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# Varactor Design

81 Threads found on edaboard.com: Varactor Design

## Handle insertion loss variation of Analog Phase Shifter based on Varactor Diode

my guess is that your varactor diode is not actually "series resonated", as is required in the first step of the paper. That tiny series inductor has to be carefully chosen so that the phase shift is on the order of 0 to 270 degrees as the voltage swings from zero to Vmax . Normally, without the series inductance, you would not get even half of

## How to create Varistor in CST?

Hi everyone, I need to help with my project in CST MWS. I have to do design of an Electronically Beam Scanning Reflectarray Using Aperture-Coupled Elements as in link: but in 24 GHz. I dont know, how to do a model of varactor diode MGV-100-20 in CST.

## How can i bias Varactor Diode in my design?

Hi I'm designing an phase shifter and i have to use 2 varactor Diode How can i bias This phase shifter without any dc block in phase shifter. phase shifter has 2 port by the way and I'm wondering how can i bias this varactors? 119174

## Question about varactor (VCO design)

Hi, I?m reading materials about VCO design for reference, and in one of them there is something I can?t understand: ?Substituting this result gives Cv = 675fF. Because the varactor is in series with a 5pF AC coupling MIM capacitor, its actual value should beincreased to about 790fF.? Why exactly we should increase the value of Cv? Than

## Help with VCO Design

Hi, I have a project to design a VCO which i have difficulties with. Could someone please help me out? I have the following specifications: band: 1430 to 2230 MHz comparison frequency: 7.8125 kHz VCO output power: 10 mW I don't know how to find the value of the needed varactors and the s-parameters. I would be eternally grateful for t

## simple VCO circuit with BJT

What are the design goals? Is it supposed to oscillate at 50MHz with the varactor diode in place? I agree with others that your problem is caused by the 270uH inductor. This can be seen when we do a open-loop analysis on the circuit. There are two frequencies (one low and one high frequency) that the circuit wants to oscillate at. Replace t

## How to convert RF balanced output to unbalanced with improved harmonics level?

LO is about 2GHz, 0dBm. Idea is to try N multiplication without using additional amplification stages. I read about varactor multipliers are good efficiency, but diffictult to design for good performance. @CW: Yup, non-linear devices (unless they are amplifiers) in an RF path at this frequency can be detrimental

## How to choose the MOS varactor

Dear all Have you used the MOS varactor in the LCVCO design. There are NMOS varactor and PMOS varactor, what is the difference of them, and which type of varactor is fit for the LCVCO design. Thank you very much.

## How much leakage current is tolerlable in a varactor stack?

I'm trying to design a varactor stack like figure 2 (d) here: and I'm getting confused by a varactor's typical reverse leakage current rating. I've found varactors with only 20nA leakage but it seems like even that would forward bias one of the diodes. It seems like, no mat

## VCO design quuestion (centre frequency)

You have to first decide on the varactor, either max or min capacity. If minimum capacity, add a bit on for stray capacity. Now work out your inductance for the maximum frequency. Repeat using figure for varactor max cap (+stray C) and if you are in luck it will be lower frequency then required. if not you need a better varactor. remember, (...)

I am designing LC VCO using PMOS varactor in ADS. In typical LC VCO, L and C values are selected according to the formula f=1/√LC. How to find the PMOS varactor width values?. Also oscillation frequency versus control voltage is plotted for this VCO. very small variation in the oscillation frequency only obtained. Anybody (...)

## why a vco is nonlinear ?

It depends on the varactor curve, and the LC formula - freq will vary proportional to sqrt(1/C), so it's non-linear.

## Mini FM transmitter of own construction

Classic design.. Consider 50% less solder needed next time but heavy parts may need PU adhesive on comp side. Consider BB187 more readily avail. varactor diode. with 11:1 ratio and good matching.

## Need help to design a Sine curve multiplier

A tuned multiplier will not increase the jitter. A PLL type approach will. Yes, if we ignore a small noise induced jitter contribution of the varactor diode, or whatever is used as frequency multiplier. The succeeding comparator converting the 240 MHz sine into the required square wave will show some more jitter, but 1-2 ps seems re

## Simple FM Modulator Design

The Armstrong FM modulator is the choice for you request, but is much complicated than using a simple varactor part of the resonant circuit. See the original block diagram and schematic, from Armstrong patent file in 1936.

## Problem: Varactor Based Phase Shifter Design

The shape in the picture is not a branch line coupler. To bias the varactors, instead using an inductor connected to the middle of the coupler, try using two resistors (~100k)