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"Absorbs and eliminates GHz-Band Multipath Reflection waves and noise emissions"

Differential Signal Balancer/Common-mode Noise Absorber
CDLD-Type R-Suffix
Multipath Reflection Remover
CDLD-Type E-Suffix

Features
・New, Non-magnetic Common-Mode filter utilizing delay line operating at 4G~28Gbps.

・Restoring Eye Patterns closed due to multipath reflection using the Passive internal CTLE (Continuous Time Linear Equalizer) version. (Please See Technical Note 1)

・Prior Removal and elimination of common-mode noise prevents noise transmission. (Please See Technical Note 2)

・Differential signal inter-phase skew and uneven Rise/Fall are automatically adjusted, correcting balance. (Please See Technical Note 3)

[Application Examples]

・Semi-conductor test device (Gbps) with common-mode noise transmission problems. (Please See Technical Note 4)

・Optical transmission system with an electrical/optical conversion board and high-speed networking device for EMI measure, eye pattern improvement.

This product is a 0805 size multi-layered ceramic chip-type LTCC part and is RoHS-compliant. S-parameter files (Touchstone format) and SPICE models can be provided for each component.
Care and Handling of LTCC Products

10Gbps Multipath Reflection Removal Example

(Please See Technical Note 1)
12.5Gbps Unbalanced
Stray LC
28Gbps Unbalanced
Stray LC
Thru
Thru with
Decision Feedback Equalizer
(DFE)
6dB Attenuator with
DFE
CDLD06E (Left)
CDLD03E (Right)

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%
Insulation Resistance: DC50V, over 100MΩ
Durable Voltage: DC50V, 1 minute
Rated Current: 100mA
Rated Voltage: 5V
Operating Temperature Range: -40°C to +85°C
Storage Temperature Range: -40°C to +120°C
* Single-ended operation will not produce usable waveforms.


Multipath Reflection Remover
Part Number Transmission
Speed(1)*
Insertion Loss
(2)*
DC Insertion
Loss
(2)*
Output Rise
Time
(20%-80%)
Delay Time

CDLD03E(3)*

25G~28Gbps 2dB Typ.
(at 13GHz)
5.5dB Typ. 25ps Typ. 30ps Typ.

CDLD04E(4)*

16Gbps 2.5dB Typ.
(at 8GHz)
6.0dB Typ. 30ps Typ. 40ps Typ.

CDLD06E(3)*

10G~12.5Gbps 3dB Typ.
(at 6GHz)
6.0dB Typ. 35ps Typ. 60ps Typ.


Differential Signal Balancer/Common-mode Noise Absorber
Part Number Transmission
Speed(1)*
-3dB Passband
(2)*
Output Rise
Time
(20%-80%)
Delay Time DC
Resistance

CDLD07R(3)*

16G~28Gbps DC~20GHz Typ. 25ps Typ. 70ps Typ. 1.0ΩMax.

CDLD10R

8G~16Gbps DC~15GHz Typ. 30ps Typ. 100ps Typ. 1.5ΩMax.
CDLD15R 5G~12.5Gbps DC~12GHz Typ. 35ps Typ. 150ps Typ. 1.5ΩMax.
CDLD30R 4G~8Gbps DC~7.5GHz Typ. 45ps Typ. 300ps Typ. 2.5ΩMax.
(1)* When using the recommended Land Pattern.The case where the passing waveform of 1 unit interval becomes sine wave-like is included. (Please See Technical Note 7)
(2)* When using the recommended Land Pattern.

(3)* Samples available.
(4)* Under development.


[Jumper Features]
After attaching the pads to the printed circuit board, assuming the possibility that this component might not load properly, we have prepared the CDLD00R jumper between the pads.
The CDLD00R is utilized for a minimal time between the input and output terminals and has no effect on the reduction of common mode noise or differential signal balance.
Part Number -3dB Passband(5)* Output Rise Time
(20%-80%)
Delay Time DC Resistance

CDLD00R

DC~20GHz Min. 25ps Typ. 10ps Typ. 1.0ΩMax.
(5)* When using the recommended Land Pattern.


Package Dimensions & Pin Configuration(provisional)

Unit:mm(inch)
Tolerance:±0.2(±0.008)











CDLD00R
・No Direction mark
・No connection between 2pin and 5pin

Suggested Land Pattern

Unit:mm(inch)
Tolerance:±0.1(±0.004)

1. Specific Land Pattern
Example for Dielectric Layer


2. Available Common-mode Choke Coil (0504 size) with shareable Land Pattern
For differential balance improvement and common-mode noise elimination under 10Gbps, an inexpensive common-mode choke coil can even be used. However, considering unanticipated multipath reflection which could occur after production of the board, we recommend insertion of a land pattern which can also be used to mount this product. Below is an example of a land pattern which can also be used with an available 0504 size common-mode choke coil



w/ this product
w/ 0504 size component
Board measurements
 ・Thickness:0.2mm
 ・εr:3.1 


*Please inquire about other board requirements.
*0302 size change board is planned.

