Aerospace 320 MHz Low Distortion Differential Amplifier

The AD8138 is a major advancement over op amps for differential signal processing. The AD8138 can be used as a single-ended-to-differential amplifier or as a differential-to-differential amplifier. The AD8138 is as easy to use as an op amp, and greatly simplifies differential signal amplification and driving. Manufactured on ADI's proprietary XFCB bipolar process, the AD8138 has a -3 dB bandwidth of 320 MHz and delivers a differential signal with the lowest harmonic distortion available in a differential amplifier. The AD8138 has a unique internal feedback feature that provides balanced output gain and phase matching, suppressing even order harmonics. The internal feedback circuit also minimizes any gain error that would be associated with the mismatches in the external gain setting resistors.

The AD8138's differential output helps balance the input to differential ADCs, maximizing the performance of the ADC. The AD8138 eliminates the need for a transformer with high performance ADCs, preserving the low frequency and dc information. The common-mode level of the differential output is adjustable by a voltage on the VOCMpin, easily level-shifting the input signals for driving single supply ADCs. Fast overload recovery preserves sampling accuracy.

The AD8138 distortion performance makes it an ideal ADC driver for communication systems, with distortion performance good enough to drive state-of-the-art 10-bit to 16-bit converters at high frequencies. The AD8138's high bandwidth and IP3 also make it appropriate for use as a gain block in IF and baseband signal chains. The AD8138 offset and dynamic performance make it well suited for a wide variety of signal processing and data acquisition applications.

* Easy to use, single-ended-to-differential conversion * Adjustable output common-mode voltage * Externally adjustable gain * Low harmonic distortion -94 dBc SFDR @ 5 MHz -85 dBc SFDR @ 20 MHz * -3 dB bandwidth of 320 MHz, G = +1 * Fast settling to 0.01% of 16 ns