ADF7021 High Performance Narrowband ISM Transceiver


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To introduce ADF7021 ISM transceiver, its features and internal operations

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ADF7021 High Performance Narrowband ISM Transceiver

  1. 1. ADF7021 High Performance Narrowband ISM Transceiver <ul><li>Source: Analog Devices </li></ul>
  2. 2. Introduction <ul><li>Purpose </li></ul><ul><ul><li>To introduce ADF7021 ISM transceiver, its features and internal operations. </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>SDR communication </li></ul></ul><ul><ul><li>ADF7021 Overview </li></ul></ul><ul><ul><li>Block diagram and internal operations </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>16 pages </li></ul></ul>
  3. 3. Short Range Wireless Devices <ul><li>Short Range Device (SRD) covers radio transmitters which provide either unidirectional or bi-directional communication and which have a low capability of causing interference to other radio equipment. </li></ul><ul><li>The applications include: </li></ul><ul><ul><li>Automatic Meter Reading [AMI / AMR Smart Grid applications] </li></ul></ul><ul><ul><li>Telecontrol for Home/Building Automation Systems </li></ul></ul><ul><ul><li>Automotives, including Remote Keyless Entry & Remote Car Start Applications </li></ul></ul><ul><ul><li>Wireless Sensor Applications </li></ul></ul><ul><ul><li>Medical Telemetry </li></ul></ul><ul><ul><li>Alarms </li></ul></ul>Worldwide Sub-GHz Bands
  4. 4. Narrowband Communications <ul><li>A narrowband channel is generally defined as a channel bandwidth less than or equal to 25 kHz. </li></ul><ul><li>Transmitter Specifications </li></ul><ul><ul><li>Adjacent Channel Power (ACP): the amount of spectral energy leaking into adjacent channels </li></ul></ul><ul><ul><li>Frequency Drift: the amount the transmitter will drift from its nominal operating frequency under extreme test or operating conditions (voltage and temperature) </li></ul></ul><ul><ul><li>Spurious Emissions: emissions at frequencies other than those of the wanted carrier frequency and its sidebands </li></ul></ul><ul><li>Receiver Specifications </li></ul><ul><ul><li>Adjacent Channel Rejection (ACR): the ability of the receiver to reject an interferer located in an adjacent channel </li></ul></ul><ul><ul><li>Blocking: the ability of the receiver to reject out of band interferers (usually at 1- 10 MHz) </li></ul></ul>
  5. 5. ADF7021 Narrowband Solution <ul><li>Low power, high performance, narrowband transceiver </li></ul><ul><li>Frequency Bands: 80-650MHz and 862-940MHz </li></ul><ul><li>Modulation schemes: 2FSK, 3FSK, 4FSK </li></ul><ul><li>Spectral shaping: Gaussian and Raised Cosine Filtering </li></ul><ul><li>Data rates supported: 0.05kps to 25kbps </li></ul><ul><li>Programmable output power: -16dBm to +13dBm in 63 steps </li></ul><ul><li>Receiver sensitivity: -123dBm @ 1kbps FSK </li></ul><ul><li>Low IF architecture with programmable IF bandwidths of 12.5/18.5/25kHz </li></ul><ul><li>Other features: PA ramp, AFC, URAT interface </li></ul>
  6. 6. Block Diagram
  7. 7. Receiver Front End The differential inputs achieve a high level of resilience against spurious reception The quadrature downconversion mixer converts the RF signal to the IF frequency of 100 kHz.
  8. 8. Demodulation and Detection <ul><li>The quadrature outputs of the IF filter are first limited and then fed to a digital frequency correlator that performs filtering and frequency discrimination of the 2FSK/3FSK/4FSK spectrum. </li></ul><ul><li>A linear demodulator provides an output signal that is linearly proportional to the frequency of the limiter outputs. </li></ul><ul><li>A second-order, digital low-pass filter removes excess noise from the demodulated bit stream at the output of the discriminator. </li></ul><ul><li>Threshold/slicer detection is used for data recovery of 2FSK and 4FSK. </li></ul><ul><li>Data recovery of 3FSK can be implemented using either threshold detection or Viterbi detection. </li></ul>