3.Quality comparison of Specific Land Pattern and Shareable Land Pattern
(Electromagnetic analysis with loaded CDLD00R.)
Sdd21 Differential Transmission Sdd11 Differential Reflection



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: 2x



Typical Applications

(1) ECL (-2V termination line used)  




(2) PECL




(3) LVPECL




(4) LVDS




(5) CML


[*] Signal GND potential, such as a power supply GND or a Vcc line.

Please be sure to connect the GND Termination. (Please See Notes)



Characteristics Examples

Pulse response waveform
Transient analysis based on actual S-parameter measurements
(Actual data only extends to 20GHz. Due to lack of band-width, S-parameter was used for the
electromagnetic field analysis at 28Gbps and 16Gbps.)
Skew of Input Pseudo-Random Bit Sequence: 0ps
CDLD07R
28Gbps
16Gbps
[X-axis: 10ps/div, Y-axis: 200mV/div] [X-axis: 20ps/div, Y-axis: 200mV/div]


CDLD10R
16Gbps
10Gbps
[X-axis: 20ps/div, Y-axis: 200mV/div] [X-axis: 20ps/div, Y-axis: 200mV/div]


CDLD15R
10Gbps
5Gbps
[X-axis: 20ps/div, Y-axis: 200mV/div] [X-axis: 50ps/div, Y-axis: 200mV/div]


CDLD30R
8Gbps
5Gbps
[X-axis: 50ps/div, Y-axis: 200mV/div] [X-axis: 50ps/div, Y-axis: 200mV/div]




Frequency Characteristics
CDLD03E (Actual Measurement)
Sdd21 Differential Transmission
Differential Group Delay
Scc21 Common-mode Transmission
Common-mode power ratio

CDLD04E (Electromagnetic Field Analysis)
Sdd21 Differential Transmission
Differential Group Delay
Scc21 Common-mode Transmission
Common-mode power ratio

CDLD06E (Actual Measurement )
Sdd21 Differential Transmission
Differential Group Delay
Scc21 Common-mode Transmission
Common-mode power ratio

CDLD07R (Actual Measurement)
Sdd21 Differential Transmission
Differential Group Delay
Scc21 Common-mode Transmission
Common-mode power ratio

CDLD10R (Actual Measurement)
Sdd21 Differential Transmission
Differential Group Delay
Scc21 Common-mode Transmission
Common-mode power ratio

CDLD15R (Actual Measurement)
Sdd21 Differential Transmission
Differential Group Delay
Scc21 Common-mode Transmission
Common-mode power ratio

CDLD30R (Actual Measurement)
Sdd21 Differential Transmission
Differential Group Delay
Scc21 Common-mode Transmission
Common-mode power ratio


Technical Note 1:
Example of Eye-Pattern Improvement/Multipath Reflection Removal

For transmission rates over 10Gbps, multipath reflection is generated from the capacitive load of IC’s ESD protection diode and pad which can cause deterioration of the eye pattern. Also, unintended unbalanced capacitive/inductive load should also be considered. Differential eye patterns connected with various capacitive/inductive loads are shown form a circuit simulation using the circuit shown below.

In spite of the capacitive/inductive load, it is possible to remove multipath reflection and improve a stable eye pattern with the CDLD type.


12.5Gbps/28Gbps Pseudo-Random Bit Sequence (PRBS)
12.5Gbps
Unbalanced
Stray LC
L1/C1 & L4/C4 :2nH/2pF
L2/C2 & L3/C3 :1nH/1pF
28Gbps Unbalanced
Stray LC
L1/C1 & L4/C4 : 0.75nH/0.75pF
L2/C2 & L3/C3 : 0.25nH/0.25pF
Thru (2)
(without DFE)
Thru (2)
with DFE
6dB Attenuator (2)
with DFE
CDLD06E (Left) (1)
CDLD03E (Right)(1)
(without DFE)

(1)* S-parameter from Actual Measurement
(2)* S-parameter from Circuit Simulator


Technical Note 2:
Example of Common-Mode Noise Elimination

For transmission speeds in excess of 10Gbps, even a minor skew will cause common-mode noise. Below is the circuit used to produce the common-mode noise wave form.
A CDLD-type is inserted directly after the IC, the GHz band common-mode noise is eliminated and transmission noise is prevented from returning to the original level.

