Patent Application
20200089643
This relates generally to data networks including data networks having differential data paths.
Data networks include a number of network nodes coupled together over a data path such as a multi-point bus. In some scenarios, data networks are implemented using differential data paths. Differential data paths include a differential pair of signal lines. The differential pair of signal lines conveys differential signals between the network nodes. The differential pair of signal lines is characterized by a differential-mode impedance and a common-mode impedance.
If care is not taken, differential-mode impedance discontinuities at the ends of the data path can reflect the differential signals directly. Common-mode impedance discontinuities at the ends of the data path can reflect common-mode signals that are converted into differential noise and introduce errors in data conveyed over the data path. Impedance discontinuities thus leave the data path susceptible to external interference.
A system may include a data network and other components. The data network may include network nodes and a data path such as a multi-point bus. The data path may have first and second ends. The network nodes may be coupled to the data path between the first and second ends. The data path may be a differential data path having first and second differential signal lines that convey differential signals between the network nodes.
A bimodal impedance terminator may be coupled to the first and second differential signal lines at one or both ends of the data path. The bimodal impedance terminator may include a first resistor coupled between the first differential signal line and a circuit node and a second resistor coupled between the second differential signal line and the circuit node. A capacitor may be coupled between the circuit node and a reference potential such as ground. A third resistor may be coupled between the circuit node and ground in series with the capacitor. The bimodal impedance terminator may terminate both the differential-mode impedance and the common-mode impedance of the data path. In practical differential lines with minor imbalances, terminating both the differential-mode impedance and the common-mode impedance of the data path serves to reduce or minimize signal reflections at the ends of the data path and reduces or minimizes susceptibility of the data path to external electromagnetic noise.
The bimodal impedance terminator may be integrated within a connector that is configured to be coupled to (e.g., plugged into or mounted to) the first and second differential signal lines. The connector may have ground contacts that couple a cable shield or dedicated ground wire for the data path to ground. If desired, the connector may also couple a network node to the data path.
A system may include a data network and other components. The data network may include a data path such as a multi-point bus and two or more network nodes coupled to the data path. The network nodes may include one or more electronic devices or other electronic components. The data path may be a differential data path that includes a differential pair of signal lines. Differential signals may be conveyed between the network nodes over the differential pair of signal lines.
The differential pair of signal lines may have opposing first and second ends. Each of the network nodes may be coupled to the differential pair of signal lines between the first and second ends in a stub-node configuration. Impedance matching terminators (sometimes referred to herein as impedance terminators) may be coupled to the first and second ends to terminate the impedance of the differential pair of signal lines and to thereby reduce or minimize signal reflections at the first and second ends.
The impedance terminators may include circuitry for matching both the differential-mode and the common-mode impedance of the differential data path. Because the impedance terminators are configured to match both the differential and common mode impedances of the data path, the impedance terminators may sometimes be referred to herein as bimodal impedance terminators, bimodal impedance matching circuitry, or bimodal impedance matching circuits.
An illustrative system that may include a network with a differential data path and bimodal impedance terminators is shown in
System 10 has communications paths such as one or more data paths 14. System 10 may include two or more network nodes such as nodes 16 coupled to data path 14. Data path 14 may, for example, include parallel signal lines that form a data bus for network 14 and system 10. The parallel signal lines may include a differential pair of signal lines for conveying differential signals between two or more nodes 16 (e.g., data path 14 may be a multi-point differential bus). The differential signals may be used to convey communications data, control signals, sensor data, or any other desired information between nodes 16. The signal lines of data path 14 may include conductive wires or other conductors formed within one or more cables (e.g., Ethernet cables, coaxial cables, etc.), conductive traces on flexible and/or rigid printed circuits, and/or combinations of these structures. The signal lines may be arranged in a twisted pair configuration if desired. Connectors may be used to mechanically couple data path 14 to nodes 16 and/or to other network components.
