Repeaters and retimers maintain high signal quality
Signal-Integrity
By further developing system interconnect technologies from parallel bus systems to serial methods, transmitting speeds on the electrical level increased rapidly beyond the gigahertz threshold. Despite differential transmission and power source transmitters, the traces on FR4 base materials via plug-and-socket connectors, solder points or even cable lines resulted in significant distortions and damping, in particular where extended transmission ranges had to be bridged.
So-called signal integrity products, i.e. signal conditioners, are designed to remedy this problem, as they are able to filter the original signals from background noise. IDT offers these amazing SIP components for all established transmission standards.
Signal Integrity - Retimer und Repeater
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Signal Integrity
On their path across the circuit board, high speed signals of current serial standards are easily affected by damping, reflection and distortion. This becomes apparent when looking at the so-called “eye diagram”, which provides a fairly clear measure for the quality of such signals. As shown in fig. 1, the “eye” of a signal can all but close due to these effects, which means technical measures are required for reconditioning. One way of achieving this is to optimize the transmission path, i.e. by coherently implementing microstrip technology on circuit boards and minimizing the number of connectors. However, this strategy is very difficult to consistently apply in practice, which means that electronic signal reconditioning often remains the only realistic alternative.
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The semiconductor manufacturer IDT has developed a range of repeater & retimer components for this purpose, offering solutions for the most common transmission standards.
Repeaters and retimers differ in their complexity and the resulting conditioning options: while repeaters generally consist of an input equalizer and an output booster, thus reducing random jitter, retimers dispose of resources for interpreting signals and are thus able to eliminate deterministic jitter as well.
Retimers are therefore protocol specific and also add noticeable latency to the transmission range, in the case of IDT’s PCIe retimers, for instance, in the range of 30ns.
IDT Repeaters
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Repeater components of the IDT SIP portfolio are available for 5 Gbps PCI Express® (PCIe) Gen2, USB 3.0, 6 Gbps SAS/SATA; 6.25Gbps Serial RapidIO® 2.1 and other standards for computing, storage & communication applications.
SIP components comprise powerful receiver equalizers and transmit-de-emphasis amplifiers as well as diagnostic functions, allowing simple designs and fast development cycles.
They are able to drive long circuit paths on PCBs (e.g. on backplanes) and to secure cable lines to external devices, guaranteeing optimal system performance. They are also able to recognize signal interruptions (LOS - loss of signal) and provide individual loopback diagnostics for each channel and 2:1 multiplexing & de-multiplexing functions.
These components are available for 2, 4 or 8 differential channels and can be configured via I2C, control pins or EEPROMs. They also offer power saving operation modes in order to reduce power consumption.
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IDT Repeater Product Brief:
- IDT 89HP0504P 4 Channel 5Gbps PCIe Signal Repeater
- IDT 89HP0504PB 4 Channel 5Gbps PCIe Signal Repeater
- IDT 89HP0504U 4 Channel 5Gbps USB3.0 Signal Repeater
- IDT 89HP0508P 8 Channel 5Gbps PCIe Signal Repeater
- IDT 89HP0604R 4 Channel 6.25Gbps Serial Rapid IO Signal Repeater
- IDT 89HP0604S 4 Channel 6Gbps SAS SATA Signal Repeater
- IDT 89HP0608R 8 Channel 6.25Gbps Serial Rapid IO Signal Repeater
- IDT 89HP0608X 8 Channel 6.25Gbps XAUI Signal Repeater
Repeater Features
- Compensates for cable and PCB trace attenuationand Inter-Symbol-Interference-Jitter (ISI)
- Programmable Rx-Equalizer up to 30db
- Programmable De-Emphase up to -8.5dB
- Recovers data stream even when differentialsignal eye is completely closed dur to traceattenuation and ISI Jitter
- Full PCIe protocol support
- SAS/SATA, Out of Board (OOB) Support
- Configurable via external pins, while extendedprogramming ranges are available via I2Cinterface
- Supports automatic download of configurationfrom external EEPROM with a single or multiplerepeaters on I2C bus
- Power minimization in active and shutdown mode
- No external bias resistors or reference clocksrequired
- Channel mux mode, demux mode, 1 to 2channels multicast, and Z-switch function modeRepeater
Benefits
- Extends maximum cable length to over 10 metersand trace length over 65 inches in PCIeapplications
- Speeds up system design by allowing usage oflonger trace and cable length
- Minimizes bit error rate (BER)
IDT Retimer
IDT retimers were developed with the goal to improve signal integrity while at the same time doubling the transmission range. They minimize random & deterministic jitter of input signals and are thus perfectly suited for blade servers, enterprise storage or communication systems which require longer cable lines or backplane traces.
The most recent additions to the extensive product range are the 89HT0808P and 89HT0816P retimers. They are the first of their kind to fully support the new PCIe automatic link equalization process, simplifying system design and improving reliability of PCIe compliant adapter cards or host bus adapters.
The 8 channel 89HT0808P retimer and the 16 channel 89HT0816P retimer are able to provide data communication rates of 8 Gbps per channel across twice the range as standard PCIe 3.0 devices and via typical system backplanes, at the same time improving system performance and reliability and reducing material costs, since the overall design complexity is reduced.
Both retimers comprise a very powerful analogue frontend and are linked to a continuous time linear equalizer (CTLE), a five-level decision feedback equalizer (DFE) and a clock & data recovery unit.
The very sensitive input offers dynamic optimization options and is able to restore low quality signals and to eliminate randomized and deterministic jitter, exceeding the thresholds of the PCIe 3.0 specification. In order to enable rapid in-system testing, an extensive suite of diagnostic loopback characteristics was integrated in IDT's retimer monitoring functions. An evaluation board is available for IDT's 89HT0808P and 89HT0816P retimers, together with a software utility with a graphic user interface.
IDT's extensive signal integrity product range comprises solutions for industry standard interfaces such as PCIe Gen 2 and Gen 3, USB 3, XAUI, SATA, SAS and Serial RapidIO® and is available in a variety of channel numbers and casing sizes.
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Retimer Features
High Performance
- Minimizes random input jitter
- Minimizes deterministic ISI jitter
- Compensates for channel attenuations
- Tunable Rx and Tx performance and power
- Up to 8dB of transmit deemphasis
- Programmable multi-stage equalizer
- CTLE and 5-tap DFE
- Fast aquisition PLL for L0s exit
- On-Chip SERDES eye scope
SerDes Power Savings
- Supports low swing operation
- Auto low power for unused lanes
- PCIe Standards and Compatability
- PCIe Base-Specification 3.0 compliant
- PCIe Base-Specification 2.1 compliant
Hot Plug Support
- Link Configurability
- Configurable to 1x8, 1x4, 1x1, 2x4, 2x1
- Automatic per port link width negotiation
- Per-lane SerDes configuration:
- De-Emphase, Equalization, Drive
- Clocking Standard 100 MHz PCIe Reference clock
- SSCLK (Spread Spectrum) and non-SSCLK
- Reliability, Availability and Serviceability (RAS)
- Physical-Layer error checking and accounting
- End-to-End Datapath Parity-Protection Checksum
Test and Debug
- Per link/lane error diagnostic registers
- All registers acessible from I2C or JTAG
- SerDes test modes
- Several loopback modes
