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Low-pass filters/amplifiers offer guaranteed matching

Milpitas, Calif. — Linear Technology has introduced a family of four high-performance, dual fixed-frequency, low-pass active filters/amplifiers targeting a range of wireless communications and industrial signal processing equipment applications.

The LT6604-xx consists of two matched, fully differential amplifiers, combined with 4th order filters approximating a Chebyshev low-pass response. Each device offers guaranteed matched amplitude and phase characteristics, for current and next-generation wireless communication standards such as LTE (Long Term Evolution) and WiMAX, while addressing the challenge of channel matching.

The LT6604-xx family is comprised of the following devices:

  • LT6604-2.5: 2.5-MHz cutoff frequency
  • LT6604-5: 5-MHz cutoff frequency
  • LT6604-10: 10-MHz cutoff frequency
  • LT6604-15: 15-MHz cutoff frequency

These products are said to 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 2 Vp-p and an adjustable common-mode voltage, allowing it to interface to a wide range of A/D converters.

The LT6604-xx combines baseband channel filtering and gain matching to form a compact solution for high-performance I/Q demodulators. These devices can be used as pre-filters for multi-channel A/D converters. Each filter in the LT6604 offers better than 0.9 dB 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 3-V, 5-V and ±5-V supply operation. Each differential filter/amplifier gain can be set from 0 dB to more than 12 dB using a pair of external resistors.

The LT6604 draws a total quiescent supply current of 26 mA per channel. All four devices are offered in a 34-lead, 4 x 7-mm QFN surface-mount package with identical pinouts.

Pricing: Commercial-grade devices with guaranteed operation from 0°C to 70°C, are priced at $6.50 each, and industrial-grade versions are rated for -40°C to 85°C and priced at $7.45 each, in quantities of 1,000.
Availability: The LT6604-xx devices are available immediately from stock.

Product information: LT6604-2.5, LT6604-5, LT6604-10, and LT6604-15

Linear Technology , www.linear.com

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