SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 1/8

SHF BERT & DAC for NRZ, PAM4 and

Arbitrary Waveform Generation

Content

SHF’s “one for all“ System 2

(a) 64 or 120 Gbps binary “NRZ” BERT 2 (b) 60 GSymbols/s AWG 3 (c) 60 & 128 GBaud Generator and 58 GBaud PAM4 Analyzer (PAM4-BERT) 5

Compact BERT Series 8

SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 2/8

SHF’s “one for all“ System SHF has always been pioneering the market for high speed bit pattern generators (BPGs or PPGs) and error analyzers (EAs). Now, with PAM4 being the main stream of interest, SHF is continuing to push the limits with its flexible remote head approach for

(a) 64 or 120 Gbps binary (NRZ) bit error ratio testing or

(b) 60 GSymbols/s arbitrary waveform generation or

(c) 60 or 128 GBaud PAM4 signal generation and 58 GBaud PAM4 error ratio testing.

(a) 64 or 120 Gbps binary “NRZ” BERT

The key instruments for very high speed BER testing, the SHF 12104 A / 12105 A Bit Pattern Generator (BPG) and the SHF 11104 A Error Analyzer (EA), can be configured in a variety of different channel configurations with a maximum capacity of 512 Gbps per instrument.

Available for SHF 12104 A BPG & SHF 11104 A EA

Aggregated Data Rate 64 66 128 130 132 194 196 256 260 264 384 512

No. of 64 Gbps Channels 1 2 1 2 1 4 2 6 8

+ + + +

No. of 33 Gbps Channels 2 2 4 2 4 4 8

Available for SHF 12105 A BPG

Key Features SHF BPG

All channels are independent (i.e. programmable as it would virtually be a single BPG)

Synchronized channels for phase and bit alignment (inter-channel bit-delay or skew can be set individually)

Optional 2 V output amplitude (option HV)

Extensive user pattern memory per channel in addition to the ITU / CCITT PRBS patterns

Automation with external software possible (e.g. LabView, VEE, C or Python)

Up to 120 Gbps with the remote head Multiplexer (MUX) SHF C603 A

High quality output waveforms:

650 mV @ 64 Gbps 2 V @ 64 Gbps (Option HV) 120 Gbps

Key Features SHF EA

Individual auto search of optimum sampling point for each channel

Quick and powerful measurement routines e.g. for auto-search, Q-factor, jitter, eye contour

Up to 120 Gbps with the remote head Demultiplexer (DeMux) SHF C623 A

SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 3/8

(b) 60 GSymbols/s AWG

Combining a BPG with SHF’s digital to analog converters (DACs) turns the system into a multi-channel and multi-level source. With our SHF 12104/5 A BPGs one has full control of the patterns into the DAC (due to the huge memory and the channel synchronization). Therefore, our BPG-DAC combination is a remote head non-interleaved 60 GBaud Arbitrary Waveform Generator (AWG).

SHF 12105 A BPG with remote head DAC modules

Key Features Remote Head AWG

Sample rate = output baud rate

8 GSa waveform memory (in case a SHF 12105 A is used); 1 GSa waveform memory (in case a SHF 12104 A is used)

Remote head to preserve signal integrity close to the DUT

Speed, vertical resolution and output power depending on the used SHF DACs:

SHF DAC Max.

Baud Rate Max.

Vertical Resolution Max.

Output Amplitude @ Full Scale1

SHF 611 F 32 GBaud 3 bit (8 level) 0.8 V (se) 1.6 V (diff.)

SHF 612 A 32 GBaud 4 bit (16 level) 0.65 V (se) 1.3 V (diff.)

SHF 613 A 60 GBaud 3 bit (8 level) 0.65 V (se) 1.3 V (diff.)

SHF 614 C 60 GBaud 6 bit (64 level) 1.4 V (se) 2.8 V (diff.)

SHF 615 B 60 GBaud 3 bit (8 level) 2.4 V (se) 4.8 V (diff.)

Typical Performance Remote Head AWG (BPG + DAC)

PAM-4 @ 60 GBaud

PAM-8 @ 60 GBaud

Arbitrary Signal w. 60 GSa/s

Unequal PAM

Odd PAM (here PAM-5)

PAM w. Pre-Emphasis

1 Full scale: all input bits active, se: single-ended, diff: differential

SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 4/8

Software Package with AWG Features

A SHF BPG and a SHF DAC are not just two discrete modules connected together. The new complementary software package, the SHF Control Center (SCC), creates the patterns for any signal trace. As for a conventional AWG, there are various options to create the waveform:

Load it from a file

Select from our library & change the parameters (a PAM4 example is shown below)

Use the graphical sequence editor

Program your waveform in our editor (Python based programming)

DAC GUI of the SCC with the PAM4 library loaded

Parameters, like the amplitude of the individual levels, the pre-emphasis etc. can

be adjusted.

The SCC just needs to know which BPG output is connected to which DAC input and

an AWG is created.

SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 5/8

(c) 60 & 128 GBaud Generator and 58 GBaud PAM4 Analyzer (PAM4-BERT)

PAM4 Generator

For binary data a BPG has obvious advantages over an AWG as the bit/baud rate always equals the sample rate (no fractional oversampling) and as logical pattern generation techniques can be applied without utilizing a rather slow and small memory.

