Maximum Ratings Thermal Resistance Maximum Power Dissipation ESD Caution Pin Configurations and Function Descriptions Typical Performance Characteristics Test Circuits Terminology Definition of Terms Differential Voltage Common-Mode Voltage (CMV) Common-Mode Offset Voltage Differential VOS, Differential CMRR, and VOCM CMRR Balance Theory of Operation Applications Information Analyzing an Application Circuit Setting the Closed-Loop Gain Estimating the Output Noise Voltage Impact of Mismatches in the Feedback Networks Calculating the Input Impedance of an Application Circuit Terminating a Single-Ended Input Input Common-Mode Voltage Range Input and Output Capacitive AC Coupling Setting the Output Common-Mode Voltage DISABLE Pin Driving a Capacitive Load Driving a High Precision ADC Layout, Grounding, and Bypassing ADA4940-1 LFCSP Example Outline Dimensions Ordering Guide