Suggestions about inductorless VCOs above 3 MHz frequency

[gunturikishore]

Hi,

Does anybody have any design ideas and papers about VCOs about 3 GHz without inductor. Please suggest me some papers in this topic. Thanks in advance for the suggestions. I need specifically in CMOS technology.

 

[mvs sarma]

Perhaps you use Striplines as inductors and the oscillators with stripline are common. You may have to use Duroid PCB material. Also, PLL type oscillators are also used with basic oscillator being crystal. Here you need to search for prescalers at GHz range.

Sarma

 

[raghav]

Re: Suggestions about inductorless VCOs above 3 MHz frequenc

One way to design a VCO would be to build a ring oscillator, and control the supply. The "output" is almost "linear" around a center frequency. This should help.

 

[ee07d003]

Re: Suggestions about inductorless VCOs above 3 MHz frequenc

I agree with Raghav's reply. Controlling the supply of the ring oscillator should give "near-linear" performance. In fact, the phase noise "rejection" is better too, as the noise gets added only after certain number of cycles. The following link should help too. **broken link removed**

 

[nandu]

Re: Suggestions about inductorless VCOs above 3 MHz frequenc

@ee07d003
What do you mean by "noise gets added only after a few cycles"?

Added after 14 minutes:

@gunturikishore

You can make oscillator tank circuit similar to an LC tank using capacitor alone with transconductors connected in positive feedback as shown in the diagram. The circuit shown behaves as an inductor of value C/(gm^2) and can be used in place of the inductor of an LC tank.