1 / 82

FM Transmitter

FM Transmitter. FM Modulation using VCO. [1]. f out. V in. - Free Running Frequency of VCO. Corresponding DC bias. - Gain of VCO. Block Diagram. PA. . VCO. Input. DC Bias Vcc/2. Chipset. 4046 Phase-Locked Loop LM7171 Wide-Band Power Amplifier 741 Op Amp. 4046 PLL .

vahe
Télécharger la présentation

FM Transmitter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FM Transmitter

  2. FM Modulation using VCO [1] fout Vin - Free Running Frequency of VCO Corresponding DC bias - Gain of VCO

  3. Block Diagram PA  VCO Input DC Bias Vcc/2

  4. Chipset • 4046 Phase-Locked Loop • LM7171 Wide-Band Power Amplifier • 741 Op Amp

  5. 4046 PLL Only use the VCO

  6. 4046 VCO Characteristic C1>=100pF

  7. Schematic

  8. PCB Layout Considerations • The signal traces should be short and wide to lower the impedance. • The width of the signal traces has to satisfy current driving capacity. • Any used board area should be shorted to ground to reduce AC noise. • Sockets and pads will induce extra capacitance, so components should be directly soldered to board. • Surface mount components are preferred over discrete ones for less lead inductance.

  9. PCB Layout

  10. Measured Results • Carrier Frequency: 15MHz • Bandwidth: Controllable • Output Power: 500mW

  11. FM Receiver

  12. FM Demodulation using PLL [2] PFD LF Ve in VCO

  13. Loop Filter Design [3]

  14. VCO Design • VCO free running frequency = Carrier Frequency • VCO Frequency Range is no smaller than Bandwidth • Large VCO gain will increase PLL natural frequency n and thus improves PLL tracking capability

  15. Block Diagram LNA Amp BPF PFD LF VCO

  16. Chipset • 4046 PLL • CLC425 Wide-band LNA

  17. 4046 PLL

  18. Schematic

  19. PCB Layout

  20. Superheterodyne FM Receiver

  21. Block Diagram IF Amp + IF Filter Input Matching Mixer Amp FM Demodulator LO

  22. Chipset • TDA7000 – FM Radio • LM3875 – Audio Power Amplifier

  23. TDA7000 [4]

  24. IF Filter

  25. Quadrature Demodulator Vout fin

  26. IF Harmonic Distortion IF=70kHz

  27. IF Distortion Suppression FLL

  28. Correlator To suppress interstation noise • Not Modulated • Lightly Modulated • Heavily Modulated

  29. Schematic

  30. PCB Layout

  31. Monolithic FSK Transmitter [5]

  32. PLL Reference Frequency Output Dual Modulus Prescaler Digital Input A/D Converter Shift Register Analog Input Clock Data Sampling Rate Block Diagram

  33. Inverter

  34. NAND – 2 Input

  35. NAND – 3 Input

  36. NAND – 4 Input

  37. NOR – 2 Input

  38. XOR

  39. Transmission Gate

  40. Edge-Triggered D Flip-Flop

  41. D Flip-Flop with ‘CLEAR’

  42. Voltage Comparator

  43. 8-to-3 Encoder

  44. A/D Converter

  45. Parallel-Serial Shift Register

  46. Phase-Frequency Detector

  47. VCO

  48. Dual Modulus Prescaler [6]

  49. Output Driver To drive capacitive load with minimum delay

  50. Capacitor Driving Capability CL=100p f=50MHz

More Related