SHF Communication Technologies AG
Wilhelm-von-Siemens-Str. 23D • 12277 Berlin • Germany
Phone +49 30 772051-0 • Fax +49 30 7531078
E-Mail: sales@shf.de • Web: http://www.shf.deDatasheet
SHF 78212 A
Synthesized Clock Generator

SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Description
The Synthesized Clock Generator SHF 78212 A is designed to provide our BERT system customers witha suitable internal clock source at reasonable cost. It is a field replaceable plug-in module which needs tobe installed in an SHF mainframe. Together with other plug-in modules from this instruments series, amodular and scalable measurement system can be put together.
It features a wide frequency range from 0.625 to 67 GHz with a 1 kHz resolution and a large outputpower (typically 8 dBm up to 60 GHz and 3 dBm up to 67 GHz). The output power can be adjusted in0.1 dB steps.
The clock source generates clock signals with low jitter and low phase noise. For frequencies above
10 GHz, additional band-pass filtering ensures low harmonic levels. Below 10 GHz, short rise time clock
signals are generated resulting in an increased level of higher-order harmonics.
The jitter injection functionality is integrated for jitter stress test applications. Arbitrary jitter types may be
applied to the clock signal by connecting an external signal source to the modulation input, enabling
various test scenarios such as compliance testing.
An additional trigger output provides a trigger signal whose frequency can be switched to a quarter(CLK/4 mode) or half the output frequency (CLK/2 mode). Above 40 GHz, the trigger is limited to CLK/4mode.

Block Diagram
Jitter Injection ON/OFFModulation InfCLK
Synthesizer
Module10 MHz Ref Out
10 MHz Ref In

RF OutfCLK = 0.625 to 67 GHz

Jitter Injection
ModulefCLK /NTrigger OutFeatures
Output clock frequency ranges from fCLK = 0.625 to 67 GHz with 1 kHz resolution



Output power adjustable with 0.1 dB resolution from –10 to +8 dBm

External jitter injection using an external signal source such as SHF 19120 AWG

Supports three spread-spectrum clocking (SSC) modes

10 MHz reference input and output for phase locking to other instrumentsRemote programming interface (Ethernet, USB) for automated measurements

SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Ease of Use
The SHF 78212 A is operated inside an SHF mainframe and controlled by an external computer. Everysystem comes along with the intuitive, easy to use SHF Control Center. It provides the interface forchanging the device parameters.
Additionally, the instrument may be programmed remotely over the Ethernet connection for automatedtests and measurements. Please refer to the SHF BERT Programming Manual.
Note that SHF also offers the compact standalone Synthesized Clock Generator SHF 78122 B. Please
visit www.shf.de for further details.

SHF Control Center window for the SHF 78212 A

SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Specifications
Parameter

SymbolUnitMin.

Typ.

Max.

CommentfCLK

GHz

0.625

Frequency Resolution

kHz1

Frequency Accuracy

ppb

–1000

+1000

Using internal reference

Frequency Stability

ppb

–50

+50

Ambient
temperature 21°C

Frequency Stability Agingppb–500+500

per year

Clock Output (RF Out)Operating Frequency

67–10

Minimum Output PowerPout,mindBm

Maximum Output PowerPout,maxdBm

863

Output Power Resolution

dB

0.1

Output Power AccuracydB–1

fCLK ≤ 38 GHz
fCLK ≤ 62 GHz
fCLK ≤ 67 GHz

841Output Power Temperature
Drift

dB/°C

0.1

Harmonic Signals

dBc

–20

Phase Noise

Jitter (RMS)

JRMS

fs400

ΩOutput Impedance

For fCLK ≥ 10 GHz;
On scope display (notdeconvolved)

50Connector
Parameter

For fCLK ≥ 10 GHz
fCLK = 10 GHz
1 kHz offset
10 kHz offset
100 kHz offset
1 MHz offset–90–92–85–109

dBc/HzAmbient
temperature 21°C

1.85 mm (V) male
Symbol

Unit

Min.

Typ.

Max.

Frequency

GHz0.15625

21

Output Amplitude

mVpp

400

1000

Output ImpedanceΩCommentTrigger OutConnector

50
SMA female

SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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External Jitter Injection
Modulation Frequency

MHz

0.5

1000

Modulation Amplitude

mVpp

01200

Jitter Amplitude

ps050

Input ImpedanceΩPeak-to-peak

50

Connector

SMA female

Spread Spectrum Clocking
Modulation Frequency

Hz10100 kDeviation

ppm

020,000

Up/down/center

10 MHz Ref Input
Reference Frequency

frefMHz

Amplitude

Vpp

Input Impedance

Ω100.23.350Connector

SMA female

10 MHz Ref Output (using internal reference setting)1

Reference Frequency

MHz

10

Amplitude

Vpp

Output ImpedanceΩFrequency Accuracy

ppb

–250

250

Frequency Stability

ppb–50+50

Ambient
temperature 21°C

Frequency Stability Aging

ppb

–300

+300

per year0.850Connector

SMA female

GeneralPower Consumption

WWeightkg

Operating Temperature°C

25

Power supplied by SHF
Mainframe

35

Ambient temperature4101The specifications in this datasheet are only valid if the internal reference is activated. If the externalreference setting is activated the signal at Ref In is fed through to Ref Out. In this case the parameters
frequency, stability and amplitude depend on the Ref In signal.
SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Typical Output Waveforms

16 GHz clock output at 4 dBm

20 GHz clock output at 4 dBm

32 GHz clock output at 4 dBm

40 GHz clock output at 4 dBm

56 GHz clock output at 4 dBm

64 GHz clock output at 4 dBm

Note that for clock frequencies above 10 GHz, the signal is band-pass filtered to achieve low harmonics
and a nearly pure sinusoid. Below 10 GHz, however, the clock signals are amplified with subsequent
amplitude clipping to shorten the rise time. In the frequency range below 10 GHz, this generates
noticeable higher-order harmonics. The SHF 78212 A is optimized for clock source applications incombination with SHF BERT instruments, where a short rise time is preferred.

SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Output Amplitude
The output amplitude can be varied from -10 to +8 dBm. By default, the amplitude is software-limited to+4 dBm to prevent damage on connected devices. If required the instrument can be configured to set theamplitude to the available hardware maximum. The typical hardware maximum is +8 dBm up to 62 GHz
and +4 dBm up to 67 GHz. The amplitude can be set in 0.1 dB steps.
For clock frequencies above 10 GHz, the amplitude value in dBm, 𝑃𝑑𝐵𝑚 , can be converted from and to 𝑉𝑝𝑝using the following equations which are valid in a 50 Ω system:

𝑃𝑑𝐵𝑚 = 20 log10 (𝑉𝑝𝑝 ) + 4(Eq. 1)

𝑉𝑝𝑝 = 10(𝑃𝑑𝐵𝑚−4)/20.

(Eq. 2)

Note that below 10 GHz, the measured 𝑉𝑝𝑝 will be slightly smaller than the value calculated from (Eq. 2)
since the clock signals in that frequency range contain higher order harmonics rather than being a singletone sinusoid.

External Jitter Injection
For additional flexibility, arbitrary jitter modulation may be applied to the high-speed clock signal. Jitter isinjected by connecting a signal source such as an arbitrary waveform generator to the external modulation
input. The maximum jitter amplitude is 50 ps peak-to-peak with a modulation bandwidth of up to 1 GHz. As
an example, the jitter amplitude of 50 ps corresponds to a relative jitter amplitude of 1.6 unit intervals (UI)
at a bit rate of 32 Gbit/s.
The jitter amplitude needs to be calibrated by the user.
In combination with an SHF Bit Pattern Generator and an Error Analyzer, the SHF 78212 A enables a test
solution for jitter tolerance tests as required by many telecommunication standards such as 100G Ethernet
and 40 GBit/s OTN, FibreChannel, InfiniBand, PCI Express®, and Serial ATA. For further details pleaserefer to the SHF application note „Jitter Injection using the Multi- Channel BPG“, available online atwww.shf.de.

Typical Jittered Signal Waveforms
The external modulation input can be driven by a function generator such as the SHF 19120 Arbitrary
Waveform Generators (AWG). The waveform characteristics of the AWG determine the jitter type.

 InfiniBand is a registered trademark of the InfiniBand Trade Association. PCI Express is a registeredtrademark of Peripheral Component Interconnect Special Interest Group (PCI-SIG).
SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Sine Wave on Modulation Input
SHF 78212 A

AWG Setting
Waveform

Sinusoidal jitter on 28 GHz clock.
Sine wave

Gaussian-Distributed Noise on Modulation Input
SHF 78212 A

Random jitter on 28 GHz clock.
AWG Setting
Waveform:NoiseSquare Waveform on Modulation Input
SHF 78212 A

Peak-to-peak jitter on 28 GHz clock.
AWG Setting
Waveform:

SquareSHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Spread Spectrum Clocking
To meet the regulatory demands of electromagnetic interference several high-speed bus systems use aspread spectrum clocking (SSC) method. When SSC is enabled, the instantaneous frequency of the clock
signal varies periodically with time by a small amount, i.e. the clock signal is frequency-modulated. Thefigure below illustrates the SSC frequency modulation with a triangular shape.
InstantaneousFrequency

Frequency
Deviation

Time1/Modulation Frequency

The principle of SSC is the periodic frequency modulation of a clock signal.

The key SSC parameters are the following:
fCLK

original clock frequency without SSC

δrelative frequency deviation (often given in percent or ppm, parts per million)

fjittermodulation frequency.

The parameters are directly accessible in the BERT Control Center software GUI or through remote
programming.
Depending on the relative position of the clock frequency and the frequency deviation, SSC can beclassified into three types: down, center, and up-spread. The figure below illustrates the three
configurations.

Down-Spread

Center-Spread

Up-Spread(1+δ) fCLK

Frequency(1+δ/2) fCLK
fCLK

fCLK

fCLK

(1–δ/2) fCLK

(1–δ) fCLK
1/fjitterTime

1/fjitter

TimeTime

1/fjitterThree types of SSC.

SSC, effectively, broadens the spectral peak of a clock signal so that the maximum of the power spectral
density is reduced leading to less radiated emission. This is illustrated in the following spectra measured atthe output of the SHF 78212 A for a 25 GHz clock with 30 kHz modulation frequency and 0.5% deviation.
Note that SSC does not reduce the total signal power of the clock. Rather, it redistributes the clock’s spectral
components as shown in the figure below.
SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Without SSC

With SSC

Peak Reduction

SpectralBroadening

SHF 78212 A clock spectrum with and without SSC.

SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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Mechanical Drawing

25.0

30.0

30.0
3 x 30.0

All dimensions are specified in millimeters (mm).

Input Connectors
Connector Name

Description

10 MHz Ref

External 10 MHz reference input

Modulation

External jitter modulation input

Output Connectors
Connector Name

Description

Trigger

Trigger output

RFClock output

10 MHz Ref

10 MHz reference output

SHF reserves the right to change specifications and design without notice – SHF 78212 A - V002 – Apr 24, 2018

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