IC. AD7021 Datasheet

AD7021 Datasheet PDF


AD7021
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Preliminary Technical Data
High Performance Narrowband
ISM Transceiver IC
ADF7021
FEATURES
Low power, low IF transceiver
Frequency bands
80 MHz to 650 MHz
862 MHz to 940 MHz
Modulation schemes
2FSK, 3FSK, 4FSK
Spectral shaping
Gaussian and raised-cosine filtering
Data rates supported
0.05 kbps to 25 kbps
2.3 V to 3.6 V power supply
Programmable output power
−16 dBm to +13 dBm in 63 steps
Automatic PA ramp control
Receiver sensitivity
−125 dBm at 1 kbps, 2 FSK
On-chip VCO and fractional-N PLL
RSET
On-chip 7-bit ADC and temperature sensor
Fully automatic frequency control loop (AFC)
Digital RSSI
Integrated Tx/Rx switch
Leakage current <1 μA in power-down mode
APPLICATIONS
Narrow-band standards
ETSI EN 300-220, FCC Part 90, FCC Part 15, FCC Part 95,
ARIB STD-T67
Low cost, wireless data transfer
Remote control/security systems
Wireless metering
Private mobile radio
Wireless medical telemetry service (WMTS)
Keyless entry
Home automation
Process and building control
Pagers
FUNCTIONAL BLOCK DIAGRAM
CE CREG(1:4)
MUXOUT
RLNA
POLARIZATION
TEMP
SENSOR
MUX
7-BIT ADC
LDO(1:4)
TEST MUX
RFIN
RFINB
LNA
GAIN
IF FILTER
RSSI/
OFFSET
CORRECTION
2FSK
3FSK
4FSK
DEMODULATOR
CLOCK
AND DATA
RECOVERY
Tx/Rx
CONTROL
PA RAMP
RFOUT
DIVIDERS/
MUXING
MUX
VCO
AGC
CONTROL
AFC
CONTROL
SERIAL
PORT
DIV P
N/N + 1
Σ-Δ
MODULATOR
2FSK
3FSK
4FSK
MOD CONTROL
CP PFD
DIV R
RING OSC
CLK
DIV
GAUSSIAN/
RAISED COSINE
FILTER
3FSK
ENCODING
L1 L2 VCOIN CPOUT
OSC1 OSC2
Figure 1.
CLKOUT
DATA CLK | TxDATA
DATA I/O | RxDATA
SWD
SLE
SDATA
SREAD
SCLK
Rev. PrI
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Part AD7021
Description High Performance Narrowband ISM Transceiver IC
Feature AD7021; www.DataSheet4U.com Preliminary Technical Data FEATURES Low power, low IF transceiver Frequency ban.
Manufacture Analog Devices
Datasheet
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AD7021
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ADF7021
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 3
Specifications..................................................................................... 4
Timing Characteristics..................................................................... 7
Absolute Maximum Ratings............................................................ 9
ESD Caution.................................................................................. 9
Pin Configuration and Function Descriptions........................... 10
Frequency Synthesizer ................................................................... 12
Reference Input........................................................................... 12
MUXOUT.................................................................................... 13
Voltage Controlled Oscillator (VCO) ...................................... 14
Choosing Channels for Best System Performance................. 14
Transmitter ...................................................................................... 15
RF Output Stage.......................................................................... 15
Modulation Schemes.................................................................. 15
Spectral Shaping ......................................................................... 17
Modulation and Filtering Options ........................................... 17
Receiver Section.............................................................................. 18
RF Front End............................................................................... 18
RSSI/AGC.................................................................................... 19
FSK Demodulators on the ADF7021....................................... 19
FSK Correlator/Demodulator................................................... 19
Linear 2FSK Demodulator ........................................................ 21
3FSK Demodulator..................................................................... 21
4FSK Demodulator..................................................................... 21
Preliminary Technical Data
AFC Section ................................................................................ 21
Automatic Sync Word Recognition ......................................... 22
Applications..................................................................................... 23
LNA/PA Matching...................................................................... 23
Transmit Protocol and Coding Considerations ..................... 24
Device Programming after Initial Power-Up ........................... 24
Interfacing to Microcontroller/DSP ........................................ 26
Serial Interface ................................................................................ 27
Readback Format........................................................................ 27
Register 0—N Register............................................................... 28
Register 1—VCO/Oscillator Register ...................................... 29
Register 2—Transmit Modulation Register ............................ 30
Register 3—Transmit/Receive Clock Register........................ 31
Register 4—Demodulator Setup Register ............................... 32
Register 5—IF Filter Setup Register......................................... 33
Register 6—IF Fine Cal Setup Register ................................... 34
Register 7—Readback Setup Register...................................... 35
Register 8—Power Down Test Register................................... 36
Register 9—AGC Register......................................................... 37
Register 10—AFC Register ....................................................... 38
Register 11—Sync Word Detect Register................................ 39
Register 12—SWD/Threshold Setup Register........................ 40
Register 13—3FSK Demod Register ........................................ 41
Register 14—Test-DAC Register .............................................. 41
Register 15—Test Mode Register ............................................. 42
Outline Dimensions ....................................................................... 44
Ordering Guide .......................................................................... 44
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AD7021
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Preliminary Technical Data
GENERAL DESCRIPTION
The ADF7021 is a low power, highly integrated 2FSK/3FSK/4FSK
transceiver. It is designed to operate in the narrow-band,
license-free ISM bands and licensed bands in the 80 MHz to
650 MHz and 862 MHz to 940 MHz frequency ranges. It has
both Gaussian and raised cosine data filtering options to
improve spectral efficiency for narrow-band applications.
It is suitable for circuit applications targeted at European
ETSI-EN 300-220, the Japanese ARIB STD-T67, the Chinese
Short Range Device regulations, and the North American FCC
Part 15, Part 90, and Part 95 regulatory standards. A complete
transceiver can be built using a small number of external
discrete components, making the ADF7021 very suitable for
price-sensitive and area-sensitive applications.
The transmit section contains a voltage controlled oscillator
(VCO) and a low noise fractional-N PLL with output resolution
of <1 ppm. This frequency-agile PLL allows the ADF7021 to be
used in frequency hopping spread spectrum (FHSS) systems.
The VCO operates at twice the fundamental frequency to
reduce spurious emissions and frequency pulling problems.
The transmitter output power is programmable in 63 steps from
−16 dBm to +13 dBm and has an automatic power ramp control
to prevent spectral splatter and help meet regulatory standards.
The transceiver RF frequency, channel spacing, and modulation
are programmable using a simple 3-wire interface. The device
operates with a power supply range of 2.3 V to 3.6 V and can be
powered down when not in use.
ADF7021
A low IF architecture is used in the receiver (100 kHz),
minimizing power consumption and the external component
count while avoiding interference problems at low frequencies.
The IF filter has programmable bandwidths of 12.5 kHz,
18.75 kHz, and 25 kHz. The ADF7021 supports a wide variety
of programmable features including Rx linearity, sensitivity, and
IF bandwidth, allowing the user to trade off receiver sensitivity
and selectivity against current consumption, depending on the
application. The receiver also features a patent-pending
automatic frequency control (AFC) loop with programmable
pull-in range, allowing the PLL to track out the frequency error
in the incoming signal.
An on-chip ADC provides readback of an integrated tempera-
ture sensor, an external analog input, the battery voltage, and
the RSSI signal, which provides savings on an ADC in some
applications. The temperature sensor is accurate to ±10°C over
the full operating temperature range of −40°C to +85°C. This
accuracy can be improved by doing a 1-point calibration at
room temperature and storing the result in memory.
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