Pseudo-random Binary Sequence Generator Research Articles

An 80-Gb/s 2/sup 31/-1 pseudorandom binary sequence generator in SiGe BiCMOS technology

A 2/sup 31/-1 pseudorandom binary sequence (PRBS) generator with adjustable output data rates up to 80 Gb/s is reported in a production 130-nm BiCMOS process with 150-GHz f/sub T/ SiGe heterojunction bipolar transistor (HBT). The pseudorandom sequence is generated at 20 Gb/s using a linear feedback shift register (FSR), which is then multiplexed up to 80 Gb/s with a 4:1 multiplexer. A BiCMOS logic family combining MOSFETs and SiGe HBTs on high-speed paths is employed throughout the PRBS generator to maximize building block switching speed. Adjustable delay cells are inserted into critical clock paths to improve timing margins throughout the system. The PRBS generator consumes 9.8 W from a 3.3-V supply and can deliver an output voltage swing of up to 430 mV single-ended at 80 Gb/s.

Ultra-high speed all-optical shift registers and their applications in OTDM networks

All-optical shift registers are basic building modules for the development of ultra-high speed optical time division multiplexing networks. In this paper, we review the progress that has been made in this cutting-edge technology, focusing on implementations that exploit the attractive features of semiconductor optical amplifier (SOA)-based interferometric configurations. We present regenerative storage performed with an all-optical recirculating shift register with an inverter at 10 Gb/s using a SOA-assisted Sagnac switch and a second SOA to provide feedback. We demonstrate also an all-optical memory based on the SOA-assisted Ultrafast Nonlinear Interferometer capable of reading/writing 20 Gb/s packets of variable length without data inversion. These registers can find application in the development of two nontrivial complex all-optical circuits of enhanced functionality. The first is an all-optical pseudorandom binary sequence generator for which we describe an efficient design algorithm and propose ways for monitoring and verification. The second is an all-optical error counter for which we address the error detection and evaluation issues using a novel sampling technique. These circuits are key elements for the implementation of a high-speed, all-optical bit error rate tester (BERT), which has the potential to outperform its electronic equivalent and constitute a possible new product for the telecommunications industry.

Modulation and demodulation of 2 GHz pseudo random binary sequence using SFQ digital circuits

The high speed and low power needed for Spread Spectrum communications leads to a desirable application of digital superconductivity. Low temperature Nb/AlOx/Nb digital Single Flux Quantum (SFQ) circuits have been designed and fabricated in our facility, which compose critical subcircuits of the superconductive Spread Spectrum Modem. Four- and 6-bit Pseudo Random Binary Sequence (PRES) generators with output latching amplifiers have been produced and operated at up to 5.4 GHz. On chip modulation and de-modulation of these PRES codes have been performed with time resolution of less than one chip of the code. High-speed off-chip data was XORed with the on-chip PRES at up to 3.7 GHz to produce the modulated pattern. Rapid synchronization allows the code to start within one clock cycle of being fully reset, and the latching output amplifier gives enough power to do real time room temperature measurements of high-speed SFQ circuits.

A 10-Gb/s silicon bipolar IC for PRBS testing

A 10 Gb/s silicon bipolar IC for pseudorandom binary sequence (PRBS) testing was fabricated and tested. The IC features PRBS generation of the sequences of length 2/sup 15/-1 and 2/sup 23/-1 b up to 10 Gb/s according to CCITT recommendations. Furthermore, the IC is capable of analyzing PRB sequences of the same length and generation polynomials so that a full test of components is possible. In addition, a new PRBS test word synchronization can be provided between two chips for external multiplexing of the sequences up to 40 Gb/s. The IC can be connected to a standard PC, so evaluation of the error test data can be performed in a flexible way. The IC was fabricated with the HP25 process of Hewlett Packard company, the chip size is 32 mm/sup 2/, and it consumes 6.2 W at the nominal supply voltage of -5 V.

Silicon bipolar IC for PRBS testing generates adjustable bit rates up to 25 Gbit/s

For the first time, a completely integrated pseudo-random pattern generator providing adjustable bit rates up to at least 25 Gbit/s without additional external multiplexing is presented. The sequence length is 27 – 1. The application of the monolithic Si bipolar IC serves as a single chip measurement instrument for pseudo-random binary sequence (PRBS) generation required for the characterisation and development of high-speed components used in future optical fibre communication systems. Only three external microwave components are needed for operation: a clock generator, a power divider and a phase shifter. The chip is realised in an advanced implanted base silicon bipolar techhology.

An efficient method to determine linear feedback connections in shift registers that generate maximal length pseudo-random up and down binary sequences

Based upon the mathematical characterization of linear feedback shift registers, an efficient algorithm for designing a maximal length pseudorandom binary sequence generator is postulated. The proposed algorithm is not only computationally cost effective in relation to existing algorithms, but also yields the knowledge of feedback connections corresponding to the reciprocal of each nth order primitive polynomial itself. This makes the algorithm a further, more effective tool for an LFSR based testing of digital circuits.

