S2-LPTX – energy-saving, cheap and functional Sub-1GHz transmitter

S2-LPTX is a new proposal of the ST Microelectronics radio transmitter with very low power consumption, which allows wireless communication in the band below 1GHz.

The product is a radio solution for universal use created to work in the ISM bands (443, 868, 920 MHz). It is also possible to configure the transmitter so that it works on other frequencies in the bands 413 – 479 MHz and 826 – 958 MHz. S2-LPTX supports modulations such as: 2 (G) FSK, 4 (G) FSK, OOK and ASK, while the data transmission rate can be set in the range from 0.1 to 500 Kbps.


Applications for S2-LPTX: sensors to cloud, smart metering, home energy management systems, wireless alarm systems, smart home, building automation, industrial monitoring and control, smart lighting systems.

Dedicated products

The manufacturer has prepared a dedicated filter for the S2-LPTX transmitter – the ultra-miniature BALF-SPI2-01D3, which integrates a harmonic filter and impedance matching. BALF-SPI2-01D3 uses IPD technology (from STMicroelectronics) on a non-conductive glass substrate that optimizes the properties of the radio path.

Antennas – it’s good to use proven products

Matching proant-unictronMatching the right antenna to your wireless application is always a challenge for the designer. When creating an application based on the S2-LPTX transmitter, it is worth considering the use of antennas from Proant or Unictron. In particular, we recommend the PRO-OB-471 model from Proant (PIFA type antenna for the frequency range: 860MHz – 870MHz, 902MHz – 928MHz) and model AA701 from Unictron (ceramic antenna for the operating frequency range: 863 – 870 Mhz). The Proant PRO-OB-471 antenna shows very low sensitivity of radio parameters to metal elements located in close proximity to the antenna.

Recommended quartz and TCXO

For the application based on the S2-LPTX system, we propose small quartz for surface mounting, which are dedicated to this solution. The NDK product called NX3225GA has compact dimensions (3.2 × 2.5 × 0.75 mm) and high frequency stability. For applications that require a narrow radio channel and work in a wide temperature range, we recommend TCXO NT2016SA frpom NDK.

More information

We encourage you to contact us masters@masters.com.pl. We will present a detailed offer from choosing the right components, through comprehensive technical support to mass production.