Micrel MICRF506 Manual

General Description

The MICRF506 is a true single-chip, frequency shift keying
(FSK) transceiver intended for use in half-duplex,
bidirectional RF links. The multi-channeled FSK transceiver
is intended for UHF radio equipment in compliance with the
European Telecommunication Standard Institute (ETSI)
specification, EN300 220.
The transmitter consists of a PLL frequency synthesizer
and power amplifier. The frequency synthesizer consists of
a voltage-controlled oscillator (VCO), a crystal oscillator,
dual modulus prescaler, programmable frequency dividers,
and a phase-detector. The loop-filter is external for flexibility
and can be a simple passive circuit. The output power of
the power amplifier can be programmed to seven levels. A
lock-detect circuit detects when the PLL is in lock. In
receive mode, the PLL synthesizer generates the local
oscillator (LO) signal. The N, M, and A values that give the
LO frequency are stored in the N0, M0, and A0 registers.
The receiver is a zero intermediate frequency (IF) type
which makes channel filtering possible with low-power,
integrated low-pass filters. The receiver consists of a low
noise amplifier (LNA) that drives a quadrature mix pair. The
mixer outputs feed two identical signal channels in phase
quadrature. Each channel includes a pre-amplifier, a third
order Sallen-Key RC low-pass filter that protects the
following switched-capacitor filter from strong adjacent
channel signals, and a limiter. The main channel filter is a
switched-capacitor implementation of a six-pole elliptic low
pass filter. The cut-off frequency of the Sallen-Key RC filter
can be programmed to four different frequencies: 100kHz,
150kHz, 230kHz, and 340kHz. The I and Q channel
outputs are demodulated and produce a digital data output.
The demodulator detects the relative phase of the I and the
Q channel signal. If the I channel signal lags behind the Q
channel, the FSK tone frequency is above the LO
frequency (data '1'). If the I channel leads the Q channel,
the FSK tone is below the LO frequency (data '0'). The
output of the receiver is available on the DataIXO pin. A
receive signal strength indicator (RSSI) circuit indicates the
received signal level. All support documentation can be
found on Micrel's web site at www.micrel.com.
July 2006
MICRF506
410MHz and 450MHz ISM Band
Transceiver

Features

• True single chip transceiver
• Digital bit synchronizer
• Received signal strength indicator (RSSI)
• RX and TX power management
• Power down function
• Reference crystal tuning capabilities
• Frequency error estimator
• Baseband shaping
• Three-wire programmable serial interface
• Register read back function

Applications

• Telemetry
• Remote metering
• Wireless controller
• Remote data repeater
• Remote control systems
• Wireless modem
• Wireless security system
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