MLX71122

300 to 930MHz FSK/FM/ASK Receiver

Datasheet

REVISION 014 – AUGUST, 2016

Page 3 of 59

390 10 71122 01

Document Content

1. Theory of Operation.........................................................................................................................6

1.1. General................................................................................................................................................... 6

1.2. Technical Data Overview ........................................................................................................................ 7

1.3. Block Diagram ........................................................................................................................................ 7

1.4. Enable/Disable in ABC Mode.................................................................................................................. 8

1.5. Demodulation Selection in ABC Mode ................................................................................................... 8

1.6. Programming Modes.............................................................................................................................. 8

1.7. Preconfigured Frequencies in ABC Mode .............................................................................................. 8

2. Pin Definitions and Descriptions ....................................................................................................10

2.1. Pin Schematics ..................................................................................................................................... 10

2.2. RF Pin Impedance Models.................................................................................................................... 15

3. Functional Description ...................................................................................................................16

3.1. Frequency Planning.............................................................................................................................. 16

3.1.1. Calculation of Counter Settings .................................................................................................... 18

3.1.2. Calculation of LO1 and IF1 frequency for Low Frequency Bands ................................................. 19

3.1.3. Calculation of LO1 and IF1 frequency for High Frequency Bands ................................................ 19

3.1.4. Counter Setting Examples for SPI Mode....................................................................................... 20

3.1.5. Counter Settings in ABC Mode – 8+1 Preconfigured Channels .................................................... 20

3.2. PLL Frequency Synthesizer................................................................................................................... 21

3.2.1. Pulse Swallow Counter ................................................................................................................. 22

3.2.2. PLL Counter Ranges ...................................................................................................................... 23

3.2.3. Reference Oscillator (RO) ............................................................................................................. 23

3.2.4. Phase-Frequency Detector (PFD) ................................................................................................. 24

3.2.5. Charge Pump (CP)......................................................................................................................... 24

3.2.6. Loop Filter (LF).............................................................................................................................. 24

3.2.7. Lock Detector (LD) ........................................................................................................................ 25

3.2.8. Voltage Controlled Oscillator (VCO) ............................................................................................. 26

3.2.9. Loop Filter Calculation .................................................................................................................. 26

3.3. Receiver Front End ............................................................................................................................... 28

3.3.1. Low Noise Amplifier (LNA) and Mixer 1 (MIX1)............................................................................ 28

3.3.2. Mixer 2 (MIX2).............................................................................................................................. 29

3.3.3. IF Filter (IFF).................................................................................................................................. 29

3.3.4. FSK Demodulator.......................................................................................................................... 30

3.3.5. Autotuning Circuit ........................................................................................................................ 30

3.3.6. IF Amplifier (IFA) ........................................................................................................................... 31

3.3.7. Automatic Gain Control (AGC)...................................................................................................... 32

3.4. Data Path.............................................................................................................................................. 33