Nodes 16 may include portable electronic devices such as laptop computers, cellular telephones, media players, wristwatch devices, head-mounted equipment such as goggles or headphones, larger electronic devices such as desktop computers, servers, line cards on a network rack, computers embedded within computer monitors, televisions, set-top boxes, gaming devices, computers embedded within a kiosk, vehicle network(s), accessories such as computer mice, keyboards, remote controls, or other accessories, electronic components such as sensors (e.g., image sensors, three-dimensional depth sensors, gaze tracking sensors, lidar sensors, radar sensors, inertial/motion sensors such as accelerometers, gyroscopes, or compasses, speedometers, odometers, ambient light sensors, infrared sensors, solar cells, proximity sensors, optical sensors, temperature sensors, magnetic sensors, ultrasonic sensors, microphones, audio sensors, humidity sensors, etc.), wireless communications circuitry (e.g., radio-frequency transceivers, AM/FM radio receivers, satellite radio receivers, satellite television receivers, satellite navigation receivers such as Global Positioning System or Global Navigation Satellite System receivers, wireless local area network transceivers, cellular telephone transceivers, wireless personal area network transceivers such as Bluetooth® transceivers, millimeter wave transceivers, near-field communications transceivers, optical signal transceivers, antennas, etc.), vehicle control components (e.g., steering control components, engine control components, cruise (speed) control components, air flow control components, power window motors, windshield wiper motors, brake control components, seat adjustment components, etc.), output devices (e.g., display components such as liquid crystal displays or light emitting diode displays, lights such as status indicator lights, cabin lights, or headlights, speaker components, haptic feedback and alert components, etc.), wireless charging circuitry for wirelessly charging portable electronic devices or other components in system 10, storage and processing circuits (e.g., processing circuitry such as one or more microprocessors, signal processors, microcontrollers, baseband processors, audio chips, and power management units, memory such as non-volatile memory and volatile memory, etc.), buttons, touch input devices, and/or other components coupled to data path 14.
System 10 may include other components 18 that are not a part of network 12. Other components 18 may include cosmetic structures, engine structures, wheels, input-output devices (e.g., sensor circuitry, communications circuitry, output devices, and/or input devices separate from network 12), and/or support structures used in mechanically supporting some or all of the components of system 10 such housing structures (e.g., conductive and/or dielectric housing walls), chassis structures (e.g., a metal chassis or frame for system 10), dashboard structures, windows, furniture, etc. If desired, system 10 may include multiple separate or interconnected networks 12. The example of
Differential signal lines 26H and 26L may convey differential signals between nodes 16. The differential signals include a first signal conveyed over differential signal line 26H and a complementary second signal (e.g., a signal of equal and opposite magnitude to the first signal at any given time) conveyed over differential signal line 26L (e.g., the first and second signals form a differential pair of signals). Differential signal line 26H may sometimes be referred to herein as high signal line 26H whereas differential signal line 26L is sometimes referred to herein as low signal line 26L.
In this way, any desired number of nodes 16 may be coupled to differential signal lines 26H and 26L between ends 21 and 23 of data path 14. If care is not taken, impedance discontinuities at ends 21 and 23 of data path 14 can reflect the signals conveyed over differential signal lines 26H and 26L. The reflected signals may undesirably interfere with the operation of nodes 16 and can introduce errors into the conveyed signals.
In order to reduce or minimize these impedance discontinuities, data path 14 may include one or more impedance termination circuits (impedance terminators) 20 such as first termination circuit 20-1 and second termination circuit 20-2 of
In some scenarios, a single resistor such as a 120-ohm resistor is coupled between the differential signal lines to terminate each end of the data path. In other scenarios, a split termination scheme is used in which a shunting capacitor is coupled to one differential signal line through a first 60-ohm resistor and to the other differential signal line through a second 60-ohm resistor. In other implementations, resistors of other values can be used. These arrangements may terminate the differential-mode impedance of the differential signal lines, but are incapable of terminating the common-mode impedance of the differential signal lines. If care is not taken, remaining common-mode impedance discontinuities will continue to reflect differential signals at the ends of the data path. It may therefore be desirable to be able to provide data path 14 with termination circuits that terminate both the differential-mode impedance and the common-mode impedance of differential signal lines 26H and 26L.
