CDKF-R_E_Rev6（2012/9/10）1/7

Common Mode Filter＜Common Mode Eliminator＞
CDKF-Type R-Suffix
1. Features
CDKF type-R is based on our current CDKF-type delay line. We have added the functionality toeliminate common mode noise in differential signal transmissions and created the Common ModeEliminator. It corresponds to the transmission speed of 10Gbps.
It has become necessary to have a plan to deal with common mode noise which is generated frominterval skew in differential signals in ultra-high-speed serial differential signal transmissions.
Developed to deal specifically with this necessity, this product automatically eliminates interval skew
common mode noise internally.
The input common mode noise is offset within the delay line structure from the partially-reflectedcommon mode noise, the noise is not superimposed.
Also, because it is non-magnetic, there is no magnetic loss. It is well-suited for dealing with common
mode noise from high-speed differential signal transmissions over 6Gbps.
Also, because this product is based on our CDKF-type delay line, to which we have added functionality
to eliminate common mode noise, we can also add our guarantee the accuracy of our delay lines.
This product is a layered ceramic chip type LTCC part and is RoHS-compliant.
S-parameter files (Touchstone format) and SPICE models can be provided.

2. Common Specifications （provisional）
Input/Output Impedance:Differential 100Ω±10% *Interval Skew Auto-Adjust Time
:1/4Pw (Pw Spec: 1Unit Interval pulse width <200ps)
Waveform Distortion:Overshoot/Preshoot under ±20%Output Rise Time
:45ps Typ. (20%-80%)
DC Resistance:1Ω Max.
Delay Time Temp. Coefficient:0～150ppm/℃
Insulation Resistance:DC50V, over 100MΩ
Durable Voltage:DC50V, 1 minuteRated Current:100mA
Rated Voltage:5V
Operating Temperature Range:－40℃ to +85℃
Storage Temperature Range:－40℃ to +120℃* Single-ended operation will not produce usable waveforms.
Part Number
CDKF10R

Transmission Speed(1)*
6G～10Gbps-3dB Passband (1)*Delay Time

DC～15GHz Typ.

100ps±25ps(1)* When using the recommended Land Pattern.

ELMEC Corporation

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3. Package Dimensions and Pin Configuration （provisional）
Unit: mm(inch), Tolerance: ±0.15(0.006)

4. Suggested Land Pattern
Unit: mm(inch), Tolerance: ±0.1(0.004)
Example for Dielectric Layer
Dielectric Layer (εr)

GND Planeεr, t and Wtεr
3.5
4.1

0.3(0.012)
W=0.56(0.022)
W=0.50(0.020)

0.4(0.016)
W=0.70(0.028)
W=0.64(0.025)

0.5(0.020)
W=0.78(0.031)
W=0.70(0.028)

ELMEC Corporation

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5. Suggested Reflow Soldering Conditions
J-STD-020C Pb-Free Standard
Storage conditions are as per MSL1. These component families are not moisture-sensitive. Baking prior
to reflow is not required.
Maximum Cycles: 3x

6. Typical Applications
ECL (-2V termination line used)

LVPECLPECLLVDS* Please be sure to connect the GND Termination. (Please See Notes)
7. RoHS Compliance Status
RoHS-compliant
8. Notes
Always connect the GND terminals. Using this product without connecting the GND could cause
deterioration of the common mode noise elimination and delay line functions.
Also, use of only one line will not yield a normal wave form and cannot be used.

