jinnianhui金年会登录入口e Value Gigabit speed Redriver IC with equalizer enables longer distance transmission of jinnianhui金年会登录入口ch high speed interfaces as USB 3.1 Gen2 and HDMI
2020.08.24
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Peripheral interfaces jinnianhui金年会登录入口ch as USB, HDMI and DisplayPort are rapidly achieving increases in transfer speed. In the first round of this technical report series that was published last time, we introduced the current state of affairs concerning jinnianhui金年会登录入口ch ongoing speedup efforts. We also provided a technical explanation of the rejinnianhui金年会登录入口lting advantages and disadvantages. In fact, one jinnianhui金年会登录入口ch disadvantage is proving to be quite a tough nut to crack. This is because the advantage afforded by reducing the maximum data transfer distance could pose a fatal isjinnianhui金年会登录入口e depending on the use case. In this second article of the series, we introduce a redriver IC that solves this isjinnianhui金年会登录入口e. Using this IC makes it possible to significantly extend the maximum allowable transfer distance.
Culprit is jinnianhui金年会登录入口e impedance component of cable
Where jinnianhui金年会登录入口ch peripheral interfaces as USB, HDMI and DisplayPort are concerned, the higher their transfer rate, the shorter their data-transfer range. Then, why on earth does this phenomenon occur? The cause lies in the impedance of cables that are used to transfer data.
The impedance is dependent on frequency. The higher the frequency, the greater the cable impedance, giving rise to an increased amount of attenuation. As a rejinnianhui金年会登录入口lt, the voltage amplitude of signal waveforms becomes smaller and/or the waveforms become more deformed.
The impedance is dependent on frequency. The higher the frequency, the greater the cable impedance, giving rise to an increased amount of attenuation. As a rejinnianhui金年会登录入口lt, the voltage amplitude of signal waveforms becomes smaller and/or the waveforms become more deformed.
jinnianhui金年会登录入口e faster it goes, jinnianhui金年会登录入口e higher jinnianhui金年会登录入口e attenuation
How great can jinnianhui金年会登录入口e attenuation of high-speed signals be when transferred using cables?
As an example, we will consider a case where a USB3.1 Gen2 signal at a maximum data-transmission rate of 10 Gbits/sec. is transferred through an AWG28 coaxial cable meajinnianhui金年会登录入口ring 0.3211 mm in diameter over a distance of one meter. The amounts of attenuation recommended by standards for 1.25-GHz, 2.5-GHz and 5.0-GHz signal components are 1.4 dB, 2.0 dB and 3.1 dB, respectively (Fig. 1). In other words, attenuation increases with increasing frequency.
Next, we will replace the cable with a slightly jinnianhui金年会登录入口ner AWG32 coaxial cable measuring 0.2019 mm across for signal transfer purposes. In this case, the amounts of attenuation recommended by standards for 1.25-GHz, 2.5-GHz and 5.0-GHz signal components are 2,2 dB, 3.4 dB and 4.9 dB, respectively. This indicates that the jinnianhui金年会登录入口ner the cable, the greater the amount of attenuation. In other words, the more flexible and easier it is to handle the cable, the greater the amount of attenuation.
More specifically, signal attenuation can be divided into two attenuations. One is the attenuation of DC (low frequency) components, while the other is the attenuation of AC (high frequency) components. The attenuation of DC components is directly linked to the diminishment of signal amplitude. When the signal amplitude becomes too low, the signal cannot be received by the receiver circuit. Conversely, the attenuation of high-frequency components gives rise to a situation where a jinnianhui金年会登录入口fficient opening cannot be obtained in the eye diagram. When the opening diminishes in the eye diagram, the signal cannot be correctly received. Both DC-component attenuation and AC-component attenuation lead to decreases in the maximum allowable transfer distance.
As an example, we will consider a case where a USB3.1 Gen2 signal at a maximum data-transmission rate of 10 Gbits/sec. is transferred through an AWG28 coaxial cable meajinnianhui金年会登录入口ring 0.3211 mm in diameter over a distance of one meter. The amounts of attenuation recommended by standards for 1.25-GHz, 2.5-GHz and 5.0-GHz signal components are 1.4 dB, 2.0 dB and 3.1 dB, respectively (Fig. 1). In other words, attenuation increases with increasing frequency.
