STM32WB50CG datasheet(18/119 Pages) STMICROELECTRONICS

18 / 119 page

Functional overview

STM32WB50CG STM32WB30CE

18/119

DS13047 Rev 5

Secure Firmware update (especially BLE or 802.15.4) from system boot and over the air is

provided.

3.6

RF subsystem

The STM32WB50CG and STM32WB30CE embed an ultra-low power multi-standard radio

Bluetooth® Low Energy (BLE) or 802.15.4 network processor, compliant with Bluetooth®

specification 5.2 and IEEE® 802.15.4-2011. The BLE features 1 Mbps transfer rate,

supports multiple roles simultaneously acting at the same time as BLE sensor and hub

device, embeds Elliptic Curve Diffie-Hellman (ECDH) key agreement protocol, thus

ensuring a secure connection.

The BLE stack or 802.15.4 Low Level layer run on an embedded Arm® Cortex®-M0+ core

(CPU2). The stack is stored on the embedded Flash memory, which is also shared with the

Arm® Cortex®-M4 (CPU1) application, making it possible in-field stack update.

3.6.1

RF front-end block diagram

The RF front-end is based on a direct modulation of the carrier in Tx, and uses a low IF

architecture in Rx mode.

Thanks to an internal transformer at RF pins, the circuit directly interfaces the antenna

(single ended connection, impedance close to 50 Ω). The natural bandpass behavior of the

internal transformer, simplifies outside circuitry aimed for harmonic filtering and out of band

interferer rejection.

In Transmit mode, the maximum output power is user selectable through the programmable

LDO voltage of the power amplifier. A linearized, smoothed analog control offers clean

power ramp-up.

In receive mode the circuit can be used in standard high performance or in reduced power

consumption (user programmable). The Automatic gain control (AGC) is able to reduce the

chain gain at both RF and IF locations, for optimized interference rejection. Thanks to the

use of complex filtering and highly accurate I/Q architecture, high sensitivity and excellent

linearity can be achieved.

The bill of material is reduced thanks to the high degree of integration. The radio frequency

source is synthesized form an external 32 MHz crystal that does not need any external

trimming capacitor network thanks to a dual network of user programmable integrated

capacitors.

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