Capacitor 46 of
First resistor 44 may have resistance Rg. Resistance Rg may be equal to the difference between the common-mode impedance Zcomm of differential signal lines 26H and 26L and one-quarter of differential-mode impedance Zdiff (e.g., resistance Rg may be set to Zcomm−0.25*Zdiff, where “*” is the multiplication operator). Resistance Rg may be approximately equal to this value if desired (e.g., within 10-20% of Zcomm−0.25*Zdiff, within 10% of Zcomm−0.25*Zdiff, etc.). As an example, resistance Rg may be between 115 ohms and 125 ohms (e.g., 120 ohms), between 110 ohms and 130 ohms, between 100 ohms and 140 ohms, less than 100 ohms, between 140 ohms and 200 ohms, between 200 ohms and 300 ohms, between 230 ohms and 270 ohms (e.g., 250 ohms), or greater than 270 ohms. The example of
Resistor 40, resistor 42, and capacitor 46 may serve to terminate the differential-mode impedance of differential signal lines 26H and 26L. Coupling first resistor 44 in series between circuit node 38 and ground 32 may serve to terminate the common-mode impedance of differential signal lines 26H and 26L (e.g., without compromising the differential-mode termination provided by resistors 40 and 42). Because termination circuit 20 is capable of terminating both the common-mode impedance and the differential-mode impedance of differential signal lines 26L and 26H, termination circuit 20 may sometimes be referred to herein as bimodal impedance terminator circuit 20, bimodal impedance terminator 20, bimodal terminator 20, or bimodal terminator circuit 20.
Consider, for example, transmission line equivalent circuit models of bimodal impedance terminator 20 when coupled to differential signal lines 26L and 26H of
In the differential-mode equivalent circuit, a resistance of 2*Rt is coupled in series between terminal 34 (the positive transmission line) and terminal 36 (the negative transmission line). Resistance Rg, capacitance Ct, and ground 32 of
The positive and negative transmission lines in the differential-mode and common-mode equivalent circuits exhibit a per-unit-length self-capacitance C, a per-unit-length mutual-capacitance Cm, a per-unit-length self-inductance L, and a per-unit-length mutual-inductance Lm. The positive and negative transmission lines in the differential-mode equivalent circuit exhibit a differential-mode impedance of Zdiff, given by equation 1. The positive and negative transmission lines in the common-mode equivalent circuit exhibit a common-mode impedance of Zcomm, given by equation 2.
Z
diff=2*SQRT([L−Lm]/[C+Cm]) (1)
Z
comm=0.5*SQRT([L+Lm]/[C−Cm]) (2)
In equations 1 and 2, SQRT( ) is the square-root operator and “I” is the division operator. The common-mode equivalent circuit can be used to derive the common-mode input impedance Zin,c of bimodal impedance terminator 20, which is given by equation 3.
Z
in,c=(Rt/2)+Rg+1/(j*ω*Ct) (3)
In equation 3, ω is the angular frequency of the signals on the positive and negative transmission line conductors and j is equal to SQRT(−1). The amount of signals that are reflected at bimodal impedance terminator 20 back towards differential signal lines 26H and 26L (e.g., back towards the positive and negative transmission line conductors of the equivalent circuit models) is characterized by reflection coefficient ΓC, as given by equation 4.
ΓC=(Zin,c−Zcomm)/(Zin,c+Zcomm) (4)
Reflection coefficient ΓC is a complex number having a magnitude |ΓC|=SQRT(W2+Y2), where W is the real part of reflection coefficient ΓC and Y is the imaginary part of reflection coefficient ΓC. Substituting equation (3) into equation (4), the magnitude |ΓC| of reflection coefficient ΓC is given by equation 5.
|ΓC|=SQRT([|ω2*Ct2*(Rt/2+Rg−Zcomm)2+1]/[(ω2*Ct2*(Rt/2+Rg+Zcomm)2+1]) (5)
Assuming that common-mode impedance Zcomm is greater than Rt/2, Rg can be set equal to Zcomm−Rt/2. This allows magnitude |ΓC| of reflection coefficient ΓC to be simplified, as shown by equation 6.
