The ADA4927-1 (single) and ADA4927-2 (dual) current feedback differential ADC drivers offer excellent noise and distortion performance at very low quiescent power consumption (20 mA/channel), even at gains of 20 dB to 40 dB. The SFDR of the ADA4927 at 70 MHz operation is 80 dB. The ADA4927 can be used in either single-ended-to-differential or differential-to-differential configurations. An internal common-mode feedback loop, independent of the differential amplifier feedback path, allows the user to perform commonmode level translation, as well as common-mode noise rejection. It can operate on single supplies from 3.3 V to 5 V, or on dual supplies up to ±5 V. The ADA4927 is specified to operate over the –40°C to +105°C temperature range. The ADA4927-1 is available in a 16-lead LFCSP, and the ADA4927-2 is available in a 24-lead LFCSP. The ADA4927 is pin-to-pin compatible with the ADA4932, ADA4937, ADA4938, and ADA4939 differential ADC drivers.

The ADA4927 is designed for driving high performance, high speed ADCs including the AD9246, a monolithic, single 1.8 V supply, 14-bit, 80 MSPS/105 MSPS/125 MSPS ADC.

ADA4927 Features

• Low harmonic distortion
  • –117 dBc HD2 @ 10 MHz
  • –85 dBc HD2 @ 70 MHz
  • –75 dBc HD2 @ 100 MHz
  • –122 dBc HD3 @ 10 MHz
  • –95 dBc HD3 @ 70 MHz
  • –85 dBc HD3 @ 100 MHz
• Input-referred noise: 1.3 nV/√Hz, 23 pA/√Hz
• –3 dB large signal bandwidth of 1 GHz, G = 1
• Slew rate: 6000 V/µs, 25% to 75%
  • dB gain flatness: 250 MHz
  • Offset voltage: mV typical

Level-Translating 16-Bit ADC Driver Simplifies Signal Conditioning for High Voltage Designs

The 15 MHz AD8275 (G = 0.2) difference amplifier is able to attenuate, level shift, and drive low voltage ADCs in high voltage applications, reducing part count and board space by simplifying the signal conditioning complexities. The device includes internal, matched, precision laser-trimmed resistors that achieve 0.02% gain error and 1 ppm/°C (max) gain drift. It translates ±10 V signals to 4 V input levels, and delivers low distortion and a fast 450 ns settling time to 0.001%. The AD8275 is capable of input beyond power supply (+40 V to –35 V can be fed into the device when powered by 5 V.) In addition to eliminating high voltage power supplies, the AD8275 eliminates discrete resistor dividers, driver amplifiers, and other signal conditioning circuitry previously required to drive SAR ADCs. It is available in an 8-lead, 3 mm × 5 mm MSOP package.

The AD8275 is especially suited for driving medium speed 16-bit SAR converters, including ADI's AD7685 SAR ADC. It can be configured for differential outputs to drive differential input converters, such as the AD7688 PulSAR ADC, and can be used to drive lower sample-rate 18-bit converters, including ADI's AD7678 PulSAR ADC.

AD8275 Features

• Translation: ±10 V to 4 V
• Input overvoltage: +40 V to –35 V (V_S = 5 V)
• Fast settling time: 450 ns to 0.001%
• Rail-to-rail output
• Wide supply operation: 3.3 V to 15 V
• High CMRR: 96 dB typ
• THD + N: 106 dB typ
• Low gain drift: 1 ppm/°C max
• Low offset drift: 2.5 µV/°C

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