Redriver and resistive unit for redriver

Abstract

Embodiments of a re-driver and a resistance unit for a re-driver are disclosed. In an embodiment, a resistance unit for a re-driver comprises at least one resistor connected to an input / output of the re-driver, at least one switch connected in series to the at least one resistor, and a voltage regulator connected to the at least one switch and configured to generate a termination voltage for the at least one switch. Using the voltage regulator can avoid large voltage jumps at the input / output to keep the connected device safe, instead of grounding the at least one resistor.

Description

TECHNICAL FIELD

[0001] The present invention relates to a re-driver. BACKGROUND

[0002] Re-drivers can be used to provide signal amplification and / or waveform shaping such that the transmitted signal exhibits the intended effect over a long channel. For example, re-drivers can be used to reduce insertion loss. Typically, re-drivers support multiple modes of operation. However, switching between different modes of operation can cause a sudden change in voltage at one or more input and / or output terminals of the re-driver. Typically, the input / output terminals of the re-driver are electrically connected to a decoupling capacitor having a large capacitance value, which can isolate the direct current (DC) level of the re-driver input / output from an integrated circuit (IC) chip electrically connected to the re-driver, which is located before or after the re-driver in the signal path. Due to the large capacitance value of the decoupling capacitor, a sudden change in voltage at the input / output terminals of the re-driver can damage the connected IC chip if the absolute maximum voltage of the IC chip is lower than the voltage at the input / output terminals due to the sudden change in voltage. Therefore, there is a need for a re-driver that is capable of switching between different modes of operation without causing a sudden change in voltage at the input / output terminals of the re-driver. SUMMARY

[0003] Embodiments of a re-driver and a resistance unit for a re-driver are disclosed. In an embodiment, a resistance unit for a re-driver includes at least one resistor connected to an input / output terminal of the re-driver, at least one switch connected in series to the at least one resistor, and a voltage regulator connected to the at least one switch and configured to generate a termination voltage for the at least one switch. Other embodiments are also described.

[0004] In an embodiment, the voltage regulator is further configured to generate the termination voltage for the at least one switch in response to a supply voltage of the re-driver.

[0005] In an embodiment, the termination voltage is lower than the supply voltage of the re-driver and higher than a reference voltage.

[0006] In an embodiment, the reference voltage is zero volts.

[0007] In an embodiment, the voltage regulator includes a diode arrangement connected to a DC voltage, a second resistor connected between the diode arrangement and the reference voltage, and a voltage output connected to the diode arrangement and the second resistor and configured to output the termination voltage to the at least one switch.

[0008] In an embodiment, the DC voltage is equal to the supply voltage of the re-driver.

[0009] In an embodiment, the termination voltage is lower than a power supply voltage of the re-driver and higher than a reference voltage.

[0010] In an embodiment, the reference voltage is zero volts.

[0011] In an embodiment, the resistance unit further includes a capacitor connected to the diode device, the second resistor, and the voltage output.

[0012] In an embodiment, the diode device includes a transistor.

[0013] In an embodiment, a resistance unit for a re-driver includes: a first resistor and a second resistor connected to an input / output of the re-driver; a first switch and a second switch connected in series to the first resistor and the second resistor, respectively; and a voltage regulator connected to the first switch and the second switch and configured to generate a DC termination voltage for the first switch and the second switch in response to a DC power supply voltage of the re-driver, wherein the termination voltage is lower than the DC power supply voltage of the re-driver and higher than a DC reference voltage.

[0014] In an embodiment, the voltage regulator includes: a diode device connected to the DC power supply voltage of the re-driver; a third resistor connected between the diode device and the DC reference voltage; and a voltage output connected to the diode device and the third resistor and configured to output the DC termination voltage to the first switch and the second switch.

[0015] In an embodiment, the DC reference voltage is zero volts.

[0016] In an embodiment, the resistance unit further includes a capacitor connected to the diode device, the third resistor, and the voltage output.