|ΓC|=SQRT(1/[ω2*Ct2*(2*Zcomm)2+1]) (6)
Curve 45 represents the magnitude of the common mode reflection coefficient in scenarios where a split termination scheme is used (e.g., scenarios in which a shunting capacitor is coupled to one differential signal line through a first Rt resistor and to the other differential signal line through a second Rt resistor without resistor 44 of
Curve 47 represents magnitude |ΓC| of common mode reflection coefficient ΓC in scenarios where bimodal impedance terminator 20 of
Bimodal impedance terminator 20 may be integrated within network 12 in any desired manner. In one suitable arrangement which is sometimes described herein as an example, bimodal impedance terminator 20 may be integrated within a connector (adapter) for network 12. The connector may be coupled to (e.g., plugged into) data path 14 so that differential signal lines 26H and 26L are coupled to terminals 34 and 36 of bimodal impedance terminator 20 (
For example, contact 52 may be coupled to differential signal line 26H and contact 58 may be coupled to differential signal line 26L of
As shown in
Terminal 34 of bimodal impedance terminator 20 may be coupled to both contacts 64 and 52 of connector 48. Terminal 36 may be coupled to both contacts 60 and 58 of connector 48. In this way, terminals 34 and 36 of bimodal impedance terminator 20 may be coupled to differential signal lines 26H and 26L when connector 48 is connected to data path 14. Capacitor 46 may be coupled to ground 32 via grounded shield 50. In the example of
Contacts 52, 54, and 58 may be formed from male connector structures (e.g., pins) that are configured to mate with female connector structures on data path 14, may be formed from female connector structures (e.g., pin receptacles) that are configured to mate with male connector structures on data path 14, or may be formed from other connector structures such as contact pads, conductive adhesive, conductive springs, solder balls, welds, conductive wire, sheet metal, and/or any other desired conductive structures. Similarly, contacts 64, 62, and 60 may be formed from male connector structures that are configured to mate with female connector structures on a given node 16 or elsewhere in network 12, may be formed from female connector structures that are configured to mate with male connector structures on the given node 16 or elsewhere in network 12, or may be formed from other connector structures such as contact pads, conductive adhesive, conductive springs, solder balls, welds, and/or any other desired conductive structures.
Connector 48 may include attachment structures (e.g., clips, adhesive, pins, alignment posts, sockets, fixtures, etc.) that secure connector 48 to a mating connector on data path 14 or elsewhere in network 12 (e.g., to ensure that connector 48 is secured in place and a reliable electrical connection is established between bimodal impedance terminator 20 and differential signal lines 26H and 26L). The attachment structures may also allow connector 48 to be detached from the mating connector if desired. Grounded shield 50 may be omitted if desired (e.g., circuit node 56 may be coupled to ground 32 over other grounding structures).
Integrating bimodal impedance terminator 20 into a connector for network 12 such as connector 48 of
If desired, differential signal lines 26H and 26L of data path 14 may be formed from a twisted pair of conductors (e.g., a first wire that forms differential signal line 26H may be twisted around a second wire that forms differential signal line 26L). Forming differential signal lines 26H and 26L from a twisted pair of conductors may serve to reduce or minimize electromagnetic radiation by differential signal lines 26H and 26L, interference from external sources onto differential signal lines 26H and 26L, and/or electromagnetic crosstalk between differential signal lines 26H and 26L, as examples.
If desired, differential signal lines 26H and 26L may be formed within a shielded cable to further isolate the differential signal lines from external electromagnetic energy. The shielded cable may include a shield structure that surrounds differential signal lines 26H and 26L. The shield structure may electromagnetically shield differential signal lines 26H and 26L from electromagnetic noise and interference. The shield structure may include, for example, a conductive braid or other outer conductor that is wrapped around differential signal lines 26H and 26L.
Connectors 48A and 48B in the example of
Nodes 16 that are coupled to differential signal lines 26H and 26L through a corresponding connector 48 may sometimes be referred to herein as end nodes 16E. In the example of
Data path 14 of
In another suitable arrangement, data path 14 may include a dedicated ground wire.
