Signaling over RC-dominated transmission lines
The disclosure provides a signaling link that overcomes or at least reduces the limitations of RC-dominated signaling wires, improving both the bandwidth and the power consumption of signaling circuits. Both an AC and a DC signaling link are disclosed. In one example, a signaling link is provided that includes: (1) a transmitter including a passive equalizer, (2) an over-terminated receiver, and (3) a lossy channel having a first end connected to the passive equalizer and a second end connected to the receiver, wherein the lossy channel has a channel characteristic impedance that is lower than a terminating impedance of the passive equalizer and a termination impedance of the receiver.
1. A signaling link, comprising:
a transmitter including a passive equalizer;
an over-terminated receiver; and
a lossy channel having a first end connected to the passive equalizer and a second end connected to the receiver, wherein the lossy channel has a channel characteristic impedance that is lower than a terminating impedance of the passive equalizer and a termination impedance of the receiver.
2. The signaling link as recited in claim 1 , wherein the lossy channel is an RC dominated communications channel having an attenuation of about 3 dB or greater at Nyquist frequency.
3. The signaling link as recited in claim 1 , wherein the lossy channel is an RC dominated communications channel having an attenuation that reduces reflections on the channel to a negligible signal voltage.
4. The signaling link as recited in claim 1 , wherein the over-terminated receiver includes receiving circuitry having an amplifier connected to a resistive terminator.
5. The signaling link as recited in claim 4 , wherein the receiving circuitry further includes at least one overall feedback resistor connected in parallel with the resistive terminator and the amplifier.
6. The signaling link as recited in claim 4 , wherein the resistive terminator is a resistive Thevenin termination.
7. The signaling link as recited in claim 4 , wherein the resistive terminator is a Cherry-Hooper amplifier.
8. The signaling link as recited in claim 4 , wherein the resistive terminator is a transimpedance amplifier (TIA).
9. The signaling link as recited in claim 1 , wherein the passive equalizer includes one or more equalizing capacitors.
10. The signaling link as recited in claim 9 , wherein the passive equalizer further includes one or more equalizing resistors coupled in parallel with the one or more equalizing capacitors.
11. The signaling link as recited in claim 1 , wherein the signaling link is a short reach link.
12. An electrical system, comprising:
a signaling link;
a first circuit connected to a first end of the signaling link; and
a second circuit connected to a second end of the signaling link, wherein the signaling link includes:
a transmitter having a passive equalizer network;
an over-terminated receiver; and
a lossy channel having a first end connected to the passive equalizer network and a second end connected to the receiver, wherein the lossy channel has a channel characteristic impedance that is lower than terminating impedances of the passive equalizer network and the receiver.
13. The system as recited in claim 12 , wherein the first circuit is a processor and the second circuit is a memory.
14. The system as recited in claim 12 , wherein the first circuit is a processor and the second circuit is a different processor.
15. The system as recited in claim 12 , wherein the first circuit and the second circuit are located on a single chip.
16. The system as recited in claim 15 , wherein the lossy channel is constructed of a metal that is not copper.
17. The system as recited in claim 12 , further comprising an interposer that includes more than one of the signaling link, wherein the first circuit is a first chip, the second circuit is a second chip, and the interposer connects the first chip to the second chip.
18. A multi-chip module, comprising:
multiple chips; and
a connector that couples one or more of the multiple chips to at least a different one of the one or more of the multiple chips, wherein the connector includes one or more signaling links and at least one of the one or more signaling links includes:
a transmitter having a passive equalizer;
an over-terminated receiver; and
a lossy channel having a first end connected to the passive equalizer and a second end connected to the receiver, wherein the lossy channel has a channel characteristic impedance that is lower than terminating impedances of the passive equalizer and the receiver.
19. The multi-chip module as recited in claim 18 , wherein the connector is an interposer.
20. The multi-chip module as recited in claim 19 , wherein the lossy channel has a length within a range of 1 to 10 millimeters.
21. A high bandwidth memory system, comprising:
one or more memories;
one or more circuits; and
a connector that connects at least one of the one or more memories to at least one of the one or more circuits, wherein the connector includes at least one signaling link that includes:
a transmitter including a passive equalizer;
an over-terminated receiver; and
a lossy channel having a first end connected to the passive equalizer and a second end connected to the receiver, wherein the lossy channel has a channel characteristic impedance that is lower than a terminating impedance of the passive equalizer and a termination impedance of the receiver.
22. The high bandwidth memory system as recited in claim 21 , wherein the connector is an interposer.
23. An AC signaling link, comprising:
a transmitter including one or more equalizing capacitors;
an over-terminated receiver having an amplifier connected to a resistive terminator and at least one overall feedback resistor connected in parallel with the resistive terminator and the amplifier; and
a lossy channel having a first end connected to the one or more equalizing capacitors and a second end connected to the receiver, wherein the lossy channel has a channel characteristic impedance that is lower than a terminating impedance of the one or more equalizing capacitors and a termination impedance of the receiver.
24. The AC signaling link as recited in claim 23 , wherein the resistive terminator is a transimpedance amplifier (TIA).