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Dual 2.5MHz, 5MHz, 10MHz & 15MHz Lowpass Filter with Differential Amplifier & Guaranteed Matching

Sep 9 2008 - MILPITAS, CA
  • Linear Technology introduces a family of four high performance dual fixed frequency lowpass active filters/amplifiers targeting a wide range of wireless communications and industrial signal processing equipment applications.


    • LT6604-2.5: 2.5MHz Cutoff Frequency
    • LT6604-5: 5MHz Cutoff Frequency
    • LT6604-10: 10MHz Cutoff Frequency
    • LT6604-15: 15MHz Cutoff Frequency

    The LT6604-xx consists of two matched, fully differential amplifiers, combined with 4th order filters approximating a Chebyshev lowpass response. Each device offers guaranteed matched amplitude and phase characteristics, enhancing the performance of current and next generation wireless communication standards such as LTE (Long Term Evolution) and WiMAX, while addressing the challenge of channel matching. These products offer best-in-class low distortion and low noise, supporting a high system signal-to-noise performance. The differential output stage of each filter is designed to drive directly into high-sampling rate A/D converters with minimum distortion and high signal-to-noise performance. Each amplifier has a minimum output swing of 2Vp-p and an adjustable common-mode voltage, allowing it to interface to a wide range of A/D converters. The small 4mm × 7mm package offers significant space savings compared to prior discrete solutions.


    Dual Matched High Performance Broadband Filters/Drivers

    LT6604 PR Image

    The LT6604-xx combines baseband channel filtering and gain matching to form a compact solution for high-performance I/Q demodulators. Additionally, these devices can be used as pre-filters for multichannel A/D converters. Each filter in the LT6604 offers better than 0.9dB of in-band gain flatness right up to the cutoff frequency. The 4th order Chebyshev filter provides sharp roll-off while exhibiting minimum group delay response. The filter characteristics are specified for 3V, 5V and ±5V supply operation. Each differential filter/amplifier gain can be set from 0dB to more than 12dB using a pair of external resistors.


    The LT6604 draws a total quiescent supply current of 26mA per channel. All four devices are offered in a 34-lead, 4mm × 7mm QFN surface mount package with identical pinouts. Two grades are offered, including a commercial grade with guaranteed operation from 0°C to 70°C, priced at $6.50 each in 1,000-piece quantities. The industrial grade version is rated for –40°C to 85°C and priced at $7.45 each in 1,000-piece quantities. The LT6604-xx are available immediately from stock.


    Summary of Features: LT6604
    LT6604-2.5 LT6604-5 LT6604-10 LT6604-15
    Cutoff Frequency 2.5MHz 5MHz 10MHz 15MHz
    Gain Flatness 0.9dB 0.2dB 0.1dB 0.1dB
    Max Amplitude Mismatch @ fC/2 0.3dB 0.2dB 0.3dB 0.3dB
    Max Phase Mismatch @ fC/2 3.5°
    Distortion (2nd Harmonic) 92dBc 93dBc 88dBc 86dBc
    Input-Referred Integrated Noise @ Gain = 4 18uVRMS 24uVRMS 24uVRMS 36uVRMS

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