ADF7020BCPZ Analog Devices Inc, ADF7020BCPZ Datasheet - Page 26

• Manufacturer Part Number: ADF7020BCPZ
• Description: IC TX FSK/ASK ISM BAND 48LFCSP
• Manufacturer: Analog Devices Inc

Specifications of ADF7020BCPZ

• Design Resources: Low power, Long Range, ISM Wireless Measuring Node (CN0164)
• Frequency: 431MHz ~ 478MHz and 862MHz ~ 956MHz
• Data Rate - Maximum: 200kbps
• Modulation Or Protocol: ASK, FSK
• Applications: Data Transfer, RKE, Remote Control/Security Systems
• Power - Output: -16dBm ~ 13dBm
• Sensitivity: -119dBm
• Voltage - Supply: 2.3 V ~ 3.6 V
• Current - Receiving: 19mA
• Current - Transmitting: 26.8mA @ 10dBm
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-LFCSP
• Data Rate: 200Kbps
• Supply Voltage Range: 2.3V To 3.6V
• Logic Case Style: LFCSP
• No. Of Pins: 48
• Operating Temperature Range: -40°C To +85°C
• Msl: MSL 1 - Unlimited
• Termination Type: SMD
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 7mm
• Product Length (mm): 7mm
• Operating Supply Voltage (min): 2.3V
• Operating Supply Voltage (typ): 2.5/3.3V
• Operating Supply Voltage (max): 3.6V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADF7020DBZ3 - BOARD EVAL ADF7020 433-445MHZEVAL-ADF7020DBZ2 - BOARD EVAL ADF7020 862-870MHZEVAL-ADF7020DBZ1 - BOARD EVAL ADF7020 902-928MHZ
• Memory Size: -
• Lead Free Status / Rohs Status: Compliant

ADF7020
The procedure typically requires several iterations until an
acceptable compromise is reached. The successful implementation
of a combined LNA/PA matching network for the ADF7020 is
critically dependent on the availability of an accurate electrical
model for the PC board. In this context, the use of a suitable
CAD package is strongly recommended. To avoid this effort,
however, a small form-factor reference design for the ADF7020
is provided, including matching and harmonic filter components.
Gerber files and schematics are available at www.analog.com.
IMAGE REJECTION CALIBRATION
The image channel in the ADF7020 is 400 kHz below the
desired signal. The polyphase filter rejects this image with an
asymmetric frequency response. The image rejection
performance of the receiver is dependent on how well matched
the I and Q signals are in amplitude, and how well matched the
quadrature is between them (that is, how close to 90º apart they
are.) The uncalibrated image rejection performance is
approximately 30 dB. However, it is possible to improve this
performance by as much as 20 dB by finding the optimum I/Q
gain and phase adjust settings.
EXTERNAL
SOURCE
SIGNAL
Figure 34. Image Rejection Calibration Using the Internal Calibration Source and a Microcontroller
MATCHING
RFINB
RFIN
LNA
Rev. B | Page 26 of 48
PHASE ADJUSTMENT
MICROCONTROLLER
I
FROM LO
PHASE ADJUST
GAIN ADJUST
REGISTER 10
REGISTER 10
Calibration Procedure and Setup
The image rejection calibration works by connecting an
external RF signal to the RF input port. The external RF signal
should be set at the image frequency and the filter rejection
measured by monitoring the digital RSSI readback. As the
image rejection is improved by adjusting the I/Q Gain and
phase, the RSSI reading reduces.
The magnitude of the phase adjust is set by using the IR_PHASE_
ADJUST bits (R10_DB[24:27]). This correction can be applied
to either the I channel or Q channel, by toggling bit (R10_DB28).
The magnitude of the I/Q gain is adjusted by the IR_GAIN_
ADJUST bits (R10_DB[16:20]). This correction can be applied
to either the I or Q channel using bit (R10_DB22), while the
GAIN/ATTENUATE bit (R10_DB21) sets whether the gain
adjustment defines a gain or attenuation adjust.
The calibration results are valid over changes in the ADF7020
supply voltage. However, there is some variation with temperature.
A typical plot of variation in image rejection over temperature
after initial calibrations at +25°C, −40°C, and +85°C is shown in
Figure 35. The internal temperature sensor on the ADF7020 can
be used to determine if a new IR calibration is required.
I/Q GAIN/PHASE ADJUST AND
Q
RSSI MEASUREMENT
ALGORITHM
INTERFACE
SERIAL
POLYPHASE
IF FILTER
4
4
RSSI READBACK
7-BIT ADC
LOG AMP
RSSI/
ADF7020