Features and Benefits
- Low power
250 μA maximum supply current per amplifier
- FET input
2 pA maximum input bias current at 25°C
Extremely high input impedance
- Low noise
13 nV/√Hz voltage noise at 1 kHz
0.4 μV p-p voltage noise
(0.1 Hz to 10 Hz)
0.8 fA/√Hz current noise at 1 kHz
- High dc precision
3 μV/°C maximum offset drift
- 3 MHz bandwidth
- Unique pinout
No leakage from inputs to supply pins
Provides guarding capability
- Rail-to-rail output
- Single-supply operation
Input range extends to ground
- Wide supply range
Single-supply: 3 V to 36 V
Dual-supply: ±1.5 V to ±18 V
- Available in a compact 10-lead MSOP
Product DetailsThe AD8244 is a precision, low power, FET input, quad unity-gain buffer that is designed to isolate very large source impedances from the rest of the signal chain. The 2 pA maximum bias current, near zero current noise, and 10 TΩ input impedance introduce almost no error, even with source impedance well into the megaohms.
Many traditional operational amplifier pinouts have a supply pin that is next to the noninverting input. A guard trace must be routed between these pins to avoid leakage currents much larger than the bias current of a FET input op amp. Guard traces can be routed between pins for large packages, such as DIP or even SOIC; however, the board area consumed by these packages is prohibitive for many modern applications. The AD8244 solves this problem with a unique pinout that physically separates the high impedance inputs from the low impedance supplies and outputs of the other buffers. This configuration simplifies guarding while reducing board space, allowing high performance and high density in the same design.
The AD8244 design is focused on solving problems specific to buffers. This includes close channel-to-channel matching which allows channels of the AD8244 to be used in differential signal chains with minimal error. With its low voltage noise, wide supply range, and high precision, the AD8244 is also flexible enough to provide high performance anywhere a unity-gain buffer is needed, even with low source resistance.
The AD8244 is specified over the industrial temperature range of −40°C to +85°C. It is available in a 10-lead MSOP package.
- Biopotential electrodes
- Medical instrumentation
- High impedance sensor conditioning
- Photodiode amplifiers
Markets & Technology
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
The evaluation board design is flexible to allow for common circuit options, including source impedance and space for output loading and filtering. Most resistors and capacitors use 0805 packages. The evaluation board accommodates the AD8244 quad FET-input buffer in a 10-lead MSOP.
The AD8244 data sheet should be consulted in conjunction with this evaluation board user guide UG-650.
Tools & Simulations
ADIsimPE, which is powered by SIMetrix/SIMPLIS, is a circuit simulation suite optimized for the design and development of analog and mixed signal circuits. SIMetrix mode is ideal for the simulation of general non-switching circuits. It provides full Pspice compatibility for use with industry-standard SPICE models. SIMPLIS (SIMulation Piecewise-Linear System) mode simulates the operation of switching circuits with vastly improved robustness, speed, and accuracy compared to standard SPICE. It is particularly useful for switching power supply, PLLs, and ADC/DAC applications.
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.