[0017] In an embodiment, the diode device includes a transistor.

[0018] In an embodiment, a re-driver includes a continuous time linear equalizer (CTLE) configured to perform signal equalization, a transmitter driver configured to generate a driver signal in response to the signal equalization, a first resistance unit connected to the CTLE or the transmitter driver and an input / output terminal of the re-driver, and a second resistance unit connected to the CTLE or the transmitter driver and the input / output terminal of the re-driver. The first resistance unit includes a first resistor and a second resistor connected to the input / output terminal of the re-driver, a first switch and a second switch connected in series to the first resistor and the second resistor, respectively, and a voltage regulator connected to the first switch and the second switch and configured to generate a DC termination voltage for the first switch and the second switch in response to a DC supply voltage of the re-driver, wherein the termination voltage is lower than the DC supply voltage of the re-driver and higher than a DC reference voltage. The second resistance unit includes a third and a fourth resistor connected to the input / output terminal of the re-driver, and a third and a fourth switch connected in series to the third and the fourth resistor and to the DC supply voltage of the re-driver.

[0019] In an embodiment, the voltage regulator includes a diode device connected to the DC supply voltage of the re-driver, a fifth resistor connected between the diode device and the DC reference voltage, and a voltage output terminal connected to the diode device and the fifth resistor and configured to output the DC termination voltage to the first switch and the second switch.

[0020] In an embodiment, the re-driver further includes a capacitor connected to the diode device, the fifth resistor, and the voltage output terminal.

[0021] In an embodiment, the diode device includes a transistor.

[0022] In an embodiment, the DC reference voltage is zero volt.

[0023] Other aspects of the application will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the application. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic block diagram of a re-driver according to an embodiment of the application.

[0025] Figure 2 and Figure 3 depicted in single-ended form Figure 1 two embodiments of a transmitter driver of the depicted re-driver.

[0026] Figure 4 depicted is an embodiment of a voltage regulator of the depicted re-driver. Figure 1 depicted is an embodiment of a voltage regulator of the depicted re-driver.

[0027] Figure 5 Embodiments of a voltage regulator are depicted. Figure 4 Embodiments of a voltage regulator are depicted.

[0028] Figure 6 A re-driver system according to embodiments of the application is depicted, in which Figure 5 The depicted voltage regulator is shared by multiple safety mode resistors.

[0029] Throughout the specification, like drawing numbers can be used to identify like elements throughout the several views. DETAILED DESCRIPTION

[0030] It will be readily understood that the components of the embodiments, as generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the various embodiments, as represented in the figures, is not intended to limit the scope of the present disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0031] The application can be implemented in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the application is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

[0032] Reference throughout this specification to features, advantages, or similar language does not mean that all of the features and advantages that can be realized with the present application should be or are in any single embodiment of the application. Rather, language referring to the features and advantages is understood to mean that a particular feature, advantage, or characteristic is included in at least one embodiment of the application. As such, features and advantages throughout the specification that are not necessarily

[0033] Furthermore, the described features, advantages, and characteristics of the application can be combined in any suitable manner in one or more embodiments. Those skilled in the relevant art will recognize that the application can be practiced with

[0034] References throughout this specification to "one embodiment", "an embodiment", or similar language mean that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment of the present application. Thus, the phrase "in one embodiment", "in an embodiment", and similar language throughout this specification can, but not always, refer to the same embodiment.

