Op Amp Drives SAR ADCs to True Zero on a Single 5V Supply

Sep 8 2011 - MILPITAS, CA
  • Linear Technology introduces the LTC6360, a very low noise, high speed amplifier that can drive to 0V while maintaining high linearity on a single +5V supply. The LTC6360’s integrated ultralow noise charge pump provides an internal negative rail, eliminating the need for a negative supply. Compared to typical rail-to-rail output single-supply amplifiers that can only swing to within a few hundred millivolts of ground, the LTC6360 provides improved linearity and dynamic range in applications that benefit from a true zero output swing.

    The LTC6360 achieves outstanding precision and is ideal for driving 16- and 18-bit SAR ADCs (successive approximation register analog-to-digital converters). Input offset voltage is less than 250µV max, and noise is only 2.3nV/√Hz, providing excellent dynamic range. The device settles to 16-bits in 150ns, and achieves a closed loop –3dB bandwidth of 250MHz. Harmonic distortion (HD2/HD3) is –103dBc/–109dBc at fIN = 40kHz. The LTC6360 is unity gain stable, allowing it to be used as a buffer to achieve the lowest output noise. The output is designed to drive a series 10Ω resistor and 330pF capacitor filter network, although larger load capacitances can be driven.

    The LTC6360 is available in MSOP and 3mm × 3mm DFN 8-pin packages, and is fully specified over the commercial (0°C to 70°C), industrial (–40°C to 85°C), and extended (–40°C to 125°C) temperature ranges. Prices start at $2.19 each in 1,000 piece quantities. For more information, visit www.linear.com/product/LTC6360.

    Summary of Features: LTC6360

    • Output Swings to True Zero on Single Supply
    • 2.3nV/√Hz Noise Density
    • Fast Settling Time: 150ns, 16-Bit, 4V Step
    • 110dB SNR in 3MHz Bandwidth
    • Low Distortion, HD2 = –103dBc and
      HD3 = –109dBc for 4VP-P Output at 40kHz
    • Low Offset Voltage: 250µV Max
    • 3mm × 3mm 8-Pin DFN & 8-Lead MSOP Packages

    Integrated Low Noise Charge Pump Maximizes 16- & 18-Bit SAR ADC Dynamic Range

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