New Semtech RF Frequency Synthesizer Integrates VCO and Loop Filter in Very Small Package

SX1781 Is First in New PLL Timing Platform From Semtech. Part offers best in class phase noise performance for wireless receivers and transmitters

Camarillo, California - March 11, 2009

Semtech Corp. (Nasdaq: SMTC), a leading supplier of analog and mixed-signal semiconductors, today announced the SX1781, a completely integrated RF synthesizer in a 4mm x 4mm MLPQ16 package, which is the smallest form factor on the market. The device is the first in a platform that is designed for ultra low phase noise applications in wireless receivers.

SX1781SX1781 is a high-performance integer-N frequency synthesizer with built-in phase lock loop (PLL) circuits, including a voltage controlled oscillator (VCO) and loop filter. The SX1781 can generate a frequency output range of 1.2 GHz to 1.4 GHz with an ultra low phase noise characteristics and a very fast settling time. Additionally, the output power level of the device can be programmed to as high as +5dBm.

The chip contributes to environmentally friendly designs with one of the industry’s lowest power consumption levels and with an ultra low power sleep mode for low leakage. The small footprint of the SX1781 represents 36% in board real estate reduction when compared to competitive alternatives, and even more when used to replace a discrete PLL design. The part is RoHS & WEEE compliant, which contributes to hazardous waste reduction.

“Semtech is entering the low phase noise synthesizer market with the SX1781, because we feel there is an opportunity in this market for devices that set a new benchmark in size and cost without sacrificing phase noise, power output performance or functionality,” said Rich Lansdowne Product Group Manager of Semtech. “This device has had a great initial reception by our existing customers because they can lower costs and they can save board space, which is at a premium in these designs.”

Key Features of the SX1781

  • Frequency range: 1200 to 1400 MHz with 250kHz step
  • Fast Settling Time
  • Low Phase noise: -85 dBc/Hz @ 10 kHz offset
  • Operating voltage: 3.0 - 3.6V
  • Programmable output power: up to +5 dBm
  • Integrated VCO and loop filter
  • SPI-bus interface
  • Lock Detect output with squelch
  • Ultra-low power sleep mode
  • 4 x 4 mm MLPQ16 package
  • Pb-free and RoHS compliant

Pricing and Availability

The SX1781 (order code: SX1781IMLTRT) is available immediately in production quantities. Semtech offers comprehensive design assistance, including field- and factory-based support. Data sheets, volume pricing, and delivery quotes, as well as evaluation kits and samples, are available by contacting

About Semtech

Semtech Corporation is a leading supplier of analog and mixed-signal semiconductors for high-end consumer, computing, communications and industrial equipment. Products are designed to benefit the engineering community as well as the global community. The company is dedicated to reducing the impact it, and its products, have on the environment. Internal green programs seek to reduce waste through material and manufacturing control, use of green technology and designing for resource reduction. Publicly traded since 1967, Semtech is listed on the NASDAQ Global Select Market under the symbol SMTC. For more information, visit

Press Contact

Pauline Cadena, Public Relations, Telephone: (805) 389-2755


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