[0035] Figure 1 is a schematic block diagram of a re-driver 100 according to an embodiment of the present application. The re-driver can be used to provide signal amplification and / or waveform shaping such that the transmitted signal exhibits the intended effects over long channels. For example, the re-driver can be used to reduce insertion loss and / or address other signal integrity challenges. In Figure 1 In the depicted embodiment, the re-driver generates a desired output signal 114 in response to an input signal 112. The re-driver can be used in various applications, such as automotive applications, communications applications, industrial applications, medical applications, computer applications, and / or consumer or appliance applications. For example, the re-driver can be used in Universal Serial Bus (USB), Thunderbolt interface (TBT), DisplayPort (DP), and / or CIO applications. In Figure 1 In the depicted embodiment, the re-driver includes a continuous time linear equalizer (CTLE) 102, a transmitter driver 104, a receiver resistance termination unit 106, a receiver safe mode resistance unit 108, a receiver common mode keeper (CMK) circuit 110, a transmitter resistance termination unit 116, a transmitter safe mode resistance unit 118, and a transmitter CMK circuit 120. In some embodiments, the re-driver is a linear re-driver that matches the incoming waveform to the outgoing waveform. In other embodiments, the re-driver is a limiting (non-linear) re-driver that does not precisely match the outgoing waveform to the incoming waveform. In Figure 1In the depicted embodiment, the re-driver is electrically connected to decoupling capacitors 126-1, 126-2, 126-3, 126-4 and resistors 128-1, 128-2, 128-3, 128-4, which are connected to a reference voltage, e.g., ground. In some embodiments, at least one of the decoupling capacitors 126-1, 126-2, 126-3, 126-4 has a capacitance value in the range of 100 nF, and at least one of the resistors 128-1, 128-2, 128-3, 128-4 has a resistance value in the range of 200 K Ohms. In some embodiments, the re-driver is implemented in a substrate, and packaged as a standalone semiconductor IC device or chip. In these embodiments, the decoupling capacitors and resistors are external to the re-driver. In some embodiments, the re-driver is included in a computing device, e.g., a smartphone, tablet computer, laptop computer, etc. In some embodiments, at least some components of the re-driver are implemented in a substrate, e.g., a semiconductor wafer or printed circuit board (PCB). In embodiments, at least some components of the re-driver are packaged as a standalone semiconductor IC chip. Although the re-driver is shown in Figure 1 In the depicted embodiment, the re-driver is electrically connected to decoupling capacitors 126-1, 126-2, 126-3, 126-4 and resistors 128-1, 128-2, 128-3, 128-4, which are connected to a reference voltage, e.g., ground. In some embodiments, at least one of the decoupling capacitors 126-1, 126-2, 126-3, 126-4 has a capacitance value in the range of 100 nF, and at least one of the resistors 128-1, 128-2, 128-3, 128-4 has a resistance value in the range of 200 K Ohms. In some embodiments, the re-driver is implemented in a substrate, and packaged as a standalone semiconductor IC device or chip. In these embodiments, the decoupling capacitors and resistors are external to the re-driver. In some embodiments, the re-driver is included in a computing device, e.g., a smartphone, tablet computer, laptop computer, etc. In some embodiments, at least some components of the re-driver are implemented in a substrate, e.g., a semiconductor wafer or printed circuit board (PCB). In embodiments, at least some components of the re-driver are packaged as a standalone semiconductor IC chip. Although the re-driver is shown in

[0036] In Figure 1 In the depicted embodiment, the re-driver 100 supports multiple operating modes. Examples of operating modes supported by the re-driver include, but are not limited to, a power saving operating mode, a safe state operating mode, a USB operating mode, a DP operating mode, a TBT operating mode, a CIO operating mode, and a far end termination detection operating mode. Switching between different operating modes in the re-driver can cause a sudden change in voltage at one or more of the inputs 132-1, 132-2 and / or outputs 134-1, 134-2 of the re-driver. Because the capacitance values of the decoupling capacitors 126-1, 126-2, 126-3, 126-4 are typically large (e.g., in the range of 100 nF or more), a sudden change in voltage at the inputs / outputs of the re-driver can damage electronic devices, e.g., IC chips, that are located before or after the re-driver in the signal path if the absolute maximum voltage of the electronic devices is lower than the voltage at the inputs / outputs due to the sudden change in voltage. In Figure 1 In the depicted embodiment, because the termination voltages of the transmitter safe mode resistance unit and the receiver resistance termination unit are lower than the direct current (DC) supply voltage V DDTherefore, the re-driver can switch between different operating modes without causing sudden changes in the voltage at the input / output terminals of the re-driver, as explained further below.

