Mid-Semester Design Review High Frequency Radio with BPSK Modulation

2 Goal Statement Our project is to design and build a wireless 900 MHz transmitter and receiver for Simply Test, LLC. The transceiver is to conform as closely as possible to the IEEE a standards for Low Rate, Wireless Personal Area Networks (LR-WPAN) and utilize Binary Phase Shift Key (BPSK) modulation.

3 Deliverables Working transceiver prototype Sub-circuit designs for amplifiers and filter Simulations of sub-circuit designs in PSpice

4 Functional Requirements Transmit and receive binary data High carrier frequency Low power signal transmission Efficient high frequency PCB layout Conforms to IEEE a standards for wireless LANs Transmission range for a conventional wireless network

5 Specifications Transmission range of 20 – 30 meters Antenna and transmission power of 12 dBm MHz carrier frequency Data throughput of 40kbps

6 System Block Diagram

7 Analysis Breakdown Transmitter  Mixer/Modulation  Power Amplifier Antennas Receiver  LNA  Filter  IF Amplifier  Demodulator

8 Mixer/Modulation Translation between a high frequency (the RF) and Intermediate Frequency (IF) The signal is imposed onto a carrier signal so that transmission circuits can be realized on a practical scale The modulation scheme defines how the signal is imposed onto the carrier signal for transmission

9 BPSK Modulation BPSK = Binary Phase Shift Key Binary 1 represented by 180° phase shift in carrier signal Binary 0 has no phase shift

10 Diode Mixers Provide a simpler topology compared to transistor based mixers Have a lower noise figure compared to transistor based mixers Have a higher conversion loss than transistor based mixers Excellent Poor4 Double Balanced Good 2 or 4Image Reject FairGoodExcellentFair2 Balanced (180°) FairGoodPoorGood2 Balanced (90°) FairGoodFairPoor1Single-Ended Third-Order Intercept Conversion Loss RF-LO Isolation RF Input Match Number of Diodes Mixer

11 Diode Mixer Double balanced BPSK Mixer/Modulator

12 Off-the-shelf Mixer RF2638 Upconverter/BPSK modulator Specs: IF InputLO InputOutput IF to LO Isolation 30 dB-- RF to LO Isolation 30 dB - Noise Figure--14 dB IP3--13 dBm Conversion Loss dB

13 Important Specs Third Order Intercept Point, 1 dB Compression  Figures of merit that describe linearity of device  High IP3 desirable Noise Figure  Noise (in dB) added to amplified signal by amplifier circuitry  Average 1.5 dB for LNA, 5 dB for PA Input and Output Impedances

14 Power Amplifier Boosts the level of the modulated signal for broadcast by the antenna Operates at the carrier frequency Need a specific output power level to achieve the 12dBm transmission power specification

15 Power Amplifier Linx Technologies BBA-519 minicircuits.com amplifier selection guide SpecValue Operating Frequencies 10MHz – 4 GHz Gain (1 GHz)17 dB Noise Figure4.8 dB Output IP3+33 dBm VSWR (in, out)2.1:1, 1.8:1 Max Output Power+17 dBm Operating Voltage (single supply) 4.8 – 5.2 V, 5.2 – 12 V w/ R Operating Current60 mA

16 Antennas Broadcasts/receives the carrier signal Considerations: type, size, connector type, and impedance (typically 50 Ohms) AN-900S RF Antenna from rf-links.com: MHz, 3 in. tall, BNC connector, omni Yagi (directional)Omni-DirectionalDipole

17 Low Noise Amplifier First component of receiving unit Amplifies weak signal picked up from antenna while contributing minimal noise Resulting output is sent to mixer

18 Low Noise Amplifier Choices from various manufacturers  Input impedance will be properly matched with the antenna for an optimal SWR

19 Filter Bandpass filter used to reject unwanted frequency products and pass signals of the selected IF Important Specs  cutoff frequency/center frequency  passband and stopband  insertion loss  out of band attenuation  VSWR

20 Filter Two realization options: One bandpass filter or a low pass filter cascaded with a high pass to create a bandpass filter Filter selection will depend on selected IF Possible filter selections: Model #Filter typeCenter frequency VSWR Passband, Stopband MC LCFN-80Low pass145 MHz1.2:1, 20:1 MC SCLF-95Low pass108 MHz1.7:1, 18:1 MC PHP-150High pass120 MHz1.8:1, 17:1 MC PHP-100High pass82 MHz1.5:1, 17:1

21 IF Amplifier Boosts the level of the filtered IF signal so that it can be accurately demodulated More options for selection due to operation at the IF rather than the carrier frequency

22 IF Amplifier Linx Technologies BBA-322  High gain version of BBA-519 SpecValue Operating Frequencies 10 MHz – 3 GHz Gain (1 GHz)20 dB Noise Figure3.8 dB Output IP dBm VSWR (in, out)2.3:1, 2.1:1 Max Output Power+10 dBm Operating Voltage (single supply) 4.8 – 5.2 V, 5.2 – 12 V w/ R Operating Current35 mA minicircuits.com amplifier selection guide also has options

23 Cost Breakdown Modulator: $9 LNA: $4 Antenna: ? Power Amp & IF Amp: $2 - $15 Filter: $2 - $15 Miscellaneous Components: ? PCB Board and Manufacturing: ?

24 Potential Problems Antenna Selection  Complex design  Physical properties  Impedance matching  Range & frequency considerations Accounting for mismatches in available components Power supply requirements for each component

25 Next Steps Finalize component selection  Impedance matching  Biasing considerations  Signal level Order components Test equipment training Begin testing components

26 Schedule Further component research – Dec. 3 rd Finalized preliminary design – Jan. 17 th  Component list  Cost analysis  Finalized system diagram  DFMEA/Design review issue resolution Place orders for parts – Jan. 21 st Begin PCB layout – Jan. 31 st