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SmartRF CC400 / CC900

SmartRF CC400 / CC900. Single Chip High Performance RF Transceivers. Peder Martin Evjen, M.Sc.E.E Field Application Engineer. Applications overview. UHF wireless FSK data transmitters and receivers LPD, Low Power Devices SRD, Short Range Devices ISM, Industrial - Scientific - Medicine

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SmartRF CC400 / CC900

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  1. SmartRFCC400 / CC900 Single Chip High Performance RF Transceivers Peder Martin Evjen, M.Sc.E.E Field Application Engineer

  2. Applications overview • UHF wireless FSK data transmitters and receivers • LPD, Low Power Devices • SRD, Short Range Devices • ISM, Industrial - Scientific - Medicine • 433 and 418 MHz SRD band systems • 868MHz European SRD band • 260 - 470 US ISM band • 902-928 US ISM band

  3. Applications overview • Keyless entry with acknowledgement • Telemetry / remote metering of; • electricity, water, gas • temperature, pressure • environment and air quality • Smart House applications • lights, heat, alarms, comfort, electrical equipment • Alarm and security systems • Remote Tagging (RF Tag) • Industrial Remote Controls • lifts, cranes, industrial equipment • “Intelligent” toys

  4. Radio transmission system • CC400/900: One-chip RF transceiver • FSK modulation (superior to ASK) • Up to 9.6kbps (19.2kbaud) Data source Micro controller RF transceiver (De)coding Manchester (De)modulation FSK NRZ

  5. CC400/CC900RF transceiver • Three-wire control interface • Data in/out (bi-directional) • RF antenna in/out DIO RF PDATA CLOCK STROBE

  6. Block diagram

  7. Receiver features • Low noise front end (3dB noise figure) • High sensitivity CC400: -112dBm @ 1.2kbps,BER=10-3CC900: -110dBm @ 1.2kbps,BER=10-3 • Fully integrated IF stage, no external filters needed (optional ext. 455kHz) • Selectable IF frequency (60/200/455kHz) • Fully integrated FSK demodulator, no external ceramic resonator needed • Data rate 0.3 - 9.6 kbps

  8. Transmitter features • Integrated power amplifier - CC400: -5 to 14dBm (25mW)- CC900: -20 to 4dBm (2.5mW) • Programmable output power in 1dB steps • Fully integrated FSK modulator with programmable deviation (1-50 kHz) • Internal RX/TX switch

  9. Synthesiser features • Cover 300-500 MHz (CC400) 800-1000 MHz (CC900) • Very fine frequency resolution: • CC400: 5 kHz, CC900: 250 Hz • Free choice crystal frequency (4-13 MHz) • External loop filter for flexibility (optimise to data-rate) • External VCO tank for flexibility • PLL lock signal

  10. Chip features • Small package SSOP-28 • Low supply voltage (2.7-3.3 V) • Very low power-down/standby current typical 0.2 A • Few external components • Easy to use 3-wire control bus for configuration

  11. Radio range • CC400: >2000 m • CC900: >500 m • 10dBm, quarter wave antenna, 1.2kbps • Key issues: • Sensitivity • Output power • Antenna solution • Interferers / noise • 6dB ~ twice the distance

  12. Data interface - DIO pin • Bi-directional data pin (TX:in, RX:out) • Manchester code (a.k.a. bi-phase-level coding) - no DC component - timing information • Final data decision by micro-controller - code available

  13. Transmit operation • FSK modulation Frequency separation = 2 x df Fc-df fc Fc+df frequency DIO=low DIO=high

  14. Receive operation Frequency separation = 2 x df Frequency deviation = df • Mixing and FSK demodulation Intermediate frequency Freq. IF-df IF IF+df LO Fc-df fc Fc+df DIO=low DIO=high

  15. Configuration • 3-wire serial bus for configuration • 8 control registers of 13 bits each • 3 bit address • Totally 16bits x 8registers = 128 bits • Full configuration in 64 s (at 2MHz) • Configuration data generated by SmartRF Studio (software) -no bit trixing

  16. How to generate the configuration data • SmartRF Studio makes it easy: • Enter system parameters - carrier frequency - frequency seperation - IF frequency etc. • ‘File’ - ‘Print registers to file’ • A file containing all necessary configuration data is generated

  17. Print-out example RX Precharge mode: Frame Data (hex) 000 002A 001 030B 002 0141 003 051F 004 0A00 005 1A03 006 0B6C 007 0248 PD osc. on mode: Frame Data (hex) 000 102A 001 030B 002 0141 003 051F 004 0A00 005 1A03 006 0B6C 007 0040 PD osc. off mode: Frame Data (hex) 000 102A 001 030B 002 0151 003 051F 004 0A00 005 1A03 006 0B6C 007 0040 RX mode: Frame Data (hex) 000 002A 001 030B 002 0141 003 051F 004 0A00 005 1A03 006 0B6C 007 0040 TX mode: Frame Data (hex) 000 082A 001 030B 002 0141 003 0457 004 0A0A 005 1A03 006 0B6C 007 0040

  18. 3-wire serial interface • Up to 2MHz clock frequency • 3 bit register address sent first • MSB of data sent first