The example of
In scenarios where data path 14 does not include a dedicated ground wire or cable shield, resistance RG in bimodal impedance terminators 20-1 and 20-2 (e.g., as shown in
Conductive shell 78 may surround (define) an interior cavity 91. If desired, conductive shell 78 may include one or more conductive ledges such as catch bars 90 within interior cavity 91. A ground plate such as ground plate 82 may be lowered into interior cavity 91 of conductive shell 78, as shown by arrow 112 of
A dielectric substrate such as a plastic substrate or printed circuit board (not shown in
As shown in
Ring-shaped conductive trace 96 may form terminal 36, ring-shaped conductive trace 94 may form terminal 34, and conductive trace 92 may form circuit node 38 of bimodal impedance terminator 20 (
Ground plate 82 may include holes or openings such as openings 104, 106, and 108. Opening 104 may be aligned with the center of ring-shaped conductive trace 96. Opening 106 may be aligned with the center of ring-shaped conductive trace 100. Opening 108 may be aligned with the center of ring-shaped conductive trace 94. Conductive pins such as conductive pins 84, 86, and 88 may be placed within openings 108, 104, and 106, as shown by arrow 110 of
Conductive pins 84, 86, and 88 may each have first ends 116 with a first diameter and second ends 114 with a second diameter greater than the first diameter. First ends 116 may pass through openings 104, 106, and 108 whereas second ends 114 may be too large to pass through ring-shaped conductive traces 96, 100, and 94. For example, first end 116 of conductive pin 86 may pass through ring-shaped conductive trace 96 and opening 104. Second end 114 of conductive pin 86 may rest on ring-shaped conductive trace 96. Conductive adhesive, solder, and/or welds may be used to mechanically and galvanically connect second end 114 of conductive pin 86 to ring-shaped conductive trace 96. In this way, end 116 of conductive pin 86 may form contact 60 whereas end 114 of conductive pin 86 forms contact 58 of connector 48 (
Similarly, first end 116 of conductive pin 84 may pass through ring-shaped conductive trace 94 and opening 108. Second end 114 of conductive pin 84 may rest against ring-shaped conductive trace 94. Conductive adhesive, solder, and/or welds may be used to mechanically and galvanically connect second end 114 of conductive pin 84 to ring-shaped conductive trace 94. In this way, end 116 of conductive pin 84 may form contact 64 whereas end 114 of conductive pin 84 forms contact 52 of connector 48 (
In the example of
Forming bimodal impedance terminator 20 within one or both of connectors 48A and 48B may optimize the immunity of data path 14 to common-mode electromagnetic excitations. Consider, for example, a transmission line equivalent circuit model of a simplest-case network 12 that is provided with only two internal nodes 161 and that is subject to a common-mode external electromagnetic disturbance.
Common-mode voltage sources 136 are coupled to transmission lines 132 and 134 and inject a common-mode voltage VS at location X=0 along the length of the transmission lines. Common-mode voltage VS may simulate a common-mode external electromagnetic disturbance on data path 14. Transmission lines 132 and 134 in model 130 each exhibit minor imbalances in per-unit-length inductance and capacitance. For example, transmission lines 132 and 134 may each exhibit per-unit-length self-capacitance C, per-unit-length mutual-capacitance CM, per-unit-length capacitance imbalance of ΔC, per-unit-length self-inductance L, per-unit-length mutual-inductance LM, and per-unit-length inductance imbalance ΔL. The ratio of per-unit-length capacitance imbalance ΔC to per-unit-length self-capacitance C (e.g., ΔC/C) and the ratio of per-unit-length inductance imbalance ΔL to per-unit-length self-inductance L (e.g., ΔL/L) may each be on the order of 10−3 or smaller. If transmission lines 132 and 134 are perfectly balanced, per-unit-length capacitance imbalance of ΔC and per-unit-length inductance imbalance of ΔL are each equal to zero, and the differential-mode voltages and current are all equal to zero.
Model 130 includes two impedance terminator equivalent circuits 138 and 140 at opposing ends of transmission lines 132 and 134. Impedance terminator equivalent circuit 138 includes impedance Za coupled between transmission line 132 and circuit node 142, impedance Za coupled between transmission line 134 and circuit node 142, and impedance Zb,1 coupled between circuit node 142 and ground 32. Impedance terminator equivalent circuit 140 includes impedance Za coupled between transmission line 132 and circuit node 144, impedance Za coupled between transmission line 134 and circuit node 144, and impedance Zb,2 coupled between circuit node 144 and ground 32.
Assuming that the transmission lines are not perfectly balanced, the modal conversion factor ζ of model 130 is given by equation 7.
ζ=0.5*MAX{|ξ−η|,|ξ+η|} (7)
In equation 7, MAX{ } is the maximum value operator that outputs the greater of its inputs |ξ−η| and |ξ+η|, ξ is a transmission line ratio defined by equation 8, and η is a transmission line ratio defined by equation 9.
