Electronic Design

Op Amp Boasts Low Noise And Low Distortion

While many op amps can claim either low noise or low distortion, the AD8099 high-speed op amp promises both. It specifies a voltage noise of 0.95 nV/√Hz and a distortion of −90 dB at 10 MHz. Analog Devices claims that the AD8099 offers significantly improved noise and distortion performance compared to existing low-noise op amps.

Differences in the way vendors test for distortion make it difficult to compare op amps from different companies. Nevertheless, slew rate and full-power bandwidth are two distortion-related specifications that lend themselves to quick comparisons (see the figure). The AD8099 specifies a slew rate of 1600 V/µs and a gain bandwidth product of 5 GHz at a gain of 10. The amplifier can also deliver a slew rate of 600 V/µs, down to a gain of 2.

The AD8099's unique architecture combines the low-noise performance of the differential-pair architecture with the high slew rate of the H bridge architecture. The resulting architecture is called common-mode linearized. In addition, the 8099 employs a unusual pinout to reduce the mutual inductance and resultant distortion products caused by coupling between the positive input and negative supply pins. Also, the op amp's two output pins cut down on feedback parasitics, easing board layout and increasing the amplifier's stability.

The AD8099 is offered in a 3- by 3-mm leadframe chip-scale package (LFCSP) that reduces lead inductance, improves thermal characteristics, and saves board space. The company will also provide an S0-8 version of the op amp with the industry-standard pinout. However, the SO-8 version will have less impressive distortion specs. Pricing is $1.98 each in lots of 1000.

Analog Devices

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