[0037] exist Figure 1 In the depicted embodiment, CTLE 102 is configured to perform signal equalization on input signal 112. Known architectures can be used to implement the CTLE. In some embodiments, the CTLE is used in conjunction with an input buffer preceding it and multiple amplifiers with different gains. For example, the CTLE may include an amplifier with low-frequency gain and an amplifier with peak gain to form the desired AC response or equalization.

[0038] exist Figure 1 In the depicted embodiment, the transmitter driver 104 is configured to generate a driver signal in response to signal equalization performed by CTLE 102. The transmitter driver may be implemented using one or more PNP transistors, one or more PMOS transistors, one or more NPN transistors, and / or one or more NMOS transistors. In embodiments using NPN or NMOS transistors to implement the transmitter driver, a 50-ohm terminating resistor may be connected to the DC power supply voltage V of the re-driver 100. DD Instead of terminating to a reference voltage such as ground.

[0039] Figure 2 An NMOS transistor-based emitter driver 204 is depicted, and Figure 3 An emitter driver 304 based on an NPN transistor is depicted. Figure 2 and Figure 3 The transmitter driver described is of single-ended form. Figure 1 An embodiment of the transmitter driver 104 is depicted. However, Figure 1 The transmitter driver 104 described is not limited to Figure 2 and Figure 3 The illustrated embodiment. Figure 2 In the depicted embodiment, the transmitter driver 204 includes a current source 260 connected to a reference voltage, such as ground, and a DC power supply voltage V connected to the re-driver 100 via, for example, a 50-ohm terminating resistor 264. DD The NMOS transistor 262. Input voltage V. i The input is given to the gate terminal G of the NMOS transistor, and the output voltage V is... o It is input to the drain terminal D of the NMOS transistor. Figure 3 In the depicted embodiment, the transmitter driver includes a current source 360 ​​connected to a reference voltage, such as ground, and a DC power supply voltage V connected to the re-driver via, for example, a 50-ohm terminating resistor 364.DD The NPN transistor 362. Input voltage V. i The input is given to the base terminal B of the NPN transistor, and the output voltage V o It is input to the collector terminal C of the NPN transistor.

[0040] During switching between different operating modes, such as switching between a security operating mode and a USB operating mode, the termination resistor switch is enabled. In this embodiment, because the load resistance can be approximately 200k ohms and the termination resistor value is typically 50 ohms, the voltage at the outputs 134-1 and 134-2 of the re-driver 100 is almost at the DC supply voltage V of the re-driver 100. DD The voltage level. Because decoupling capacitors typically have large capacitance values ​​(e.g., in the range of 100nF or greater), voltage jumps can be directly transmitted to the load device, which can potentially damage the load device.

