EFR32BG1B232 Datasheet, PDF (10/163 Pages) Silicon Laboratories – EFR32BG1 Blue Gecko Bluetooth® Smart SoC Family Data Sheet

EFR32BG1 Blue Gecko Bluetooth® Smart SoC Family Data Sheet
System Overview
3.2.1 Antenna Interface
The EFR32BG1 family includes devices which support both single-band and dual-band RF communication over separate physical RF
interfaces.
The 2.4 GHz antenna interface consists of two pins (2G4RF_IOP and 2G4RF_ION) that interface directly to the on-chip BALUN. The
2G4RF_ION pin should be grounded externally.
The sub-GHz antenna interface consists of a differential transmit interface (pins SUBGRF_OP and SUBGRF_ON) and a differential re-
ceive interface (pinsSUBGRF_IP and SUBGRF_IN).
The external components and power supply connections for the antenna interface typical applications are shown in the RF Matching
Networks section.
3.2.2 Fractional-N Frequency Synthesizer
The EFR32BG1 contains a high performance, low phase noise, fully integrated fractional-N frequency synthesizer. The synthesizer is
used in receive mode to generate the LO frequency used by the down-conversion mixer. It is also used in transmit mode to directly
generate the modulated RF carrier.
The fractional-N architecture provides excellent phase noise performance combined with frequency resolution better than 100 Hz, with
low energy consumption. The synthesizer has fast frequency settling which allows very short receiver and transmitter wake up times to
optimize system energy consumption.
3.2.3 Receiver Architecture
The EFR32BG1 uses a low-IF receiver architecture, consisting of a Low-Noise Amplifier (LNA) followed by an I/Q down-conversion mix-
er, employing a crystal reference. The I/Q signals are further filtered and amplified before being sampled by the IF analog-to-digital
converter (IFADC).
The IF frequency is configurable from 150 kHz to 1371 kHz. The IF can further be configured for high-side or low-side injection, provid-
ing flexibility with respect to known interferers at the image frequency.
The Automatic Gain Control (AGC) module adjusts the receiver gain to optimize performance and avoid saturation for excellent selec-
tivity and blocking performance. The 2.4 GHz radio is calibrated at production to improve image rejection performance. The sub-GHz
radio can be calibrated on-demand by the user for the desired frequency band.
Demodulation is performed in the digital domain. The demodulator performs configurable decimation and channel filtering to allow re-
ceive bandwidths ranging from 0.1 to 2530 kHz. High carrier frequency and baud rate offsets are tolerated by active estimation and
compensation. Advanced features supporting high quality communication under adverse conditions include forward error correction by
block and convolutional coding as well as Direct Sequence Spread Spectrum (DSSS).
A Received Signal Strength Indicator (RSSI) is available for signal quality metrics, for level-based proximity detection, and for RF chan-
nel access by Collision Avoidance (CA) or Listen Before Talk (LBT) algorithms. An RSSI capture value is associated with each received
frame and the dynamic RSSI measurement can be monitored throughout reception.
The EFR32BG1 features integrated support for antenna diversity to improve link budget for 802.15.4 DSSS-OQPSK PHY configuration
in the 2.4GHz band, using complementary control outputs to an external switch. Internal configurable hardware controls automatic
switching between antennae during RF receive detection operations.
3.2.4 Transmitter Architecture
The EFR32BG1 uses a direct-conversion transmitter architecture. For constant envelope modulation formats, the modulator controls
phase and frequency modulation in the frequency synthesizer. Transmit symbols or chips are optionally shaped by a digital shaping
filter. The shaping filter is fully configurable, including the BT product, and can be used to implement Gaussian or Raised Cosine shap-
ing.
Carrier Sense Multiple Access - Collision Avoidance (CSMA-CA) or Listen Before Talk (LBT) algorithms can be automatically timed by
the EFR32BG1. These algorithms are typically defined by regulatory standards to improve inter-operability in a given bandwidth be-
tween devices that otherwise lack synchronized RF channel access.
3.2.5 Wake on Radio
The Wake on Radio feature allows flexible, autonomous RF sensing, qualification, and demodulation without required MCU activity, us-
ing a subsystem of the EFR32BG1 including the Radio Controller (RAC), Peripheral Reflex System (PRS), and Low Energy peripherals.
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