  19. Wiring up the circuit, CC400

  20. Wiring up the circuit, CC900

  21. External components • Crystal (tolerance, drift, ageing, load) • Input/output matching network- see SmartRF Studio • PLL loop filter (data rate)- see SmartRF Studio • VCO (voltage controlled oscillator) tank • Inductor Q, varactor tuning range • De-coupling and power filtering

  22. Optional components • External 455kHz ceramic IF filter • RF filter - LC filter (ref. data sheet)- SAW filter

  23. Critical components • VCO inductor should be “good Q” • Murata LQN21A or Coilcraft HQ-series • VCO capacitors tolerance • Varactor sensitivity and Q • Crystal tolerance, drift and ageing

  24. Crystal oscillator • RF frequency accuracy ~ crystal accuracy • Crystal specification: • Crystal tolerance • Crystal temperature drift (temp. range) • Crystal pulling (loading sensitivity) • Crystal load capacitance

  25. Crystal load capacitance • Total capacitance seen from crystal Cparacitic C151 C161

  26. Temperature compensation • 25kHz spacing in 868MHz band require <2.5ppm frequency accuracy • Very fine step synthesiser: 250 Hz • Crystal temperature drift compensation • External temperature sensor (single wire chips available) • Crystal drift curve must be known • Alternative to TCXO that cost USD 3-5

  27. VCO tank tolerances • Resonate frequency ~ component tolerance • +/-5% tolerance ==> 10% tuning range Frequency Tuning range Tuning sensitivity Tuning voltage 0 1 2 3

  28. VCO tuning range and sensitivity • Tuning range: • CC400: 60 MHz (14% at 433 MHz) • CC900: 75 MHz (8.6% at 869 MHz) • Tuning sensitivity: • CC400: 20 MHz/V • CC900: 25 MHz/V • Range must account for tolerances • Sensitivity influence PLL loop gain

  29. C91 C93 C92 L91 VAR VCO tank • L91 set impedance level400MHz : 10nH, 900MHz: 3n3H • C91 set VCO gain • C92 set tuning sensitivity • C93 set absolute range • Bits C11:9 set VCO amplifier gain, 000=max, 111=min VCO in V_tune from loop filter

  30. IF bandwidth • 60 kHz IF: 40 kHz bandwidth • 200 kHz IF: 200 kHz bandwidth • 455 kHz IF: Depend on ceramic filter • Signal bandwidth (Carson’s rule): • 2 x frequency error (ppm) • Frequency seperation ( 2 x deviation) • 2 x bitrate (Manchester code)

  31. Sensitivity, data rate and IF • CC400 • 1.2kbps = -112dBm (60kHz IF, 20kHz separation) • 1.2kbps = -107dBm (200kHz IF, 20kHz separation) • 1.2kbps = -108dBm (455kHz external filter, 12kHz separation) • 9.6kbps = -105dBm (60kHz IF, 30kHz separation) • 9.6kbps = -102dBm (200kHz IF, 30kHz separation) • 9.6kbps = -96dBm (455kHz external filter, 20kHz separation)

  32. Sensitivity, data rate and IF • CC900 • 1.2kbps = -110dBm (60kHz IF, 20kHz separation) • 1.2kbps = -107dBm (200kHz IF, 20kHz separation)

  33. 25 kHz channel operation • EN 300220: ACP < -37dBm • Narrow loop filter • Low data rate (1.2kbps) • Low separation / deviation (2.5-10kHz) • Lower output power until requirement is met • Test receiver for measurements of ACP for correct bandwidth

  34. RX precharging • Use precharging to reduce receiver turn-on time (controls time-constant in demodulator data slicer) • Configure CC400/CC900 to RX with precharging • Wait for ca 5 bit periods • Configure CC400/CC900 to RX

  35. RX precharging

  36. Input/output match • See CC400DK user manual appendix • For CC900 the TX is not tuned (choke) • Antenna should be matched to 50 Ohm

  37. SAW filter • If SAW is used in both RX and TX the output power should not be >0dBm • Use external RX/TX switch and SAW only in RX path

  38. Increasing output power • CC900 has max 4dBm • Insert external amplifier (GaAs, SiGe) • GaAs / PIN diode switch • (insert SAW filter in receive path)

  39. Layout • Place VCO in distance from input/output match and XTAL • VCO tank with guard ring (possible to use shield) • No hole in the ground plane (not as in CC400DB) • Ground plane splitting depend on digital circuits around (Most cases a hole plane is preferred) • Two layer circuit board

  40. Antenna solutions • Single ended output makes it possible to use a wide range of antennas • Antennas integrated on the PCB • stubs • loops • PCB mounted antennas • helical • ceramic, “splatch” • External antennas • helical, short or full length monopole

  41. Feature - Benefit - Advantage

  42. Feature - Benefit - Advantage

  43. Technical support • FAE: Peder Martin Evjen • Address: Chipcon Components AS, Gaustadalléen 21, N-0349 OSLO, NORWAY • Phone: +47 22 95 83 01 • Fax: +47 22 95 85 46 • Web: http://www.chipcon.com • E-mail: p.m.evjen@chipcon.com

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