ξ=(C*ΔL−L*ΔC)/(C*LM−L*CM) (8)
η=(CM*ΔL−LMΔC)/(C*LM−L*CM) (9)
The differential voltage ΔV(−l1) at left end 154 of model 130 (e.g., between circuit nodes 146 and 148 of
ΔV(−l1)≅ζ*|[1−Γe,2*exp(−2*j*β*l2)]*[1+Γe,1]|*Vs/Δe (10)
ΔV(l2)≅|[1−Γe,1*exp(−2*j*β*l1)]*[1+Γe,2]|*Vs/Δe (11)
In equations 10 and 11, exp( ) is the exponential operator (e.g., Euler's number raised to the power of the argument of exp( )), Γe,2 is the reflection coefficient of transmission lines 132 and 134 at location X=l2, defined by equation 12, Γe,1 is the reflection coefficient of transmission lines 132 and 134 at location X=−l1, defined by equation 13, β is the common-mode propagation constant of model 130, given by equation 12, and Δe is a denominator factor, defined by equation 15. Common-mode propagation constant β may sometimes referred to as even-mode propagation constant β.
Γe,1=(Za+2*Zb,1−2*Zcomm)/(Za+2*Zb,1+2*Zcomm) (12)
δe,2=(Za+2*Zb,2−2*Zcomm)/(Za+2*Zb,2+2*Zcomm) (13)
β=ω*SQRT([L+LM]*[C−CM]) (14)
Δc=1−Γe,1*Fe,2*exp(−2*j*β*[l1+l2]) (15)
In equations 12-15, Zcomm is the common-mode impedance of the transmission lines (e.g., as given by equation 2) and w is the angular frequency of signals on the transmission lines. As one example (e.g., in a scenario where data path 14 is implemented using an Ethernet cable), L≅9.86854*10−7 (H/m), LM≅7.29226*10−7 (H/m), ΔL≅2.0*10−10 (H/M), C≅3.94471*10−11 (F/m), CM≅3.25842*10−11 (F/m), and ΔC≅1.9*10−14 (F/m), Zdiff≅119.6 ohms, and Zcomm≅250 ohms. This example is merely illustrative and, in general, the differential signal lines may have any desired inductive and capacitive characteristics (e.g., as determined by the characteristics and arrangement of the cabling used to implement data path 14).
At conditions where Δe approaches zero, differential voltages ΔV(−l1) and ΔV(l2) will peak (e.g., as shown by equations 10 and 11). However, as shown by equations 10, 11, and 15, if one or both of the reflection coefficients δe,1 and Γe,2 drop to zero, peaks in differential voltages ΔV(−l1) and ΔV(l2) will vanish. As described above (e.g., as shown by equation 6), terminating data path 14 using one or more bimodal impedance terminators 20 will greatly reduce the magnitude of the reflection coefficients, thereby reducing or minimizing any peaks in differential voltages ΔV(−l1) and ΔV(l2).
Consider one example in which impedance Za of model 130 is set to 0.5*Zdiff (e.g., where Zdiff is the differential mode impedance given by equation 1) and the same termination scheme is used at both ends 154 and 156 of model 130 (e.g., ends 21 and 23 of data path 14, respectively, as shown in
Curve 162 of graphs 158 and 160 plots the differential voltage in scenarios where a single 120-ohm resistor is coupled between the differential signal lines. The infinite common-mode impedance in this scenario may cause excessive signal reflections at both ends of the data path and may leave the data path susceptible to external common-mode noise. This noise may generate relatively large signal peaks 168 in the differential voltage, which can generate an excessive number of errors in the data conveyed over the data path.
Dark curve 164 of graphs 158 and 160 plots the differential voltage in scenarios where a split termination scheme is used (e.g., where a shunting capacitance Ct is coupled to one differential signal line through a first 60-ohm resistor and to the other differential signal line through a second 60-ohm resistor without resistor Rg of
Dotted curve 166 of graphs 158 and 160 plots the differential voltage in scenarios where bimodal impedance terminator 20 is coupled to both ends of the data path (e.g., where bimodal impedance terminator 20-1 is coupled to end 21 and bimodal impedance terminator 20-2 is coupled to end 23 of data path 14 as shown in
The example of
Curve 176 of graphs 172 and 174 plots the differential voltage in scenarios where a bimodal impedance terminator 20 is only coupled to left end 21 of differential signal lines 26H and 26L of
As shown by curves 176 and 178, bimodal impedance terminator 20 will still reduce peaks in differential voltage when coupled to only a single end of the data path relative to scenarios where a single 120-ohm resistor is used to terminate both ends (e.g., as shown by curve 162 of
The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.
