Programmable RF transceiver features a 135 dBm link budget

Semtech Corp. has introduced a programmable radio frequency (RF) transceiver that is claiming market-leading sensitivity and features a 135 dBm link budget that is 10 dB more than competing devices.

The SX1231, which is the latest in the company's low-power transceiver platform, provides a cost-effective solution for wireless applications using the industrial, scientific and medical (ISM) frequency band like automated meter reading and home/building automation systems.

The device reduces system operations cost through its low 16 mA receive current and 33 mA transmit current which delivers longer battery life. The highly integrated transceiver uses Semtech's TrueRF technology to integrate SAW filter functionality; the device also integrates the VCO tank, PLL loop filter and an RF switch to minimize external components.

The frequency range of the SX1231 is 290 MHz-1020 MHz, which includes the 433, 868 and 915 MHz license-free ISM frequency bands. The device features an integrated packet engine that offloads RF packetization from a microcontroller, freeing up this resource or allowing a designer to choose a lower cost or lower power alternative. The packet engine provides CRC error checking, AES-128 encryption and a 66-byte FIFO.

The output power of the SX1231 is programmable in 1 dB steps from -18 dBm to +17 dBm. The transceiver can be programmed between narrow-band and wide-band communications modes without the need to modify external components. The transceiver operates with GFSK, MSK, FSK, OOK, ASK modulations types up to 300 kbps with constant RF performance over the 1.8 V to 3.7 V power supply range. It also features market-leading immunity to out-of-band interferers with 80 dB of blocking immunity and a self adaptive IIP3 from -18 dBm to 8 dBm and +35 dBm IIP2 response.

“Lower-cost ISM systems can spur new applications and markets. The SX1231 eliminates most of the passive components and the RF switch from designs, driving down the BOM costs without a sacrifice in performance,” said Marc Pegulu, Industrial Analog Product Line Manager for Semtech. “The SX1231 completes Semtech's portfolio of ultra low power RF transceivers by offering market breakthrough radio technology for sub-gigahertz applications that are seeking wide range and reliable communication.”

The SX1231 is certified for worldwide safety and transmissions regulations including the European (ETSI EN 300-220-1), the North American (FCC part 15) and Korea and Japan ARIB regulatory standards. The 5 mm x 5 mm SX1231 (QFN 24) offers designers the benefit of significant board space savings, and its small size and RoHS & WEEE compliance also contributes to energy conservation and hazardous waste reduction.

Key Features of the SX1231

  • High Sensitivity: down to -120 dBm at 1.2 kbps
  • High Selectivity: 16-tap FIR Channel Filter
  • Bullet-proof front end: IIP3 = -18 dBm at highest LNA gain and >5dBm at lowest LNA gain, IIP2 = +35 dBm, 80 dB Blocking Immunity, no Image Frequency response
  • Low current: Rx = 16 mA, Tx = 33 mA @ +10 dBm, 200nA register retention
  • Programmable RF output power: -18 to +17 dBm
  • Constant RF performance over voltage range of chip
  • FSK Bit rates up to 300 kb/s
  • FSK, GFSK, MSK, GMSK and OOK modulations

  • Packet engine with CRC, AES-128 encryption and 66-byte FIFO


The SX1231 (order code: SX1231IMLTRT) is available immediately in production quantities and is priced at $1.88 each in 3,000-piece lots. Semtech offers comprehensive design assistance, including field- and factory-based support.

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