ELMEC Corporation

CDKF-R_E_Rev6（2012/9/10）4/7
9. Characteristics Examples
9-1 Frequency Characteristics
Top: Elimination of Common Mode Noise, Pass-thru and Reflection Ratio
Middle: Sdd21 Differential Signal Pass-thru Amplitude Characteristics
Bottom: Scc21Common Mode Pass-thru Amplitude Characteristics

CDKF10R (Electro-magnetic Simulation)

Relative Power100%

Pass-thru

80%
60%

Elimination

40%
20%

Reflection

Magnitude[dB]

Magnitude[dB]0%0-1-2-3-4-5-6-7-8-9-100-5-10-15-20-25-30
051015Frequency[GHz]20

ELMEC Corporation

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9-2 Response waveform of Pseudo-Random Bit Sequence
Cable
Positive:2500ps
Negative

Positive

SignalTermination
source(Measurement
Negativepoint)
Skew

CDKF type-R
SPICE model (1)*Common-mode noise and Eye-pattern (SPICE simulation results in above circuit)
Top: Common-mode noise waveform
Middle: Common-mode noise spectrum
Bottom: Eye-pattern(A) 10Gbps Pseudo-Random Bit Sequence, Rise/Fall time (20%-80%): 20ps/20ps, Skew: 40ps
Negative Cable: 2470ps
Prior to CDKF type-R Connection
CDKF10R Connection(1)* The CDKF10R SPICE model is derived from electro-magnetic simulation.

ELMEC Corporation

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10. Tape and Reel specifications
In order to accommodate automatic mounting, we provide Tape & Reel packaging. The package isembossed with cover tape and contains 500pcs per reel, as shown below. The reel is marked with suppliername, part number, quantities, and lot number.
DIMENSIONS OF TAPE
Unit: mm(inch), Tolerance: ±0.1(0.004)
Materials: Polystyrene (Conductive), 0.4t(0.016t)
Direction of Feed
No 1 pin

Dimensions of Reel
Unit: mm(inch)
Materials ①Center: foam styrene, ②Sides: EF Cardboard①②ELMEC Corporation

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Technical Note 1: Frequency Characteristics of Common-Mode Impedance
For the CDKF type-R and the ideal common-mode choke coil (hereafter, ideal CMC), the frequency
characteristics of common-mode impedance are calculated with a circuit simulator and the difference isverified. The equivalent circuit and the main characteristics of the ideal CMC are shown in Fig. 1. Asmuch as possible, the －3dB passband was made wideband.
－3dB passband: 16.6GHz

Magnitude[dB]0-5-10

Sdd21-15-20

Scc21-25-30
051015Frequency[GHz]20Fig.1 Equivalent circuit and main characteristics of the ideal CMC
The method utilized for calculating commonmode impedance is shown below.
In general, common-mode impedance (Zcom)
Fig. 2, is generated by a common-mode choke coilfrom common-mode noise. That value can becalculated from this circuit. Conversely, because
the structure of the CDKF type-R absorbs andremoves the common-mode noise within theSignal Line-GND circuit, common-mode
impedance (Zcom) can be calculated from thecircuit arranged and shown in Fig. 3.
Fig. 4 shows the frequency characteristics of theideal CMC and CDKF type-R Common-mode
impedance from the calculation circuits inFigs. 2 and 3. Here, the ideal CMC uses a circuit
simulation S-parameter while the CDKF type-R
uses S-parameter derived by the electro-magnetic
simulation.

1000

Ideal CMC

Impedance [Ω]800)cZ(gam600

CDKF10R

400
20000510Frequency [GHz]15Fig.4 Frequency characteristics ofCommon-mode impedance

S-parameterFig.2 Generation chart and calculationcommon-mode choke coil Zcom

S-parameterFig.3 Generation chart and calculation circuit ofCDKF type-R Zcom

The ideal CMC intercepts the common-mode noise
by generating high impedance within the signal line.
As shown in Fig. 4, it appears to be effective in thevicinity of 2GHz. However, the inclination of thefrequency characteristics is quite steep.
Common-mode impedance is reduced as it diverges
from 2GHz, and the intercept function decreases.
On the other hand, the CDKF type-R is set to thevalue from the signal-GND circuit corresponding tothe common-mode impedance which is constant and20 small and has a fairly smooth frequency response.
There appears to be an advantage to being able tolower the dependency on the frequency and to do a
wideband absorptive removal of the common-mode
noise.

ELMEC Corporation