RFRXD0420 Datasheet, PDF (2/32 Pages) Microchip Technology – UHF ASK/FSK/FM Receiver

rfRXD0420/0920
1.0 DEVICE OVERVIEW
The rfRXD0420/0920 are low cost, compact single
frequency short-range radio receivers requiring only a
minimum number of external components for a
complete receiver system. The rfRXD0420 covers the
receive frequency range of 300 MHz to 450 MHz and
the rfRXD0920 covers 800 MHz to 930 MHz. The
rfRXD0420 and rfRXD0920 share a common architec-
ture. They can be configured for Amplitude Shift Keying
(ASK), Frequency Shift Keying (FSK), or FM modula-
tion. The rfRXD0420/0920 are compatible with rfPIC™
and rfHCS series of RF transmitters.
• High frequency stability over temperature and
power supply variations
• Low spurious signal emission
• High large-signal handling capability with
selectable LNA gain control for improved dynamic
range
• Selectable IF bandwidth via external low cost
ceramic IF filter. The IF Frequency range is
selectable between 455 kHz to 21.4 MHz. This
facilitates the use of readily available low cost
10.7 MHz ceramic IF filters in a variety of
bandwidths.
• ASK or FSK for digital data reception
• FM modulation for analog signal reception
• FSK/FM demodulation using quadrature detector
(phase coincidence detector)
• Received Signal Strength Indication (RSSI) for
signal strength indication and ASK detection
• Wide supply voltage range
• Low active current consumption
• Very low standby current
The rfRXD0420/0920 is a single conversion superhet-
erodyne architecture. A block diagram is illustrated in
Figure 1-1. The rfRXD0420/0920 consists of:
• Low-noise amplifier (LNA) - Gain selectable
• Mixer for down-conversion of the RF signal to the
Intermediate Frequency (IF) followed by an IF
preamplifier
• Fully integrated Phase-Locked Loop (PLL)
frequency synthesizer for generation of the Local
Oscillator (LO) signal. The frequency synthesizer
consists of:
- Crystal oscillator
- Phase-frequency detector and charge pump
- High-frequency Voltage Controlled Oscillator
(VCO)
- Fixed feedback divider
- rfRXD0420 = divide by 16
- rfRXD0920 = divide by 32
• IF limiting amplifier to amplify and limit the IF
signal and for Received Signal Strength Indication
(RSSI) generation
• Demodulator (DEMOD) section consists of a
phase detector (MIXER2) and amplifier creating a
quadrature detector (also known as a phase
coincidence detector) to demodulate the IF signal
in FSK and FM modulation applications
• Operational amplifier (OPA) that can be config-
ured as a comparator for ASK or FSK data
decision or as a filter for FM modulation.
• Bias circuitry for bandgap biasing and circuit
shutdown
DS70090A-page 2
Preliminary
 2003 Microchip Technology Inc.