[0041] exist Figure 1 In the depicted re-driver 100, each of the receiver safety mode resistor unit 108 and the transmitter safety mode resistor unit 118 is connected to a DC termination voltage V. T This voltage is close to the DC power supply voltage V of the re-driver 100. DD Instead of grounding. For example, the DC termination voltage could be approximately 1.2 volts (e.g., within ±30% of 1.2 volts), and the DC supply voltage V of the driver. DD This can be approximately 1.8 volts (e.g., within ±10% of 1.8 volts). When the receiver safety mode resistor unit and the transmitter safety mode resistor unit are terminated to ground, a voltage change of approximately 1.8 volts is presented at the input / output terminals 132-1, 132-2, 134-1, or 134-2 of the re-driver during switching between different operating modes in the re-driver (i.e., from zero volts to approximately 1.8 volts, the DC supply voltage V of the re-driver). DD However, when the receiver safety mode resistor unit and the transmitter safety mode resistor unit are terminated with a DC termination voltage, a voltage change of 0.6 volts occurs at the input / output terminals of the re-driver during the switching between different operating modes in the re-driver (i.e., from 1.2 volts to 1.8 volts, the DC power supply voltage V of the re-driver). DD). Thus, the magnitude of voltage variation at the input / output terminals of the re-driver due to switching between different operating modes in the re-driver is reduced. In some embodiments, to reduce the voltage swing at the input / output terminals of the re-driver during switching between different operating modes, the receiver CMK circuit 110 and the transmitter CMK circuit 120 remain on. However, the current consumption of the receiver CMK circuit and the transmitter CMK circuit can be high. For example, for a 4-channel re-driver, about 80-200 microamperes (pA) of current can be consumed, which is higher than the current threshold for the power saving mode. In comparison to the re-driver embodiments in which the receiver CMK circuit and the transmitter CMK circuit remain on, terminating the receiver safety mode resistance unit and the transmitter safety mode resistance unit to the DC termination voltage V T , which is close to the DC supply voltage V DD of the re-driver, does not cause the same spike in current consumption. For example, terminating the receiver safety mode resistance unit and the transmitter safety mode resistance unit to the DC termination voltage V T may cause an increase in current of 1 pA in any operating mode of the re-driver. Thus, Figure 1 The re-driver in the depicted embodiment can be used in the power saving mode.

[0042] In Figure 1 the depicted embodiment, the receiver safety mode resistance unit 108 is electrically connected to the CTLE 102 and the input terminals 132-1, 132-2 of the re-driver 100. In some embodiments, the receiver safety mode resistance unit is used to show the minimum impedance at which the re-driver is turned off. The receiver safety mode resistance unit includes two resistors 140, 142 electrically connected to the input terminals 132-1, 132-2 of the re-driver, two switches 144, 146 connected in series to the resistors 140, 142, and a voltage regulator 148 electrically connected to the switches 144, 146 and configured to generate a DC termination voltage V DD for the switches 144, 146 in response to the DC supply voltage V T of the re-driver. In some embodiments, to be compatible with the USB standard, the receiver safety mode resistance unit is not terminated to the DC supply voltage V DD of the re-driver. In some embodiments, the termination voltage is lower than the DC supply voltage V DD of the re-driver and higher than a DC reference voltage, such as ground. The resistance values of the resistors 140, 142 can be about 45 KOhms (e.g., within ±30% of 45 KOhms). In some embodiments, the receiver safety mode resistance unit includes one or more processors, such as a digital state machine, a microcontroller, or a central processing unit (CPU), configured to control the switches.

[0043] In Figure 1 In the depicted embodiment, the receiver CMK circuit 110 includes two resistors 150, 152, two switches 154, 156, and two current sources 158, 160. The resistors 150, 152 can have a resistance of about 20 KOhms (e.g., within ±30% of 20 KOhms). In some embodiments, the receiver CMK circuit includes one or more processors, such as a digital state machine, microcontroller, or CPU, configured to control the switches.

[0044] In Figure 1 In the depicted embodiment, the receiver resistance termination unit 106 is electrically connected to the CTLE 102 and the input terminals 132-1, 132-2 of the re-driver 100. The receiver resistance termination unit includes two resistors 162, 164 electrically connected to the input terminals 132-1, 132-2 of the re-driver, and two switches 166, 168 respectively connected in series to the resistors and in series to the DC supply voltage V DD of the re-driver. The resistors 162, 164 can have a resistance of about 50 Ohms (e.g., within ±30% of 50 Ohms). In some embodiments, the receiver resistance termination unit includes one or more processors, such as a digital state machine, microcontroller, or CPU, configured to control the switches.

