1 / 29

رفتار فركانسي تقويت كننده هاي ترانزيستوري

رفتار فركانسي تقويت كننده هاي ترانزيستوري. پاسخ فركانسي تقويت كننده ها.

jarroda
Télécharger la présentation

رفتار فركانسي تقويت كننده هاي ترانزيستوري

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. رفتار فركانسي تقويت كننده هاي ترانزيستوري

  2. پاسخ فركانسي تقويت كننده ها • بيان تابع تبديل يك سيستم بر حسب فركانس است كه مي تواند به صورت منحني تغييرات دامنه تابع تبديل بر حسب فركانس نمايش داده شود. در صورتي كه سيستم مورد نظر يك تقويت كننده باشد، تابع تبديل همان بهره تقويت كننده است كه در حالت كلي وابسته به فركانس مي باشد.

  3. محدوده هاي فركانسي • فركانسهاي پائين • فركانسهاي مياني • فركانسهاي بالا

  4. محدوده فركانسهاي پائين • در فركانسهاي پائين بهره تقويت كننده ها شروع به افت مي نمايد. دليل آن استفاده از خازنهاي كوپلاژ و كنار گذر در مدار تقويت كننده است.

  5. محدوده فركانسهاي بالا • در فركانسهاي بالا تاثير خازنهاي داخلي ترانزيستورها بهره تقويت كننده را كاهش مي دهد.

  6. محدوده فركانسهاي مياني • بهره تقويت كننده در اين باند ثابت است. • از تجزيه و تحليل مدار كه به روشهاي متنوعي صورت مي گيرد بهره قابل محاسبه است.

  7. محاسبه بهره در باند مياني • ابتدا منابع مستقل راصفر كرده، و خازنهاي خارجي ( كوپلاژ و كنار گذر ) را اتصال كوتاه مي كنيم. سپس شبكه حاصل را حل كرده و نسبت خروجي به ورودي را بدست مي آوريم.

  8. محاسبه فركانس قطع پائين • تابع شبكه در فركانسهاي پائين را برحسبS=jw به دست آورده و اندازه آن را 707/0 برابر مقدار حداكثر اندازه تابع شبكه قرار مي دهيم.از حل معادله جبري حاصل فركانس قطع پائين بدست مي آيد.

  9. محاسبه فركانس قطع بالا • تابع شبكه در فركانسهاي بالا را برحسبS=jw به دست آورده و اندازه آن را 707/0 برابر مقدار حداكثر اندازه تابع شبكه قرار مي دهيم.از حل معادله جبري حاصل فركانس قطع بالا بدست مي آيد.

  10. تجزيه و تحليل قطعات و مدارها در فركانسهاي بالا

  11. MidBand Equivalent High Frequency Equivalent AC Equivalent Circuit for BJT & FET

  12. The Miller equivalent circuit.

  13. Figure 6.16 Circuit for Example 6.7.

  14. Figure 6.20 High-frequency equivalent-circuit model of the common-source amplifier. For the common-emitter amplifier, the values of Vsig and Rsig are modified to include the effects of rp and rx; Cgs is replaced by Cp, Vgs by Vp, and Cgdby Cm.

  15. Figure 6.21 Approximate equivalent circuit obtained by applying Miller’s theorem while neglecting CL and the load current component supplied by Cgd. This model works reasonably well when Rsig is large and the amplifier high-frequency response is dominated by the pole formed by Rsig and Cin.

  16. Figure 6.22 Application of the open-circuit time-constants method to the CS equivalent circuit of Fig. 6.20.

  17. Figure 6.23 Analysis of the CS high-frequency equivalent circuit.

  18. Figure 6.24 The CS circuit at s5sZ. The output voltage Vo5 0, enabling us to determine sZ from a node equation at D.

  19. Figure 6.25 (a) High-frequency equivalent circuit of the common-emitter amplifier. (b) Equivalent circuit obtained after the Thévenin theorem is employed to simplify the resistive circuit at the input.

  20. Figure 6.26 (a) High-frequency equivalent circuit of a CS amplifier fed with a signal source having a very low (effectively zero) resistance. (b) The circuit with Vsig reduced to zero. (c) Bode plot for the gain of the circuit in (a).

  21. Figure 6.31 (a) The common-gate amplifier with the transistor internal capacitances shown. A load capacitance CL is also included. (b) Equivalent circuit for the case in which ro is neglected.

  22. Figure 6.38 The cascode circuit with the various transistor capacitances indicated.

  23. Figure 6.42 Determining the frequency response of the BJT cascode amplifier. Note that in addition to the BJT capacitances Cp and Cm, the capacitance between the collector and the substrate Ccs for each transistor are also included.

  24. Figure 6.51 Analysis of the high-frequency response of the source follower: (a) Equivalent circuit; (b) simplified equivalent circuit; and (c) determining the resistance Rgs seen by Cgs.

  25. Figure 6.52 (a) Emitter follower. (b) High-frequency equivalent circuit. (c) Simplified equivalent circuit.

  26. Figure 6.54 Circuits for Example 6.13: (a) The CC–CE circuit prepared for low-frequency small-signal analysis; (b) the circuit at high frequencies, with Vsig set to zero to enable determination of the open-circuit time constants; and (c) a CE amplifier for comparison.

  27. Figure 6.56 (a) A CC–CB amplifier. (b) Another version of the CC–CB circuit with Q2 implemented using a pnp transistor. (c) The MOSFET version of the circuit in (a).

  28. Figure 6.57 (a) Equivalent circuit for the amplifier in Fig. 6.56(a). (b) Simplified equivalent circuit. Note that the equivalent circuits in (a) and (b) also apply to the circuit shown in Fig. 6.56(b). In addition, they can be easily adapted for the MOSFET circuit in Fig. 6.56(c), with 2rp eliminated, Cp replaced with Cgs, Cm replaced with Cgd, and Vp replaced with Vgs.

More Related