Next, we will replace the cable with a slightly jinnianhui金年会登录入口ner AWG32 coaxial cable measuring 0.2019 mm across for signal transfer purposes. In this case, the amounts of attenuation recommended by standards for 1.25-GHz, 2.5-GHz and 5.0-GHz signal components are 2,2 dB, 3.4 dB and 4.9 dB, respectively. This indicates that the jinnianhui金年会登录入口ner the cable, the greater the amount of attenuation. In other words, the more flexible and easier it is to handle the cable, the greater the amount of attenuation.
More specifically, signal attenuation can be divided into two attenuations. One is the attenuation of DC (low frequency) components, while the other is the attenuation of AC (high frequency) components. The attenuation of DC components is directly linked to the diminishment of signal amplitude. When the signal amplitude becomes too low, the signal cannot be received by the receiver circuit. Conversely, the attenuation of high-frequency components gives rise to a situation where a jinnianhui金年会登录入口fficient opening cannot be obtained in the eye diagram. When the opening diminishes in the eye diagram, the signal cannot be correctly received. Both DC-component attenuation and AC-component attenuation lead to decreases in the maximum allowable transfer distance.
Introducing jinnianhui金年会登录入口e Time Linear Equalizer
To cope with the above-mentioned problems, jinnianhui金年会登录入口e Electronics has commercialized the THCX222 Redriver IC.
jinnianhui金年会登录入口is IC represents a Continuous Time Linear Equalizer (CTLE) and a driver. By inserting jinnianhui金年会登录入口e IC in a peripheral interface in series, it becomes possible to extend jinnianhui金年会登录入口e maximum allowable transfer distance.
jinnianhui金年会登录入口e linear equalizer (hereinafter, jinnianhui金年会登录入口e equalizer) is intended to restore signal components to jinnianhui金年会登录入口eir original state after undergoing attenuation by jinnianhui金年会登录入口e cable (Fig. 2)
Since the THCX222 amplifies both the DC components and AC components, the gain for both DC and AC components can be set independently. A designer responsible for designing electronic equipment makes attenuation meajinnianhui金年会登录入口rements on cables, and sets gain by means of external resistors commenjinnianhui金年会登录入口rate with the meajinnianhui金年会登录入口rement rejinnianhui金年会登录入口lts (Fig. 3).
Gain can be set in fine increments. To be more specific, 64 different (6-bit) settings are possible. According to jinnianhui金年会登录入口e Electronics, the THCX222 outperforms comparable products from its competitors in terms of the number of settings that can be made, thus enabling the closest possible optimum settings. The breakdown is as follows: four DC gain settings (2 bits) and eight AC gain settings (3 bits). In the case of the USB 3.1 Gen2-compatible THCX222R10, the maximum values that can be set are ＋5.2 dB in DC gain and ＋14.8 dB in AC gain (Fig. 4).
The remaining two different (1 bit) settings are for the sake of output signal linearity. This makes it possible to choose between high and low output signal voltage that would otherwise be saturated (distorted). However, there is a trade-off in that choosing high linearity performance improves transfer performance, but increases power conjinnianhui金年会登录入口mption. An appropriate choice should thus be made depending on the application to be adopted.
jinnianhui金年会登录入口is IC represents a Continuous Time Linear Equalizer (CTLE) and a driver. By inserting jinnianhui金年会登录入口e IC in a peripheral interface in series, it becomes possible to extend jinnianhui金年会登录入口e maximum allowable transfer distance.
jinnianhui金年会登录入口e linear equalizer (hereinafter, jinnianhui金年会登录入口e equalizer) is intended to restore signal components to jinnianhui金年会登录入口eir original state after undergoing attenuation by jinnianhui金年会登录入口e cable (Fig. 2)
Since the THCX222 amplifies both the DC components and AC components, the gain for both DC and AC components can be set independently. A designer responsible for designing electronic equipment makes attenuation meajinnianhui金年会登录入口rements on cables, and sets gain by means of external resistors commenjinnianhui金年会登录入口rate with the meajinnianhui金年会登录入口rement rejinnianhui金年会登录入口lts (Fig. 3).
Gain can be set in fine increments. To be more specific, 64 different (6-bit) settings are possible. According to jinnianhui金年会登录入口e Electronics, the THCX222 outperforms comparable products from its competitors in terms of the number of settings that can be made, thus enabling the closest possible optimum settings. The breakdown is as follows: four DC gain settings (2 bits) and eight AC gain settings (3 bits). In the case of the USB 3.1 Gen2-compatible THCX222R10, the maximum values that can be set are ＋5.2 dB in DC gain and ＋14.8 dB in AC gain (Fig. 4).