[0045] In Figure 1 In the depicted embodiment, the transmitter safety mode resistance unit 118 is electrically connected to the transmitter driver 104 and the output terminals 134-1, 134-2 of the re-driver 100. In some embodiments, the transmitter safety mode resistance unit is used to show a minimum impedance when the re-driver is off. The transmitter safety mode resistance unit includes two resistors 170, 172 electrically connected to the output terminals 134-1, 134-2 of the re-driver, two switches 174, 176 connected in series to the resistors 170, 172, and a voltage regulator 178 electrically connected to the switches 174, 176 and configured to generate a DC termination voltage V DD for the switches 174, 176 in response to the DC supply voltage V T of the re-driver. In some embodiments, to be compatible with the USB standard, the receiver safety mode resistance unit is not terminated to the DC supply voltage V DD of the re-driver. In some embodiments, the termination voltage V T is lower than the DC supply voltage V DDAnd higher than, for example, a DC reference voltage grounded. The resistance values ​​of resistors 170 and 172 can be approximately 45 kΩ (e.g., within ±30% of 45 kΩ). In some embodiments, the transmitter safety mode resistor unit includes one or more processors, such as a digital state machine, microcontroller, or CPU, configured to control the switch.

[0046] exist Figure 1 In the depicted embodiment, the transmitter CMK circuit 120 includes two resistors 180 and 182, two switches 184 and 186, and two current sources 188 and 190. The resistance values ​​of resistors 180 and 182 may be approximately 25 kΩ (e.g., within ±30%). In some embodiments, the transmitter CMK circuit includes one or more processors, such as a digital state machine, microcontroller, or CPU, configured to control the switches.

[0047] exist Figure 1 In the depicted embodiment, the transmitter resistor termination unit 116 is electrically connected to the transmitter driver 104 and output terminals 134-1 and 134-2 of the re-driver 100. The transmitter resistor termination unit includes: two resistors 192 and 194 electrically connected to the output terminals 134-1 and 134-2 of the re-driver; and two switches 196 and 198, respectively connected in series with the resistors 192 and 194 and in series with the DC power supply voltage V of the re-driver. DD The resistance values ​​of resistors 192 and 194 can be approximately 50 ohms (e.g., within ±30% of 50 ohms). In some embodiments, the transmitter resistor termination unit includes one or more processors, such as a digital state machine, microcontroller, or CPU, configured to control the switch.

[0048] Figure 4 The voltage regulator 448 is described. Figure 1 The embodiments depicted include the voltage regulator 148 of the receiver safety mode resistor unit 108 or the voltage regulator 178 of the transmitter safety mode resistor unit 118. However, Figure 1 The voltage regulators 148 and 178 described are not limited to Figure 4 The illustrated embodiment. Figure 4 In the depicted embodiment, the voltage regulator includes a diode device 480 electrically connected to the DC power supply voltage V of the re-driver. DD Resistor 482, electrically connected between the diode assembly and a DC reference voltage (e.g., ground); and voltage output terminal 484, electrically connected to the diode assembly and resistor 482, and configured to output a DC terminal voltage V. T DC terminal connected to voltage V TThe depicted voltage regulator can be implemented in a small substrate area. Moreover, compared to complex regulators, Figure 4 The depicted voltage regulator has a low current consumption. Figure 4

[0049] In some embodiments, the diode device 480 of the voltage regulator 448 is implemented using a transistor. Figure 5 A voltage regulator 548 is depicted, which is implemented using an NPN transistor 580. Figure 4 The depicted embodiment of the voltage regulator 448. However, Figure 4 The depicted voltage regulator 448 is not limited to Figure 5 The depicted embodiment. In Figure 5 In the depicted embodiment, the voltage regulator 548 includes: an NPN transistor 580 electrically connected to a DC supply voltage V DD ; a resistor 582 electrically connected between the NPN transistor 580 and a DC reference voltage (e.g., ground); a voltage output 584 electrically connected to the NPN transistor 580 and the resistor 528 and configured to output a DC termination voltage V T ; and a capacitor 586 electrically connected to the NPN transistor 580, the resistor 582, and the voltage output 584 configured to stabilize the DC termination voltage V T The DC termination voltage V T may be applied to the switches 144, 146 of the receiver safety mode resistance unit 108 or the switches 174, 176 of the transmitter safety mode resistance unit 118.