(*) ESD Protection Diode etc.

(A) 28Gbps Pseudo-Random Bit Sequence, Skew:10ps, CL:0.5pF, Channel Length:30mm
Thru CDLD03E (1)* CDLD07R (1)*
Noise amplitude[X-axis:500ps/div,Y-axis:500mV/div]
Spectrum[X-axis:2GHz/div,Y-axis:10mV/div]

(B) 16Gbps Pseudo-Random Bit Sequence, Skew:20ps, CL:1.0pF, Channel Length:100mm
Thru CDLD04E (2)* CDLD10R (1)*
Noise amplitude[X-axis:500ps/div,Y-axis:500mV/div]
Spectrum[X-axis:2GHz/div,Y-axis:10mV/div]

(C) 10Gbps Pseudo-Random Bit Sequence, Skew:25ps, CL:1.5pF, Channel Length:100mm
Thru CDLD06E (1)* CDLD10R (1)*
Noise amplitude[X-axis:500ps/div,Y-axis:500mV/div]
Spectrum[X-axis:2GHz/div,Y-axis:10mV/div]

(1)* S-parameter Actual Measurement
(2)* S-parameter Electromagnetic Field Analysis


Technical Note 3:
Example of Differential Signal Balance Improvement

The wave form at the receiver will degrade due to skew or a connector GND discontinuity. The positive/negative differential signal wave forms of such a case are shown using the circuit below.
By using the CDLD with a passive internal CTLE, in addition to skew cancelation and improvement of the phase balance, it is also possible to cancel amplitude differences.

(*) ESD Protection Diode etc.

(A) 25Gbps Pseudo-Random Bit Sequence, Skew:10ps, CL:0.5pF, Channel Length:30mm
Thru CDLD03E(1)*
[X-axis:100ps/div, Y-axis:500mV/div]

(B) 16Gbps Pseudo-Random Bit Sequence, Skew:15ps, CL:1.0pF, Channel Length:100mm
Thru CDLD04E(2)*
[X-axis:200ps/div, Y-axis:500mV/div]

(C) 10Gbps Pseudo-Random Bit Sequence, Skew:25ps, CL:1.5pF, Channel Length:100mm
Thru CDLD06E(1)*
[X-axis:200ps/div, Y-axis:500mV/div]

(1)* S-parameter Actual Measurement
(2)* S-parameter Electromagnetic Field Analysis


Technical Note4:
Comparison of Common Mode Noise Input Reflection

For transmission speeds under 10Gbps, Common-mode Choke Coils are available; however, the reflection from the Common-mode Noise which is blocked by the Common-mode Choke Coil is quite large, the spike on the input wave form from the reflected Common-mode Noise will be superimposed. Using a comparator to compare the input and output wave forms, this superimposed noise can be quite detrimental. The positive/negative input wave forms of such a case are shown using the circuit below.
The CDLD-type’s ability to absorb the Common-mode Noise in the GHz band is quite high which prevents the superimposition of Common-mode Noise reflections on the input wave form.


(A) 10Gbps Pseudo-Random Bit Sequence, Skew:20ps
Common mode choke coil (1)* CDLD10R (2)*
[X-axis:200ps/div, Y-axis:500mV/div]

(B) 5Gbps Pseudo-Random Bit Sequence, Skew:30ps
Common mode choke coil (1)* CDLD30R (2)*
[X-axis:500ps/div, Y-axis:500mV/div]

(C) 2.5Gbps Pseudo-Random Bit Sequence (3)*, Skew:50ps
Common mode choke coil (1)* CDLD30R (2)*
[X-axis:1ns/div, Y-axis:500mV/div]

(1)* Equivalent circuit created by a circuit simulator.
(2)* S-parameter Actual Measurement.
(3)* CDLD30R corresponding transmission speed is 4G~8Gbps; however, when used to prevent Common Mode Noise reflection, depending on the frequency of the noise, effectiveness at lower transmission speeds is also shown.


