A 200MHz to 6GHz Direct Conversion I/Q Modulator Achieves 30.9dBm Output Third-Order Intercept

Sep 14 2010 -MILPITAS, CA
  • Linear Technology introduces the LTC5588-1, a new generation ultra-high linearity direct conversion I/Q modulator that operates over a wide frequency range from 200MHz to 6GHz. The new modulator offers best-in-class linearity performance of 30.9dBm OIP3 (Output Third-Order Intercept) at 2.14GHz - without calibration. The device also has the unique capability for simple calibration by a single-pin adjustment with a DC input voltage that further optimizes its OIP3 up to 35.1dBm. The LTC5588-1's linearity performance is complemented with a noise floor of –160.6dBm/Hz at 6MHz offset, enabling transmitters to achieve unprecedented dynamic range performance.


    The LTC5588-1 offers image suppression of –56.6dBc at 2.14GHz. In addition, its carrier leakage is –39.6dBm while delivering 5dBm signal power to its output without calibration. Over the operating temperature range from –40°C to 85°C, both parameters exhibit stable behavior, varying only about ±3dB. Its performance satisfies the system requirements of the most demanding broadband wireless 4G basestations, including LTE, WiMAX, multi-carrier GSM/EDGE, W-CDMA, TD-SCDMA, CDMA-2000 and CDMA, as well as other high performance wireless applications.


    The LTC5588-1's I and Q inputs are biased to a 0.5V DC common-mode voltage that is directly compatible with commercially available D/A converters that have similar DC common-mode voltage. The I and Q inputs support signal bandwidth greater than 400MHz.


    The LTC5588-1 is powered from a single 3.3V supply with an operating current of 300mA. The device has an Enable pin, allowing the chip to power down completely. In shutdown mode, the device draws a sleep current of less than 900uA. The modulator has fast turn-on and turn-off time, at 15ns and 5ns, respectively, supporting TDD (Time Division Duplexing) mode of operation. The LTC5588-1 comes in a compact 4mm × 4mm 24-pin QFN package and is available immediately from stock, priced starting at $5.70 each in 1,000 piece quantities. For more information, visit www.linear.com/product/LTC5588.


    Summary of Features: LTC5588-1


    • Operating Frequency Range200MHz to 6GH
    • Output IP3
      • at 900MHz: –31.3 dBm
      • at 900MHz (Optimized): 35.1 dBm
    • Output IP3
      • at 2.14GHz: 30.9 dBm
      • at 2.14GHz (Optimized): 35.1 dBm
    • Output IP2 at 2.14GHz
      • 58.5 dBm
    • Easy Single-Pin Calibration To Optimize OIP3
    • Noise Floor at 6MHz Offset
      • –160dBm/Hz
    • Image Suppression at 2.14GHz
      • –56.6 dBc (uncalibrated)
    • Carrier Leakage (POUT = 5dBm)
      • –39.6 dBm
    • Low Power Consumption
      • Single 3.3V, 300mA
    • Small Package 4mm × 4mm QFN

    200MHz to 6GHz Direct Quadrature Modulator with Ultrahigh OIP3

    LTC5588-1 PR Image
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