آر اف (فرکانس رادیویی) و بی‌سیم آی سی‌ فرستنده‌گیرنده آر اف

Product Attributes

Introduction

Excellent selectivity: 58 dB adjacent channel, 75 dB blocking gain at 1 MHz; antenna diversity and T/R switch control; highly configurable packet handler; TX and RX 64-byte FIFO; automatic frequency control (AFC); automatic gain control (AGC); low BOM; low battery detector; temperature sensor; 20-pin QFN package; IEEE 802.15.4g ready; suitable for China regulatory compliance (State Grid).

High-performance, low-current transceiver covering the sub-GHz band from 425 to 525 MHz. Targeting the Chinese smart metering market, particularly well-suited for smart electricity meters. The device footprint and pinout are compatible with Si446x radios, delivering industry-leading performance for sub-GHz applications. Outstanding sensitivity of –124 dBm is achieved simultaneously with ultra-low active and standby current consumption. 12.5 kHz channel spacing with 58 dB adjacent channel selectivity ensures reliable reception under demanding RF conditions. Exceptional output power of up to +20 dBm with significant TX efficiency is available. The high output power and sensitivity yield an industry-leading 144 dB link budget, enabling extended range and highly reliable communication links.

The Si4438 is a high-performance, low-current wireless ISM transceiver covering the sub-GHz band. The wide operating voltage range of 1.8–3.8 V and low current consumption make the Si4438 ideal for battery-powered applications. The Si4438 operates as a TDD transceiver, alternately transmitting and receiving data packets. The device employs a single-conversion mixing architecture to down-convert received signals modulated with 2-level FSK/GFSK or OOK to a lower IF frequency. Following a programmable gain amplifier (PGA), the signal is converted to the digital domain via a high-performance ΔΣ ADC, enabling filtering, demodulation, despreading, and packet processing within the integrated DSP — enhancing receiver performance and flexibility compared to analog-based architectures. The demodulated signal can be output to an MCU system via programmable GPIO or through a standard SPI bus by reading the 64-byte RX FIFO.

Since the transmitter and receiver cannot operate simultaneously, a single high-precision local oscillator (LO) is shared between transmit and receive modes. The LO is synthesized using an integrated VCO and ΔΣ Fractional-N PLL synthesizer. The synthesizer supports configurable data rates from 100 bps to 500 kbps. Transmitted FSK data is directly modulated into the ΔΣ data stream and can be shaped by a Gaussian low-pass filter to reduce unwanted spectral content.

The Si4438 integrates a power amplifier (PA) capable of supporting output power up to +20 dBm at very high efficiency while consuming only 75 mA of current. The integrated +20 dBm PA can also be used to compensate for the performance loss of lower-cost, lower-performance antennas or size-constrained antennas limited by small form factors. Competing solutions require larger, more expensive external PAs to achieve comparable performance. The single-ended PA enables easy antenna matching and low BOM cost. The PA includes automatic ramp-up and ramp-down control to reduce unwanted spectral spreading. The Si4438 product family supports TX/RX switch control and antenna diversity switch control to extend link range and improve performance. Built-in antenna diversity can be used to further extend range and enhance performance. Antenna diversity is fully integrated into the Si4438 and can improve the system link budget by 8–10 dB, enabling significant range extension under adverse environmental conditions. The highly configurable packet handler enables autonomous encoding and decoding of virtually any packet structure. Additional system features such as an auto wake-up timer, low battery detector, 64-byte TX/RX FIFO, and preamble detection reduce overall current consumption and allow use of lower-cost system MCUs. An integrated temperature sensor, power-on reset (POR), and GPIO further reduce overall system cost and size. The Si4438 works together with an MCU, crystal, and a few passive components to create an extremely low-cost system.

Features

• Frequency range = 425 - 525 MHz
• Receive sensitivity = –124 dBm
• Modulation: (G)FSK, OOK
• Maximum output power: +20 dBm
• Low active current consumption: 14 mA RX
• Ultra-low current shutdown modes: 30 nA shutdown, 40 nA standby
• Data rate = 100 bps to 500 kbps
• Preamble detection mode: 6 mA average Rx at 1.2 kbps
• Fast wake-up and frequency hopping
• Supply voltage = 1.8 to 3.8 V

Applications

• China Smart Meter