TH71101 Datasheet, PDF (2/20 Pages) List of Unclassifed Manufacturers – FSK/FM/ASK Receiver

TH71101
315/433MHz
FSK/FM/ASK Receiver
General Description
The TH71101 receiver IC consists of the following building blocks
" PLL synthesizer (PLL SYNTH) for generation of the local oscillator signal LO
" Parts of the PLL SYNTH are the high-frequency VCO1, the feedback divider DIV_16,
a phase-frequency detector (PFD) with charge pump (CP) and a crystal-based reference oscillator (RO)
" Low-noise amplifier (LNA) for high-sensitivity RF signal reception
" First mixer (MIX1) for down-conversion of the RF signal to the IF
" IF pre amplifier which is a mixer cell (MIX2) that operates as an amplifier
" IF amplifier (IFA) to amplify and limit the IF signal and for RSSI generation
" Phase coincidence demodulator (DEMOD) with third mixer (MIX3) to demodulate the IF signal
" Operational amplifier (OA) for data slicing, filtering and ASK detection
" Bias circuitry for bandgap biasing and circuit shutdown
With the TH71101 receiver chip, various circuit configurations can be arranged in order to meet a number of
different customer requirements. For FM/FSK reception the IF tank used in the phase coincidence demodu-
lator can be constituted either by a ceramic resonator or an LC tank (optionally with a varactor diode to create
an AFC circuit). In ASK configuration, the RSSI signal is feed to an ASK detector, which is constituted by the
operational amplifier.
Demodulation
FM / FSK
FM / FSK
ASK
Type of receiver
narrow-band RX with ceramic demodulation tank
wide-band RX with LC demodulation tank
RX with RSSI-based demodulation
A double-conversion variant, called TH71102, is also available. This receiver IC allows a higher degree of
image rejection, achieved in conjunction with an RF frontend filter. Both RXICs have the same die. At the
TH71102, the second mixer (MIX2) is used to down-convert the first IF (IF1) to the second IF (IF2). At the
TH71101, MIX2 operates as an amplifier.
Efficient RF frontend filtering is realized by using a SAW, ceramic or helix filter in front of the LNA and by
adding an LC filter at the LNA output.
TH71101 Data Sheet
3901071101
Page 2 of 20
Nov. 2001
Rev. 005