# Recent content by deba_fire

1. ### Multi element matching using the Smith chart

Re: Multi element matching using Smith chart Thanks for useful suggestions FvM and vfone. Two element matching is very straightforward using Smith charts. For multi-element matching, one needs to use the numerical method similar to any filter design. You have mentioned RF simulator for for...
2. ### Multi element matching using the Smith chart

Multi element matching using Smith chart Hi Multi element matching is needed for separating optimizing the Q and bandwidth of the circuit. For multi element matching(>3) components, how does one go about this using Smith charts? As for multi element there are an infinite paths to reach the...
3. ### DC block connector vs capacitor

Thanks all for the comments. It is a capacitor embedded in a coaxial line tuned for low SWR.
4. ### DC block connector vs capacitor

Hi FvM, So the capacitor is realized using coaxial lines. There is no physical SMD like capacitor. Is there a reference where such a coaxial transmission line design is carried out which I can refer? Thanks
5. ### DC block connector vs capacitor

Hi, The DC block connector available from various manufacturers such as https://weinschel.apitech.com/weinschel/pdfiles/wmod7006-1.pdf support a particular frequency range. My question is why can't a capacitor with appropriate matching can be used instead of these DC block connectors? How are...
6. ### Difference between a single differential pair CMFB and double differential pair CMFB

The first diagram which you are saying as double differential pair is slightly non-linear compared to the second one. The first one uses transistor as common mode detector and the common mode current is detected. In the second one, since only resistors are used to detect the common mode it might...
7. ### Equivalent circuit for TE, TM propagation modes

Hi biff44, Thank you for your answer. Can you please point me to some reference on this? Thanks
8. ### Equivalent circuit for TE, TM propagation modes

Hi, TEM propagation mode which usually happens in almost all two plate conductors, can be represented equivalently by the famous LC ladder network. For TE/TM modes, is there an equivalent circuit representation? Thanks
9. ### frequency folding due to aliasing in FFT

X[k] = $\sum_{n = 0}^\N-1$x[n]${e }^{-j*2*pi*k*n/N }$, k=0 to N-1. From this definition, if you evaluate the exponential for n>N/2 the frequencies will come out to be positive. And vice-versa for n<N/2. The upper half of the unit circle is +ve freq. and the bottom half represents -ve freq.
10. ### [SOLVED] Positive and Negative outputs in active inductor VCO

It depends on the DIVIDER, PFD, LO driver circuitry. If they are differential use both, gives advantage for common mode rejection. But if they are single ended, just use one of them.
11. ### VCO phase noise problems

Calibre for VCO core circuitry. For Inductor, I assume you have used a 3D simulator as I mentioned in my previous post. You need to check the effect of BW on phase noise to conclude its source.
12. ### VCO phase noise problems

Are your simulations settings accurate? How did you extract inductor? Are you using any electromagnetic simulator(Sonnet, EMX etc.) for your inductor model? 20 dB is a huge difference.
13. ### [Moved]: SNR calculation in Sigma-delta modulator

Re: SNR calculation in Sigma-delta modulator Show the spectrum of the DSM output. Are you windowing the data?
14. ### DLL bias voltage unstable when adding capacitor

You have a type 2 system. With one integrator from charge pump and the other from VCO. You need to add a zero. Place a resistor in series with capacitor after the charge pump. The zero location should be within the unity gain bandwidth of your open loop response.
15. ### Current cancellation technique improves linearity

Re: current cancellation technique in OTA The small signal current carried by M1 is cancelled by MN' and vice-versa for M2.