th71111 Melexis Company, th71111 Datasheet - Page 3

• Manufacturer Part Number: th71111
• Description: Receiver - 868/915mhz Fsk/ask, Single-conversion Superhet Lqfp32
• Manufacturer: Melexis Company

1
1.1
With the TH71111 receiver chip, various circuit configurations can be arranged in order to meet a number of
different customer requirements. For FSK reception the IF tank used in the phase coincidence demodulator
can be constituted by an external ceramic discriminator. In ASK configuration, the RSSI signal is fed to an
ASK detector, which is constituted by the operational amplifier.
A double-conversion variant, called TH71112, is also available. This receiver IC allows a higher degree of
image rejection, achieved in conjunction with an RF front-end filter. Both RXICs have the same die. At the
TH71112, the second mixer (MIX2) is used to down-convert the first IF (IF1) to the second IF (IF2). At the
TH71111, MIX2 operates as an amplifier.
Efficient RF front-end 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.
The TH71111 receiver IC consists of the following building blocks:
1.2
1) at 4 kbps NRZ, BER = 3⋅10
2) at 4 kbps NRZ, BER = 3⋅10
39010 71111
Rev. 014
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_32, 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
Input frequency range: 800 MHz to 930 MHz
Power supply range: 2.3 V to 5.5 V @ ASK
Temperature range: -40 °C to +85 °C
Standby current: 50 nA
Operating current: 7.5 mA @ low gain mode
Sensitivity: -112 dBm @ ASK 1)
Maximum data rate: 260 kbps NRZ @ ASK
Theory of Operation
General
Technical Data Overview
-106 dBm @ FSK 2)
9.2 mA @ high gain mode
180 kbps NRZ @ FSK
-3
-3
, ± 20 kHz FSK deviation, 180 kHz IF filter BW, without SAW front-end-filter loss
, 180 kHz IF filter BW, without SAW front-end-filter loss
Page 3 of 22
Range of IF: 400 kHz to 22 MHz
Maximum input level: -10 dBm @ ASK
Image rejection: > 45 dB (e.g. with 868.3 MHz
SAW front-end filter and at 10.7 MHz IF)
Spurious emission: < -70 dBm
Input frequency acceptance range: up to ±100 kHz
RSSI range: 70 dB
FSK deviation range: ±2.5 kHz to ±80 kHz
FSK/ASK Receiver
0 dBm @ FSK
TH71111
868/915MHz
Data Sheet
April/08