In first place one may think that these advantages do only apply to a pure BPG and not to an AWG based on a BPG/DAC architecture. For most microwave signals this is correct, however, for data signals the coding can be done in the BPG hardware, thus the user memory is not used and above advantages do still apply for the signals from the DAC.

Most prominently this applies to PAM signals. With the SHF 614 C 6-Bit DAC even the individual eye heights or pre-emphasis can be achieved and adjusted as outlined above for an AWG but on the fly without waiting for the memory to be loaded and by still transmitting very long patterns (e.g. PRBS 2

31-1 or PRBS31Q).

BPG GUI of the SCC for the logical PAM signal generation

SHF’s active DAC approach is more versatile, robust and supports more levels compared to simple passive combining. Further, it is faster than any other AWG instrument as it samples only one single time per each bit. Thus, the baud rate of the resulting PAM signal is as fast as the sample rate of the system. No other AWG can create high PAM signals of equal signal quality.

The speed advantage of the SHF system can be seen most prominently at the output signal of the SHF 616 A PAM4-MUX which supports data rates up to 128 GBaud (256 Gbps).

100 GBaud (200 Gbps)

from a SHF 616 B PAM4-MUX

112 GBaud (224 Gbps)

from a SHF 616 B PAM4-MUX

No issues with long patterns (e.g. PRBS

231

-1) as the pre-coding is done in hardware!

Individual eye heights can be set without

utilizing the memory.

Pre-Emphasis (FIR Filter) can be set without

utilizing the memory.

SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 6/8

PAM4 Analyzer

The SHF 11104 A Error Analyzer (EA) introduced above is capable not only to perform BER measurements at binary but also at PAM4 signals via the “3-pass” approach.

With this approach, the instrument is performing an auto-search to determine the optimum threshold values of the three individual PAM4 eyes, then successively samples all three eye openings of the 4-level signal, one at a time, and measures the three individual bit error ratios. After completion of this 3-pass measurement the software calculates the total bit error ratio (BER).

BCC SHF 11104 A EA GUI, showing the eye contours and error ratios of a 53 GBaud PAM4 signal

The SHF 11104 A Error Analyzer as a single instrument is capable to perform this measurement for PAM4 signals up to 32 GBaud. Extended with the SHF 11220 A PAM4 Sampler, the upper baud rate limit is raised to 58 GBaud (116 Gbps).

The SHF 11220 A PAM4 Sampler

In the PAM4 Sampler GUI, the built-in eye scan function has the capability to visualize an eye pattern of the input PAM4 signal, as well as executing a fast auto-search to determine the threshold values and delay of the input signal.

BCC SHF 11220 A PAM Sampler GUI, showing the eye scan of a 53 GBaud PAM4 signal

SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 7/8

Adaptive Equalization

The SHF 11104 A EA and the SHF 11220 A PAM4-Sampler combination offers excellent sensitivity to enable BER measurements of signals even with small eye openings. In a majority of test and measurements, however, the transmission path or the device under test (DUT) can introduce significant signal distortion and eye closure, rendering BER measurements impossible. The newly introduced SHF C681 A analog FIR equalizer module is intended to overcome this commonly encountered measurement problem. True error measurement even of heavily degraded signals is possible using the SHF C681 A 6-tap finite impulse response (FIR) filter, as illustrated below.

On the left hand side the illustration below shows a 53 GBaud PAM4 signal after transmission. This signal is severely degraded, eye closure in particular, making BER measurements impossible. After equalization, the signal eyes are opened up and freedom from errors (< 10

-11) is verified.

The equalizing effect at a 53 GBaud PAM4 signal

In addition to the factory generated pre-settings of some common universal loss values, all six equalizer tabs are accessible through the complementary software package. Further, a dedicated DSP program “SHF-FIR” can calculate the tap values for optimum equalization. Sophisticated transfer functions can be compensated; not just simple approximations.

DSP program “SHF FIR”

The filter module is not built into the error analyzer. This way it can be used as a “remote head” and placed wherever the equalization has the strongest effect (to generate pre-emphasis at the transmit site, to open small eyes after transmission, close to a DUT in a transmission chain or wherever needed).

Eye contour @ BER = 10-4

BER < 10-11

in optimum

SHF reserves the right to change specifications and design without notice – SHF BERT – V020 – January 2020 Page 8/8

Compact BERT Series The compact BPG series is SHF’s approach of delivering a high performance signal generation solution to the cost-sensitive datacom industry. The minimal power consumption and the light weight make it perfectly suited for on-wafer tests.

To date, the SHF 12124 A offered the lowest cost per bit rate of all bit pattern generators. Its successor, the SHF 12124 B, is now even offering pattern-synchronized channels to enable the generation of true PRBS at even higher speeds via a multiplexer or a DAC. Incorporating such a multiplexer or DAC in the BPG instrument results in our all new SHF 12125 B and SHF 12126 A, respectively.

SHF 12124 B SHF 12125 B SHF 12126 A

32

Gb

ps

bin

ary

2 differential

2 single-ended

2 single-ended

64

Gb

ps

bin

ary

--- 1

differential ---

32

GB

au

d

PA

M4

--- --- 1

differential

Key Features Compact BERT Series

Gap-free operation from 7 Gbps (GBaud) to the upper data & baud rate limit

4-Tap-FIR for pre-emphasis and skew control over two UI for 32 Gbps NRZ outputs

PRBS 27-1, 2

11-1, 2

15-1, 2

23-1, 2

31-1

Various clock and trigger outputs