Rail-to-Rail Single-Ended to Differential Amplifier Drives High Speed 16- to 18-bit SAR ADCs

Jan 25 2010 -MILPITAS, CA
  • Linear Technology introduces the LT6350, a 33MHz, low noise, rail-to-rail input and output ADC driver that settles to 16-bits in just 350ns. It is suitable for driving the latest highest performance SAR ADCs such as the LTC2393-16. The LT6350 incorporates two op amps and matched resistors to create a differential output from a single-ended high impedance input. As a result, a differential gain of 2 is achieved with no external feedback resistors, and higher gain can be obtained by using feedback resistors. Each of the two internal op amps achieve a low 1.9nV/√Hz input-referred noise density, resulting in a total output-referred noise of just 8.2nV/√Hz. The LT6350 enables high performance ADCs to achieve better than 110dB SNR over a 1MHz bandwidth.

    The input op amp is trimmed for constant low differential input-referred voltage offset over the input range to prevent VOS steps from degrading distortion. At 100kHz, the LT6350 can typically achieve –102/–97dBc HD2/HD3.

    The LT6350 provides rail-to-rail input and output range. With a single 5V supply, the outputs can swing 0.055V to 4.945V, and by using a negative supply, the outputs can each swing from 0V to 4.945V. The LT6350 operates on 2.7V to 12V total supply. The LT6350 consumes 4.8mA supply current and has a shutdown mode that allows the system to reduce power consumption during periods of inactivity.

    Fully specified commercial (0ºC to 70ºC), industrial (–40ºC to 85ºC) and extended (–40ºC to 125ºC) temperature range versions of the LT6350 are available in 8-lead MSOP and 3mm × 3mm DFN packages. Prices start at $2.59 each in quantities of 1,000 pieces. For more information, visit www.linear.com.

    Summary of Features: LT6350

    • Rail-to-Rail Input & Outputs
    • Fast Settling Time: 240ns, 0.01%, 8VP-P Output Step
    • 1.9nV/√Hz Input-Referred Op Amp Noise
    • High Impedance Input
    • No External Gain-Resistors Required
    • 2.7V to 12V Supply Operation, 4.8mA Supply Current
    • Low Power Shutdown
    • Low Distortion (HD2/HD3): –102dBc/–97dBc at 100kHz, VOUTDIFF = 4VP-P
    • High DC Linearity: < ±1LSB, 16-Bit, 8VP-P
    • 3mm × 3mm 8-Pin DFN & 8-Lead MSOP Packages

    ADC Driver: Rail-to-Rail Single-Ended Input to Rail-to-Rail Differential Output


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