  9. 9. Clock and Data Recovery <ul><li>The data rate tolerance of the CDR is dependent on the number of bit transitions in the transmit bit stream. </li></ul><ul><li>This tolerance is maximized, and the CDR lock time is minimized when a maximum transition bit pattern is used as a preamble. </li></ul><ul><li>it is advisable to use some form of data encoding to minimize the RLL, which allows the CDR circuit to successfully track the incoming data. </li></ul>
  10. 10. Automatic Frequency Control (AFC) Operation <ul><li>External AFC </li></ul><ul><ul><li>The user reads back the frequency information through the ADF7021 serial port and applies a frequency correction value to the fractional-N synthesizer-N divider. </li></ul></ul><ul><li>Internal AFC </li></ul><ul><ul><li>An internal control loop automatically monitors the frequency error and adjusts the synthesizer-N divider using an internal proportional integral (PI) control loop. </li></ul></ul><ul><li>The adjacent channel rejection (ACR) performance of the receivers can be degraded when AFC is enabled and the AFC correction range is close to the IF filter bandwidth. </li></ul><ul><li>When AFC errors are removed using either the internal or external AFC, further improvement in receiver sensitivity can be obtained by reducing the IF filter bandwidth. </li></ul>
  11. 11. Transmitter Output Power <ul><li>The power amplifier (PA) output current and the output power are programmable over a wide range. </li></ul><ul><li>The output power is set using R2_DB[13:18]. </li></ul><ul><li>The PA_BIAS bits (R2_DB[11:12]) facilitate an adjustment of the PA bias current to further extend the output power control range </li></ul>Setting output power
  12. 12. Transmitter Modulation <ul><li>2FSK </li></ul><ul><ul><li>Two-level frequency shift keying is implemented by setting the N value for the center frequency and then toggling it with the TxDATA line. </li></ul></ul><ul><li>3FSK </li></ul><ul><ul><li>In 3-level FSK modulation, the binary data (Logic 0 and Logic 1) is mapped onto three distinct frequencies. </li></ul></ul><ul><ul><li>Bit-to-symbol mapping for 3FSK is implemented using a linear convolutional encoder. </li></ul></ul><ul><li>4FSK </li></ul><ul><ul><li>In 4FSK modulation, two bits per symbol spectral efficiency is realized by mapping consecutive input bit-pairs in the Tx data bit stream to one of four possible symbols. </li></ul></ul>
  13. 13. Matching RF Input and Output Internal Rx/Tx Switch External Rx/Tx Switch
  14. 14. Serial Interface <ul><li>The serial interface allows the user to program the 16-/32-bit registers using a 3-wire interface (SCLK, SDATA, and SLE). </li></ul><ul><li>The serial interface operates from a regulator supply. </li></ul><ul><li>Data is clocked into the register, MSB first, on the rising edge of each clock (SCLK). </li></ul>
  15. 15. Interfacing To Microcontroller <ul><li>UART Mode </li></ul><ul><ul><li>TxRxCLK pin is configured to input transmit data in transmit mode. </li></ul></ul><ul><ul><li>TxRxDATA pin is configured to output receive data in receive mode. </li></ul></ul><ul><li>SPI Mode </li></ul><ul><ul><li>TxRxCLK pin is configured to input transmit data in transmit mode. </li></ul></ul><ul><ul><li>TxRxDATA pin is configured to output receive data in receive mode. </li></ul></ul><ul><ul><li>The data clock in both transmit and receive modes is available on the CLKOUT pin. </li></ul></ul>UART Mode SPI Mode
  16. 16. Additional Resource <ul><li>For ordering ADF7021 transceiver, please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li> </li></ul></ul><ul><li>For additional inquires contact our technical service hotline or even use our “Live Technical Chat” online facility </li></ul>