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Phase Noise to Jitter Converter

The calculator uses piece-wise linear approximation of the phase noise curve to compute the RMS jitter (integrated phase noise). Like similar calculators, it assumes that left and right noise sidebands are the same.

The phase noise is integrated using trapezoidal elements as shown:

(Frequency is on log scale)


Center Frequency: GHz
Offset, Hz Phase Noise, dBc/Hz  
RMS Jitter: deg

Planar Spiral Inductor Calculator

A Planar Spiral Inductor Calculator based on "Lumped Elements for RF and Microwave Circuits" by Inder Bahl.

Main purpose of this calculator is to compare Inductance, Q and resonant frequency and how they are scaled with inductor parameters. It's not very accurate in absolute sense. From limited 3d EM simulations, the inductance is fairly accurate (within 5-10%). But, inductor Quality factor (Q) is overly optimistic. 3D EM simulation shows Q about half or less of the calculated values. Resonant frequency is typically lower than calculated, by about 10%. The inductor is meant to be driven differentially, and effects of the airbridge and terminals are neglected.

Conditions: W>H/20.

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Distance units: 

Substrate Height, H  
Winding trace Width, W  
Winding trace Thickness, T (1oz=1.4mil)
Inter-winding gap, S  
Outer inductor diameter, Do  
Dielectric Constant, er (FR4: 4.2-4.8)
Metal conductivity s (S/m) (gold:4.10e7, copper:5.96e7)
Number of turns, N  
Test frequency, Freq GHz
Inner inductor diameter, Di  
Low frequency inductance nH
Effective Inductance @ Freq nH
Inductor Quality Factor @ Freq  
Resonance frequency GHz

Trace Inductance Calculator

Trace Inductance calculator for wide traces over a ground plane with trace width (W) much larger than substrate thickness (T). Relative Permeability is assumed to be 1. Low frequency, perfect conductor: no skin effect.

Conditions: W>>H, H>T


Wide trace cross section

trace inductance formula 
Distance units: 
Substrate Height, H  
Trace Width, W  
Trace Thickness, T (1oz=1.4mil)
Trace Length, L  
Low frequency inductance nH

Microstrip line calculator

Based on Planar Microwave Engineering by T. H. Lee

Typical error <10%, if parameters within the conditions. Error is less for 25 ohm to 100 ohm Z0.

Conditions: W>H, T<H.



Distance units: 

Substrate Height, H  
Trace Width, W  
Trace Thickness, T (1oz=1.4mil)
Dielectric Constant (FR4: 4.2-4.8)
Intrinsic Impedance, Z0 Ohm
Fc (transverse res.) GHz
Ft (surface wave onset) GHz

CPW (grounded) line calculator

A Grounded CPW transmission line calculator. Verified with Agilent LineCalc and Agilent Momentum simulations.

Typical error is a <10%, but could be more if taken outside recommended ranges.

Conditions (weak microstrip mode, low side capacitance):

S>>T,  H>T,  0.125 × W ≤ S ≤ 4.5 × W,  W + 2 × S ≤ 5 × H, dielectric constant >3 for higher accuracy.

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Distance units: 

Substrate Height, H  
Trace Width, W  
Thickness, T (1oz=1.4mil)
Gap, S  
Substrate Dielectric Constant, Er (FR4: 4.2-4.8)
Effective Er  
Intrinsic Impedance, Z0 Ohm

LC resonator calculator

LC resonator calculator. Calculates L, C, or resonant frequency, given the other two parameters.

Leave the field which needs to be computed empty (after a computation, if all fields are non-empty then previous field will be computed).

L, Inductance
C, Capacitance
Fres, Resonant Frequency

Via Inductance

Via inductance calculator based on "Modeling Via Grounds in Microstrip" IEEE Microwave and Guided Wave Letters, Vol. 1, No. 6, June 1991, by Goldfarb and Pucel. This calculator is valid only for vias connecting microstrip lines to the ground plane with no return paths on the top layer (ie. no coplanar modes).


Distance units: 

Substrate Height, h  
Diameter, d  
Inductance, Lvia pH

IP3 calculator

IP3 calculator - calculates either IM3, P_out or IP3, given the other two parameters. Voltages are referenced to 50 Ohms. If output power is combined power of 2 tones, then IM3 is also combined (left+right) power. If output power is per tone, then IM3 is also per tone. Both sides are assumed to be equal, if not, then use total powers (Pout total and IM3 total).

Leave the field which needs to be computed empty (after a computation, if all fields are non-empty then previous field will be computed).

Output IP3 (OIP3)
Output Power
(Output) IM3

PLL loop filter calculator

PLL loop filter design for optimum integrated phase noise based on specified PLL parameters (Charge pump current, Icp, Divider N=Fout/Fref), VCO and Reference phase noise.


Look at the intersection of the open loop phase noise of your Reference (scaled by 20log(N), where N is Fout/Fref) and VCO open loop phase noise. The intersection of these two curves is fxsect, and the corresponding angular frequency is ωxsect=2πfxsect.

Note the slope of the VCO open loop phase noise around the intersection (dB/decade). You can estimate it by looking at a decade offset in both directions, calculating the phase noise difference and dividing by 2.



Capacitance ratio, r=C1/C2 (as shown below), is typically bigger than or equal to 10. Integrated phase noise improves by about 10% when r is changed from 5 to 10, by additional 5% when going from r=10 to r=15, and by additional 2% going from r=15 to r=25. The choice of r depends on many things, such as: the required spurious suppression, settling time and filtering of the loop resistor noise.

NOTE: Loop resistor noise is assumed to be negligible. Reference phase noise is assumed to be flat around the intersection frequency, fxsect.

The loop filter topology:

Intersection frequency fxsect KHz
Charge pump current, Icp mA
VCO tuning sensitivity, KVCO MHz/V
Fout/Fref division ratio, N  
Capacitance ratio, r  
VCO slope at intersection dBc/Hz/Decade
Damping constant  
Natural Frequency, ωnxsect rad/s
Resistor Ohm
C1 nF
C2 nF


Verification using ADIsimPLL 3.3.

Parameters used: r=C1/C2=10, VCOslope=29 dBc/Hz2, Kvco=200 MHz/V, Icp=5 mA, fxsect =17 KHz, N=288, Ref PN= -80dBc/Hz at 14.4GHz (Fout). Which leads to the following loop filter values: R=39, C1=587nF, C2=58.7nF. (Note: C1/C2 are reversed in ADIsimPLL).

The following figure shows closed loop phase noise with the optimum loop filter working at 14.4GHz:


The table below shows the results of varying loop parameters to show that the calculator works as intended.

Values are integrated phase noise in degrees.

  C1, C2
-30% 0 +30%
R -30% 2.38 2.37 2.38
0 2.32 2.31 2.32
+30% 2.32 2.32 2.32

Attenuator Calculator

PI pad attenuator calculator for different input and output impedances with suggestion for standard closest resistors (best return loss)

RF PI pad resistive attenuator schematic
Input Impedance: Ohm
Output Impedance: Ohm
Desired Attenuation: dB
Min. Return Loss: dB
 Using ideal resistor values (infinite return loss):
Rpi: Ohm
Rpo: Ohm
Rs: Ohm
 Using closest standard resistor values:
Rpi: Ohm
Rpo: Ohm
Rs: Ohm
Actual Attenuation: dB 
Input Return Loss: dB 
Output Return Loss: dB 
Custom Resistor Values:
(space separated sorted list. can use 'R', 'K', 'M'. Ex. 0R1 11.3 1K21 1M01 1.50M)

Resistor values...