RFM219SW

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5. Functional Descriptions

RFIN

GND

LNA

I-MXR

Q-MXR

Image

Rejection

Band-pass

Filter

I-LMT

RSSI

Q-LMT

SAR

AGC

DEMOD

AFC & AGC

Radio

Controller

4-wire SPI,

FIFO

Interface

FCSB

CSB

SCL

SDA

VDD

LO GEN

LDOs

Bandgap

VCO

Loop

Filter

Divider

PFD/CP

26 MHz

EEPROM

LPOSC

IO Control

GPO1

GPO2

GPO3

GND

POR

AFC & Σ-Δ Modulator

XOSC

GPO4

VCON

VCOP

XIN

XOUT

Figure 10. Functional Block Diagram

5.1 Overview

The RFM219SW is an ultra low power, high performance, OOK and (G)FSK RF receiver for various 300 to 960 MHz wireless

applications. It is part of the HOPERF NextGenRF

transceivers. The device is based on a fully integrated, low-IF receiver architecture. The low-IF architecture facilitates a very low

external component count and does not suffer from powerline - induced interference problems. The RF signal coming from

antenna is amplified, down-converted, filtered and further amplified in analog domain before sending into the digital demodulator.

The synthesizer contains a VCO and a low noise fractional-N PLL with an output frequency resolution of 24.8 Hz. The VCO

operates at 2x the Local Oscillator (LO) frequency to reduce spurious emissions. Every analog block is calibrated on each

Power-on Reset (POR) to the internal reference voltage. The calibration helps the device to finely work under different

temperatures and supply voltages. The baseband filtering and demodulation is done by the digital demodulator. The device

supports packet handling, 32-byte FIFO, Manchester decoding and data de-whitening for the received data processing. Besides

the demodulated data and the sync clock, the device can also send out the power-on reset, the system clock, as well as 2

configurable interrupts for the external device.

The 4-wire SPI interface is not only used for configuring the device by programming the EEPROM, but also controlling the device

by the external MCU. All features can be configured either by off-line EEPROM programming or on-line registers writing. The

configuration file to be written into the registers is generated by the smart RFPDK. The RF Frequency, symbol rate and other

product features are all configurable. This saves the cost and simplifies the design, development and manufacture. The

RFM219SW operates from 1.8 to 3.6 V so that it can finely work with most batteries to their useful power limits. The receive

sleep current for superior battery life. The RFM219SW receiver together with the CMT2119A transmitter enables a powerful RF

link.

5.2 Modulation, Frequency and Symbol Rate

The RFM219SW supports OOK demodulation with the symbol rate from 0.1 to 40 ksps and (G)FSK demodulation with the

symbol rate from 0.1 to 100 ksps. It continuously covers the frequency range from 300 to 960 MHz, including the license free

ISM frequency band around 315 MHz, 433.92 MHz, 868.35 MHz and 915 MHz. The internal frequency synthesizer contains a