[0050] Figure 6 A re-driver system 640 according to an embodiment of the present application is depicted, wherein Figure 5 The depicted voltage regulator is shared by a plurality of safety mode resistors 650-1, 650-2, 650-3, 650-4, 650-5, 650-6. In Figure 6 In the depicted embodiment, the re-driver system includes: a voltage regulator 548 configured to generate a DC termination voltage V DD in response to a DC supply voltage V T ​; four transmitter drivers 604-1, 604-2, 604-3, 604-4; four safety mode resistors 650-1, 650-2, 650-3, 650-4, 650-5, 650-6; six termination resistors 660-1, 660-2, 660-3, 660-4, 660-5, 660-6; and twelve switches 670-1, 670-2, 670-3, 670-4, 670-5, 670-6, 670-7, 670-8, 670-9, 670-10, 670-11, 670-12. In some embodiments, the DC termination voltage V T is about 1.2 volts (e.g., within ±30% thereof), and the DC supply voltage V DD of the re-driver system is about 1.8 volts (e.g., within ±10% thereof). The safety mode resistors 650-1, 650-2, 650-3, 650-4, 650-5, 650-6 are Figure 1 depicted embodiments of safety mode resistors 140, 142, 170, or 172. The four transmitter drivers 604-1, 604-2, 604-3 are Figure 1 depicted embodiments of transmitter drivers 104. The termination resistors 660-1, 660-2, 660-3, 660-4, 660-5, 660-6 are Figure 1 depicted embodiments of termination resistors 162, 164, 192, or 194. The switches 670-1, 670-2, 670-3, 670-4, 670-5, 670-6, 670-7, 670-8, 670-9, 670-10, 670-11, 670-12 are Figure 1 depicted embodiments of switches 144, 146, 166, 168, 174, 176, 196, or 198. In Figure 6 the depicted embodiments, the voltage regulator 548 is shared by the six safety mode resistors 650-1, 650-2, 650-3, 650-4, 650-5, 650-6, and the DC termination voltage V T generated by the voltage regulator is supplied to the six safety mode resistors 650-1, 650-2, 650-3, 650-4, 650-5, 650-6. In some embodiments, the termination resistors 660-1, 660-2, 660-3, 660-4, 660-5, 660-6 have a resistance value of 50 ohms.

[0051] In the above description, specific details of various embodiments are provided. However, some embodiments can be practiced with less than all of the specific details. In other instances, some methods, processes, components, structures, and / or functions are not described in detail in order to avoid obscuring the various embodiments of the application.

[0052] Although the operations of the methods herein are shown and described in a particular order, the order of the operations can be altered so that certain operations can be performed in an inverse order or so that certain operations can be performed, at least in part, concurrently with other operations. In another embodiment, instructions or sub-operations of distinct operations can be implemented in an intermittent and / or alternating manner.

[0053] It should also be noted that at least some of the operations of the methods described herein can be implemented using software stored on computer-usable storage medium for execution by a computer. As an example, an embodiment of a computer program product includes a computer-usable storage medium to store a computer readable program. The computer-usable or computer-readable storage medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device). Examples of a non-transitory computer-usable and computer-readable storage medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disc, and an optical disk. Current examples of optical disks include compact disk - read only memory (CD-ROM), compact disk - read / write (CD-R / W) and DVD.

[0054] Alternatively, embodiments of the present application can be implemented in whole or in part in hardware, or in embodiments combining hardware and software elements. In embodiments employing software, the software can comprise, but is not limited to, firmware, resident software, microcode, etc.

[0055] Although specific embodiments of the present application have been described and illustrated, the present application is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the present application is to be defined by the claims appended hereto and their equivalents.

