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Semiconductor Microwave Devices

Microwave Engineering/Active Microwave Devices 9-13 September 2006. 2. Microwave Diodes. A microwave diode is much more than just a two-element device which has limited capabilities. It is a complex device which an integral part of many sophisticated microwave systems. Many devices have been developed using the non-linear I-V and C-V characteristics of the p-n or Schottky-barrier junction. Various applications are summarized below .

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Semiconductor Microwave Devices

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    1. Microwave Engineering/Active Microwave Devices 9-13 September 2006 1 Semiconductor Microwave Devices

    2. Microwave Engineering/Active Microwave Devices 9-13 September 2006 2

    3. Microwave Engineering/Active Microwave Devices 9-13 September 2006 3 Non-Linear Characteristics of p-n and Schottky diodes

    4. Microwave Engineering/Active Microwave Devices 9-13 September 2006 4 Varactor Devices and Circuits

    5. Microwave Engineering/Active Microwave Devices 9-13 September 2006 5 Applications: (1) Voltage controlled Oscillator VCO: ? FM systems and frequency agile systems ? Instrumentation ? Electronic warfare (EW) ? Electronic counter measurement (ECM) systems.

    6. Microwave Engineering/Active Microwave Devices 9-13 September 2006 6 (2) Multiplier and harmonic generation Feasible alternative for the generation of high frequency signal

    7. Microwave Engineering/Active Microwave Devices 9-13 September 2006 7 (3) Parametric Amplifiers: Provide very low noise amplification

    8. Microwave Engineering/Active Microwave Devices 9-13 September 2006 8 p-i-n Diodes Similar to the pn diode with smaller junction capacitance Very useful for a diode used a microwave switch

    9. Microwave Engineering/Active Microwave Devices 9-13 September 2006 9 Switches Applications

    10. Microwave Engineering/Active Microwave Devices 9-13 September 2006 10 (4) Channel selection in wideband system (5) Signal path control in measurement systems As a switch the main important p-i-n diode parameters are Isolation and Insertion loss

    11. Microwave Engineering/Active Microwave Devices 9-13 September 2006 11 p-i-n Diode Attenuator p-i-n diode attenuator circuits are used extensively in automatic gain control (AGC) and RF leveling applications as well as in electronically controlled attenuators and modulators

    12. Microwave Engineering/Active Microwave Devices 9-13 September 2006 12

    13. Microwave Engineering/Active Microwave Devices 9-13 September 2006 13 p-i-n Phase Shifters

    14. Microwave Engineering/Active Microwave Devices 9-13 September 2006 14 Switched line phase shifter

    15. Microwave Engineering/Active Microwave Devices 9-13 September 2006 15 Limiter p-i-n Diodes Used for protection applications

    16. Microwave Engineering/Active Microwave Devices 9-13 September 2006 16

    17. Microwave Engineering/Active Microwave Devices 9-13 September 2006 17

    18. Microwave Engineering/Active Microwave Devices 9-13 September 2006 18 Gunn Diodes Single piece of GaAs or Inp and contains no junctions Exhibits negative differential resistance Applications: low-noise local oscillators for mixers (2 to 140 GHz). Low-power transmitters and wide band tunable sources Continuous-wave (CW) power levels of up to several hundred mill watts can be obtained in the X-, Ku-, and Ka-bands. A power output of 30 mW can be achieved from commercially available devices at 94 GHz. Higher power can be achieved by combining several devices in a power combiner. Gunn oscillators exhibit very low dc-to-RF efficiency of 1 to 4%.

    19. Microwave Engineering/Active Microwave Devices 9-13 September 2006 19 Varactor Tuned Gunn Oscillators Circuits

    20. Microwave Engineering/Active Microwave Devices 9-13 September 2006 20

    21. Microwave Engineering/Active Microwave Devices 9-13 September 2006 21 IMPATT Devices and Circuits IMPact Ionization Transit Time IMPATT devices can be used for oscillator and amplifier applications They can be fabricated with Si, GaAs, and InP Can be used up 400 GHz. Noisy oscillator In general, IMPATTs have 10 dB higher AM noise than that of Gunn diodes IMPATT diode is not suitable for use as a local oscillator in a receiver.

    22. Microwave Engineering/Active Microwave Devices 9-13 September 2006 22 Some IMPATT Circuits

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