Technical Note5:
Step Response Skew Improvement Example


Using a TDR Sampling Oscilloscope, we constructed and measured the test circuits shown below, positive/Negative(In(+)/In(-)/Out(+)/Out(-)), output common-mode noise(Comm)and the output differential signal(Diff)step response wave forms are shown. The CDLD-type, which contains a delay mechanism, delays the noise from the output waveform and avoids affecting the rise/fall edge.
Skew of signal source: 60ps

CDLD00R (Jumper)
(Edge)
[X-axis:500ps/Div]
[X-axis:100ps/Div]
In/Out/Comm[Y-axis:100mV/Div]
Diff[Y-axis:200mV/Div]

CDLD30R

(Edge)
[X-axis:500ps/Div]
[X-axis:100ps/Div]
In/Out/Comm[Y-axis:100mV/Div]
Diff[Y-axis:200mV/Div]


(C) Common-mode choke coil
(Edge)
[X-axis:500ps/Div]
[X-axis:100ps/Div]
In/Out/Comm[Y-axis:100mV/Div]
Diff[Y-axis:200mV/Div]



Technical Note 6:
Frequency Characteristics of Common-Mode Impedance

For the CDLD-type 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 is verified. The equivalent circuit and the main characteristics of the ideal CMC are shown in Fig. 1. As much as possible, the -3dB passband was made wideband.

3dB passband: 16.6GHz
Fig.1 Equivalent circuit and main characteristics o the ideal CMC

The method utilized for calculating common-mode 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 be calculated from this circuit. Conversely, because the structure of the CDLD-type absorbs and removes the common-mode noise within the Signal Line-GND circuit, common-mode impedance (Zcom) can be calculated from the circuit arranged and shown in Fig. 3.

Fig. 4 shows the frequency characteristics of the ideal CMC and CDLD30R Common-mode impedance from the calculation circuits in Figs. 2 and 3. Here, the ideal CMC uses a circuit simulation S-parameter while the CDLD30R uses an S-parameter measured with a 4-port network analyzer.

Fig.2 

Generation chart and calculation
common-mode choke coil Zcom
Fig.3 

Generation chart and calculation
circuit of CDLD type 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 the vicinity of 2GHz. However, the inclination of the frequency characteristics is quite steep. Common-mode impedance is reduced as it diverges from 2GHz, and the intercept function decreases.
On the other hand, the CDLD30R is set to the value from the signal-GND circuit corresponding to the common-mode impedance which is constant and small and has a fairly smooth frequency response. There appears to be an advantage to being able to lower the dependency on the frequency and to do a wideband absorptive removal of the common-mode noise.
Fig.4 Frequency characteristics of
     Common-mode impedancec










Technical Note 7:
CDLD Transmission Speed

The differential frequency characteristics (Sdd21) of a differential transmission line with a 30ps skew are shown in Fig. 1. In Fig. 1, a differential signal is intercepted to become a complete common mode signal at 16.7GHz because the 30ps skew makes a 180° phase shift at that frequency. Transmission of the differential signal forms an attenuation pole at 16.7GHz and the -3dB passband becomes DC to 8.3GHz.

-3dB Passband: DC~8.3GHz
Fig. 1 Differential frequency characteristics (Sdd21) of differential transmission line with 30ps Skew


0s Skew (-3dB Passband: DC~12.0GHz)
30ps Skew (-3dB Passband: DC~6.8GHz)
Fig.2 Differential frequency characteristics (Sdd21) with CDLD15R connected in the differential transmission line shown in above.

Next, the CDLD15R frequency characteristics of the differential input signal skew of 0s, 30ps are shown in Fig. 2.
In Fig. 2, compared to the -3dB passband of 0s skew, the -3dB passband of 30ps skew is greatly reduced. However, as clearly indicated in Fig. 1, the cause is not due to the effects of the CDLD15R; rather, it is determined by skew generated by the transmission line. That is, the quality of the differential output waveform probably does not depend on the CDLD -3dB passband. Rather, it depends on the value of the skew when the CDLD is connected for skew cancellation. It can be assumed to become like the sine wave to which the high-order harmonic is missed in 1Unit Interval corrugating according to the transmission speed. Especially at speeds of more than 10Gbps, the trend is more noticeable.
Therefore, the corresponding transmission speed of CDLD is not calculated simply from its -3dB passband, when the skew was generated, the maximum value at the correspondence transmission speed to which output waveform fineness was able to be maintained was examined on the assumption that passing waveform at 1Unit Interval became like the sine wave according to the characteristic of Fig. 1.
As a result, we judged that it was possible to correspond enough up to the transmission speed described in the specifications.
In addition, our CSKF-type not only cancels the skew but also restores the differential transmission signal. If the rough skew is canceled by the CSKF-type and the residual skew is canceled by the CDLD, it is possible to balance the differential signal completely.


RoHS Compliance Status

RoHS-compliant

Notes

Always connect the GND terminals. Using this product without connecting the GND could cause common mode noise rejection and delay line functions to deteriorate.
Use of only one line will not yield a normal wave form and cannot be used.




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