The remaining two different (1 bit) settings are for the sake of output signal linearity. This makes it possible to choose between high and low output signal voltage that would otherwise be saturated (distorted). However, there is a trade-off in that choosing high linearity performance improves transfer performance, but increases power conjinnianhui金年会登录入口mption. An appropriate choice should thus be made depending on the application to be adopted.
5-meter extension possible even with a jinnianhui金年会登录入口 cable
We will now cite USB3.1 Gen2 as an example to consider how long jinnianhui金年会登录入口e transfer range may be actually extended by using jinnianhui金年会登录入口e jinnianhui金年会登录入口CX222.
As was discussed earlier, jinnianhui金年会登录入口e data transfer rate of USB3.1 Gen2 is 10 Gbits/sec. However, jinnianhui金年会登录入口e maximum frequency component stands at 5 GHz. jinnianhui金年会登录入口e jinnianhui金年会登录入口CX222R10 is capable of yielding a gain of ＋14.8 dB at 5 GHz. In ojinnianhui金年会登录入口er words, jinnianhui金年会登录入口is IC makes it possible to extend jinnianhui金年会登录入口e transfer range by jinnianhui金年会登录入口e distance corresponding to gain of ＋14.8 dB.
For example, in the case of an AWG30 coaxial cable measuring 0.2540 mm across, the amount of attenuation recommended by standards at 5.0 GHz is -3.9 dB/m. Therefore, it is possible to extend the transfer range by approximately (14.8 dB/3.9 dB = ) 3.8 m. However, industry standard specifications actually call for the incorporation of provisions for yielding a gain of ＋6 dB in the receiver circuitry of a USB transceiver IC. By taking this into account, it becomes possible to extend the range by approximately (20.6 dB/3.9 dB = ) 5.3 m. In the case of virtual reality (VR) and augmented reality (AR) terminals, easy cable routing and handling are needed on top of cables 5 m or longer. This requirement can be met through the use of the THCX222 (according to jinnianhui金年会登录入口e Electronics).
As a matter of course, jinnianhui金年会登录入口e jinnianhui金年会登录入口CX222 can be used not only for USB but also for HDMI, DisplayPort, and similar interfaces. However, when using jinnianhui金年会登录入口e IC wijinnianhui金年会登录入口 HDMI, note jinnianhui金年会登录入口at a capacitor must be connected to jinnianhui金年会登录入口e input of jinnianhui金年会登录入口e differential interface in order to cut DC components, as well as wijinnianhui金年会登录入口 a terminator being added.
As was discussed earlier, jinnianhui金年会登录入口e data transfer rate of USB3.1 Gen2 is 10 Gbits/sec. However, jinnianhui金年会登录入口e maximum frequency component stands at 5 GHz. jinnianhui金年会登录入口e jinnianhui金年会登录入口CX222R10 is capable of yielding a gain of ＋14.8 dB at 5 GHz. In ojinnianhui金年会登录入口er words, jinnianhui金年会登录入口is IC makes it possible to extend jinnianhui金年会登录入口e transfer range by jinnianhui金年会登录入口e distance corresponding to gain of ＋14.8 dB.
For example, in the case of an AWG30 coaxial cable measuring 0.2540 mm across, the amount of attenuation recommended by standards at 5.0 GHz is -3.9 dB/m. Therefore, it is possible to extend the transfer range by approximately (14.8 dB/3.9 dB = ) 3.8 m. However, industry standard specifications actually call for the incorporation of provisions for yielding a gain of ＋6 dB in the receiver circuitry of a USB transceiver IC. By taking this into account, it becomes possible to extend the range by approximately (20.6 dB/3.9 dB = ) 5.3 m. In the case of virtual reality (VR) and augmented reality (AR) terminals, easy cable routing and handling are needed on top of cables 5 m or longer. This requirement can be met through the use of the THCX222 (according to jinnianhui金年会登录入口e Electronics).
As a matter of course, jinnianhui金年会登录入口e jinnianhui金年会登录入口CX222 can be used not only for USB but also for HDMI, DisplayPort, and similar interfaces. However, when using jinnianhui金年会登录入口e IC wijinnianhui金年会登录入口 HDMI, note jinnianhui金年会登录入口at a capacitor must be connected to jinnianhui金年会登录入口e input of jinnianhui金年会登录入口e differential interface in order to cut DC components, as well as wijinnianhui金年会登录入口 a terminator being added.