Oscillators And Clocks; Rf Frequency Synthesizer; Modulation Modes - Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual

2.4 Oscillators and Clocks

EFR32 has six different oscillators integrated, as shown in
Oscillator Frequency
HFXO 38 MHz - 40 MHz
HFRCO 1 MHz - 38 MHz
AUXHFRCO 1 MHz - 38 MHz
LFRCO 32768 Hz
LFXO 32768 Hz
ULFRCO 1000 Hz
The RC oscillators can be calibrated against either of the crystal oscillators in order to compensate for temperature and voltage supply
variations. Hardware support is included to measure the frequency of various oscillators against each other.
Oscillator and clock management is available through the Clock Management Unit (CMU), see section
Unit for details.

2.5 RF Frequency Synthesizer

The Fractional-N RF Frequency Synthesizer (SYNTH) provides a low phase noise LO signal to be used in both receive and transmit
modes.
The capabilities of the SYNTH include:
• High performance, low phase noise
• Fast frequency settling
• Fast and fully automated calibration
• Sub 100 Hz frequency resolution across the supported frequency bands

2.6 Modulation Modes

EFR32 supports a wide range of modulation modes in transmit and receive:
• 2-FSK, 2-GFSK, 4-FSK, 4-GFSK, MSK, GMSK, O-QPSK with half-sine shaping, ASK / OOK, DBPSK TX
• NRZ or Manchester support
• UART mode over air for legacy protocols
• Data rates ranging from 600 bps up to 2 Mbps
• Configurable frequency deviation
• Configurable Direct Sequence Spread Spectrum (DSSS), with spread sequences up to 32 chips encoding up to 4 information bits
• Configurable 4-FSK symbol encoding
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Table 2.1 EFR32 Oscillators on page
Table 2.1. EFR32 Oscillators
Optional? External
components
No Crystal
No -
No -
No -
Yes Crystal
No -
32.
Description
High accuracy, low jitter high frequency crystal oscillator. Tun-
able crystal loading capacitors are fully integrated. The HFXO
is required for all types of RF communication to be active.
Medium accuracy RC oscillator, typically used for timing dur-
ing startup of the HFXO and as a clock source as long as no
RF communication is active.
Medium accuracy RC oscillator, typically used as alternative
clock source for Analog to Digital Converter or Debug Trace.
Medium accuracy frequency reference typically used for medi-
um accuracy RTCC timing.
High accuracy frequency reference typically used for high ac-
curacy RTCC timing. Tunable crystal loading capacitors are
fully integrated.
Ultra low frequency oscillator typically used for the watchdog
timer.
Reference Manual
System Overview
11. CMU - Clock Management
Rev. 1.1 | 32