[問題]請問varactor的資料

[elian1 (Baseball在面前)]

請問各位前輩
junction varactor和MOS varactor比較的優缺點為何?
我是知道個大概 但由於要寫論文 所以需要詳細的資料
但又不知道這方面的詳細資料要去哪找
還請知道哪裡找的到這些資料的前輩跟我指點一下  感激!!

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※ 編輯: elian1          來自: 140.116.214.108      (05/15 21:49)
※ 編輯: elian1          來自: 140.116.214.108      (05/15 21:51)
※ 編輯: elian1          來自: 140.116.214.108      (05/15 22:06)
推 jyhbna:On the use of MOS varactors in RF VCOs   Andreani, P.
推 sovereignty:http://0rz.net/f81mA ^^
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作者: deathcustom (沒有目指到@@) 看板: comm_and_RF
標題: Re: [問題]請問varactor的資料
時間: Mon May 15 22:20:07 2006

※ 引述《elian1 (Baseball在面前)》之銘言：
: 請問各位前輩
: junction varactor和MOS varactor比較的優缺點為何?
: 我是知道個大概 但由於要寫論文 所以需要詳細的資料
: 但又不知道這方面的詳細資料要去哪找
: 還請知道哪裡找的到這些資料的前輩跟我指點一下  感激!!

Razavi有一篇講到這個

Devices and Circuits for Phase-Locked Systems
Behzad Razavi

一開始就有

主要是Reverse Bias對 J Varactor的效應
而MOS Varactor對此免疫

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推 elian1:感恩!!
> -------------------------------------------------------------------------- <

作者: deathcustom (沒有目指到@@) 看板: comm_and_RF
標題: Re: [問題]請問varactor的資料
時間: Tue May 16 01:02:29 2006

※ 引述《elian1 (Baseball在面前)》之銘言：
: 請問各位前輩
: junction varactor和MOS varactor比較的優缺點為何?
: 我是知道個大概 但由於要寫論文 所以需要詳細的資料
: 但又不知道這方面的詳細資料要去哪找
: 還請知道哪裡找的到這些資料的前輩跟我指點一下  感激!!

     As supply voltages scale down, pn junctions become a less
attractive choice for varactors. Specifically, two factors limit
the dynamic range of pn-junction capacitances: (1) the weak
dependence of the capacitance upon the reverse bias voltage,
e.g., Cj = Cj0/(1+Vr/Φb)^m, where m ~ 0.3.; and (2) the
narrow control voltage range if forward-biasing the varactor
must be avoided.

http://www2.ee.ntu.edu.tw/~b1901050/16-05-06_0055.jpg

     As an example, consider the LC oscillator shown above.
It is desirable to maximize the voltage swings at nodes X and
design of the stage(s) driven by the VCO. On the other hand,
to avoid forward-biasing the varactors significantly, Vx and
Vy must remain above approximately Vcont - 0.4V. Thus,
the peak-to-peak swing at each node is limited to about 0.8V.
Note that the cathode terminals of the caractors also introduce
substantial n-well capacitance at X and Y, further constraining
the tuning range.

     In contrast to pn junctions, MOS varactors are immune to
forward biasing while exhibiting a sharper C-V characteristic
and a wider dynamic range. If configured as a capacitor(as
below), a MOSFET suffers from both a nonmonotonic C-V behavior
and a high channel resistance in the region between accumulation
and strong inversion. To avoid these issues, an "accumulation-mode"
MOS varactor is formd by placing an NMOS device inside an n-well......

http://www2.ee.ntu.edu.tw/~b1901050/16-05-06_0056.jpg
http://www2.ee.ntu.edu.tw/~b1901050/16-05-06_0057.jpg

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推 Ccwind:感謝  但近拍技術需要加強
推 deathcustom:那是手機拍的，抱歉......><