Meteor Burst Channel Simulator

This paper describes the hardware implementation of meteor burst channel simulator using the reported data of meteoric burst channel parameters. The look-up table approach along with Pseudo Random Binary Sequence (PRBS) generator is adopted for simulation of the diurnal variation in the channel. The exponential decay for underdense and specular overdense meteors have been simulated. The simulated channel parameters are compared with the reported data of real meteoric burst channel.

PRBS generation and error detection above 10 Gb/s using a monolithic Si bipolar IC

This paper describes the application of a monolithic Si bipolar IC to serve as a single-chip measurement instrument for pseudo-random binary sequence (PRBS) generation, bit error detection, de-scrambling, and trigger derivation up to 12.5 Gb/s. The package interconnect problem of high I/O count multi-Gb/s IC's is addressed. The paper presents a packaging solution with improved ground contact and odd-mode controlled impedance differential microstrip transmission lines. A method for phase synchronization of multiple PRBS generators is proposed and its feasibility is demonstrated by measurement results. >

Intrinsic weakness of variable-memory keystream generators

A cryptographic weakness in a pseudorandom binary sequence generator proposed in the literature as a keystream generator for stream cipher applications is pointed out. Some results obtained by computer simulation are presented.

A spread-spectrum based synchronization technique for digital broadcast systems

A technique that has been verified experimentally to improve the synchronization efficiency of digital communication systems over present systems without sacrificing reliability is presented. This technique is called the spread-spectrum system pilot technique (SSPT). Incorporated into this technique are elements of tone-calibrated techniques (TCT) and spread-spectrum systems. In the SSPT system, the desired pilot tone is modulated by a pseudorandom binary sequence (PRBS) generator of finite duration and then linearly added to the source (customer) data that is actually being sent. At the receiver, the same finite PRBS sequence is used to decode the received signal. The system works because it provides an accurate version of the actual data carrier to be used in demodulation of the received signal. Based on the research presented, it is expected that this type of system will lead to better performance than currently used transparent-tone-in-band and other techniques used in multipath fading environments, which are especially problematic in mobile broadcast and communication applications. >

Algorithmic determination of linear-feedback in a shift register for pseudorandom binary sequence generation

Most methods for calculating the feedback connections in a shift register to generate pseudorandom sequences are based on obtaining the feedback characteristic polynomial. This polynomial must be irreducible modulo two, which means that the lower order irreducible polynomials must be known. With other solutions, such as those using cosets or those which use matrixes, the sequence to be generated must be known to determine the feedback connections to be used. In the paper, we establish a method for calculating the linear-feedback connections, in shift registers, to generate maximum-length pseudorandom sequences. The calculation of these feedback connections is independent both of other possible feedback and the sequence to be generated. The resulting algorithm has a short execution time, regardless of the length of the register used. The work establishes a condition on the feedback connections which is necessary and sufficient for a maximum-length sequence to be generated. No previous knowledge about other feedback of lower order or the sequence to be generated is required.

Design of counter registers

The paper describes a method of designing counter registers. Two important features of the method are that it produces a minimal design and that it is guaranteed to avoid jamming. The method may be applied to the synthesis of any counter registers used, for example, as binary-sequence generators, word generators, counters, pseudorandom binary-sequence generators etc. The paper contains examples which demonstrate the design procedure, and gives some results relating to minimal counter registers.

A Simple Technique for the Determination of Delayed Maximal Length Linear Binary Sequences

The problem of delayed sequence generation from a central pseudorandom binary sequence generator is considered. In particular a simple algorithm is derived which permits the convenient determination of delayed sequences.

Analysis and Digital Realization of a Pseudorandom Gaussian and Impulsive Noise Source

This paper presents results on the analysis and digital hardware realization of a non-Gaussian impulse noise source which can be used to model the impulsive noise present in wide-band communications systems. The impulse noise appearing in practical systems is characterized by bursts of much higher amplitudes than would be predicted by a normal- or Gaussian-distribution law. A need exists for a better characterization of this non-Gaussian impulsive noise as well as actual noise generators which can be used for evaluation of present and future communications equipment under realistic system-operating conditions. The impulse noise model and the realization of the noise generator described in this paper are capable of producing Gaussian background noise, lognormal impulsive noise, and burst timing to set prescribed starting and ending times of the bursts and impulse density within each of the burst periods. The techniques used in this paper are based on first generating a basic pseudorandom binary sequence (PRBS) and then from this deriving the Gaussian background noise by adding samples from the PRBS generator. The lognormal noise is then derived from the same sequence by using an incremental exponential generator. The burst timing signals which realize an approximate Poisson distribution are obtained by observing the occurrences of specific subsequences from the PRBS generator.

Transition-matrix construction for pseudorandom binary-sequence generators

A method is described for rapidly finding the elements of a matrix operator which shifts the state of a class of linear sequence generators through a specified time interval. The method is applied to the problem of generating pseudorandom binary sequences with specified time shifts.