Claims

1. A resistance unit for a re-driver, characterized by, The resistance unit comprises: at least one resistor (140, 142) connected to one of the input and output terminals of the re-driver; at least one switch (144, 146) connected in series to the at least one resistor and configured to selectively connect a termination voltage to the at least one resistor; and a voltage regulator powered by a supply voltage of the re-driver, connected to the at least one switch and configured to generate the termination voltage at the at least one switch lower than the supply voltage and higher than zero volts; The resistance unit comprises: a termination resistor (162, 192, 660-5) connected to one of the input and output terminals; and another switch (166, 196, 670-11) connected in series between the resistor and the supply voltage.

2. The resistance unit according to claim 1, characterized in that The voltage regulator is further configured to generate the termination voltage for the at least one switch in response to a supply voltage of the re-driver.

3. The resistance unit according to claim 2, characterized in that The termination voltage is lower than the supply voltage of the re-driver and higher than a reference voltage.

4. The resistance unit according to claim 3, characterized in that The reference voltage is zero volts.

5. The resistance unit according to claim 1, characterized in that, The voltage regulator comprises: a diode arrangement connected to a direct current (DC) voltage; a second resistor connected between the diode arrangement and a reference voltage; and a voltage output connected to the diode arrangement and the second resistor and configured to output the termination voltage to the at least one switch.

6. The resistance unit according to claim 5, characterized in that The DC voltage is equal to a supply voltage of the re-driver.

7. The resistance unit according to claim 6, characterized in that The termination voltage is lower than the supply voltage of the re-driver and higher than the reference voltage.

8. A resistance unit for a re-driver, characterized by The resistance unit comprises: a first resistor and a second resistor connected to input / output terminals of the re-driver; a first switch and a second switch connected in series to the first resistor and the second resistor, respectively; and a voltage regulator connected to the first switch and the second switch and configured to generate a direct current (DC) termination voltage for the first switch and the second switch in response to a DC supply voltage of the re-driver, wherein the termination voltage is lower than the DC supply voltage of the re-driver and higher than a DC reference voltage, the voltage regulator being configured to generate the termination voltage at the at least one switch lower than the supply voltage and higher than zero volts; The resistance unit comprises: a termination resistor (162, 192, 660-5) connected to one of the input and output terminals; and another switch (166, 196, 670-11) connected in series between the resistor and the supply voltage.

9. The resistance unit according to claim 8, characterized in that The voltage regulator comprises: a diode arrangement connected to the DC supply voltage of the re-driver; a third resistor connected between the diode arrangement and the DC reference voltage; and a voltage output connected to the diode arrangement and the third resistor and configured to output the DC termination voltage to the first switch and the second switch.

10. A re-driver, comprising: The re-driver comprises: a continuous time linear equalizer (CTLE) configured to perform signal equalization; a transmitter driver configured to generate a driver signal in response to the signal equalization; a first resistance unit connected to the CTLE or the transmitter driver of the re-driver and an input / output terminal, the first resistance unit comprising: a first resistor and a second resistor connected to the input / output terminal of the re-driver; a first switch and a second switch connected in series to the first resistor and the second resistor, respectively; and a voltage regulator connected to the first switch and the second switch and configured to generate a direct current (DC) termination voltage for the first switch and the second switch in response to a DC supply voltage of the re-driver, wherein the termination voltage is lower than the DC supply voltage of the re-driver and higher than a DC reference voltage, the voltage regulator being configured to generate a termination voltage lower than the supply voltage and higher than zero volts at at least one switch; and a second resistance unit connected to the CTLE or the transmitter driver of the re-driver and the input / output terminal, the second resistance unit comprising: a third resistor and a fourth resistor connected to the input / output terminal of the re-driver; and a third switch and a fourth switch connected in series to the third resistor and the fourth resistor, respectively, and connected in series to the DC supply voltage of the re-driver; the first and second resistance units comprising a termination resistor (162, 192, 660-5) connected to one of the input and output terminals and another switch (166, 196, 670-11) connected in series between the resistor and the supply voltage.

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