AD826ARZ-REEL7

The AD826ARZ-REEL7 from Analog Devices is a dual, high-speed voltage feedback operational amplifier that excels in applications requiring unity-gain stability, high output drive capability, and the ability to drive heavy capacitive loads. With 50 MHz bandwidth and 350 V/µs slew rate, the AD826 is suitable for many high-speed applications including video, CATV, copiers, LCDs, image scanners, and fax machines. The device features high output current drive of 50 mA minimum per amplifier and can drive unlimited capacitive loads without instability. The low power supply current of 15 mA maximum for both amplifiers makes it suitable for power-sensitive applications such as video cameras and portable instrumentation. The AD826 operates from a single +5 V supply (achieving 25 MHz bandwidth) up to ±15 V dual supplies.

The AD826 uses a voltage feedback architecture consisting of a degenerated NPN differential pair input stage driving matched PNP transistors in a folded-cascode gain stage. The output buffer stage employs emitter followers in a Class-AB configuration that delivers the necessary current to the load while maintaining low distortion levels. A key innovation is the internal compensation capacitor (CF) in the output stage that mitigates the effect of capacitive loads. With low capacitive loads, CF is bootstrapped and does not contribute to overall compensation. As capacitive loading increases, the output stage pole reduces the gain, partially engaging CF as additional compensation capacitance, which reduces the unity-gain bandwidth but maintains stability. This self-adjusting mechanism allows the AD826 to drive any value of capacitive load without oscillation, a feature rarely available in high-speed op amps.

• ADC/DAC buffer: Driving high-speed data converter inputs with minimal settling time (70 ns to 0.01%)
• Video distribution: Cable driving with excellent differential gain/phase performance (0.07%/0.11°)
• Active filters: High-speed anti-aliasing and reconstruction filters in data acquisition systems
• Imaging systems: CCD/CIS signal conditioning in scanners and copiers with capacitive loads
• Industrial signal conditioning: Buffering and amplifying sensor signals in high-speed measurement equipment