帮忙讲一下这个VCO的pcb如何布局
输出频率在600-1200MHz准备用1mm厚的FR-4板做
http://cache.amobbs.com/bbs_upload782111/files_44/ourdev_666979KFGFDH.jpg
(原文件名:c.jpg)
http://cache.amobbs.com/bbs_upload782111/files_44/ourdev_666980ZSNA1B.jpg
(原文件名:v.jpg) 又是0回复？
没人有这方面的经验? 关注。。 这个电路应该不对，看起来毛病不少！ 走线太長变成电感或是微带线,尤其低阻抗线路径要缩短長度。C3到集极太長。得L1变成大大于5nH 。C3值太大,需确定能否振盪。 回复【3楼】catvevs
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喔？说说？
电路是一个vco集的外国网站找的。 这个分布参数要用什么工具仿真,老手机上的模块用的是集中参数电路,加微调
楼主的条件太好了,很羡慕 回复【6楼】1ongquan
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没仿真，ads中找不到bb135所以....而且ads中我仿不来VCO
谁能指导下？？
电路来自于：
http://www.qsl.net/va3iul/High_Frequency_VCO_Design_and_Schematics/High_Frequency_VCO_design_and_schematics.pdf
The Vackar VCO circuit incorporates a π-section tank to attain the needed 180° phase-reversal in the
feedback loop.
· However, the inverted feedback signal is not directly fed back to the input of the active device; rather,
it is loosely coupled through a small capacitor. Often, a shunt capacitor is introduced to further
reduce the coupling.
· The basic idea is to isolate the resonant circuit as much as possible from the input of the active
device, consistent with obtaining reliable oscillation.
· This circuit is particularly advantageous with solid-state devices, and especially with bipolar
transistors that have inordinately-low input impedances and that present a widely-varying reactance
to the tuned circuit as a consequence of temperature and voltage changes.
· Once the overall circuit is operational, the values of capacitance C1 in series with Cvar and collector
capacitance (C2) may be optimized for best stability. Generally, it will be found that the capacitor
closest to the collector of the transistor can be several times larger than the capacitor associated with
the base circuit.
· The introduction of attenuation in the feedback loop (via the small capacitor in the Vackar) prevents
over-excitation and effectively isolates the resonant circuit from the active device.
· The frequency tuning range of Vackar VCO is above one octave, not observable to many oscillator
types.
· The frequency tuning is provided independently of the coupling to the LC tank circuit.
· The parametric variables of the transistor (which depends by the bias current and temperature), are
isolated from the resonator.
· The transistor input is not overloaded as other VCO circuits and the collector output has low
impedance providing low gain just to maintain the oscillation.
· The feedback division ratio is fixed (typical range for coupling ratio is 1:4 up to 1:9). Even if the VCO
is tuned, the impedance divider is fixed, in this way increasing the stability.
· Two negative sides of Vackar VCO are the critical starting oscillation point, and the low output level,
which always requires using a buffer amplifier. When the oscillation doesn’t start means that it 这样不行，还要加一级缓冲放大， 回复【8楼】mdj-fish
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能给个电路吗？
要是有高手给个电路，仿真下，给个Pcb学习下。
因为平时比较少看到可以参考的布局。 mark 关注一下 继续自己顶... http://cache.amobbs.com/bbs_upload782111/files_44/ourdev_667369MXT9EY.jpg
(原文件名:vv.jpg)
改了下。
不知道有谁有经验的帮忙仿真下这个电路。 带宽主要由那个变容管决定，所以一定要想办法减小分布电容 回复【15楼】yuhang
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楼上高手，知道你是这个专业的。
能不能再给点更详细的？上面这个PCB图能用不？这方面没经验。 电阻电容都是0603的，格点是0.25mm的。
找很久都没找到有什么宽带vco的pcb，没法借鉴。
PCB文件
点击此处下载 ourdev_667388RT9ESM.rar(文件大小:226K) (原文件名:600-1200MHz VCO.rar) 自己再顶
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