Dual-duplex link with independent transmit and receive phase adjustment
A Serializer/Deserializer (SERDES) circuit is disclosed. The circuit includes an input/output (I/O) pad for coupling to a duplex SerDes link. An adjustable delay line provides a first component of a relative phase between a receive signal sampling point and a transmit echo signal. A second delay circuit generates a second component of the relative phase. A timing relationship between the receive signal sampling point and the transmit echo signal is based on the sum of the first and second components.
1. A Serializer/Deserializer (SERDES) circuit comprising:
an input/output (I/O) pad for coupling to a duplex SerDes channel;
an adjustable delay line to provide a first component of a relative phase between a far-end received signal and a near-end transmit signal, wherein the first component comprises an applied adjustable delay;
a phase adjustment circuit to generate a second component of the relative phase; and
wherein a timing relationship between the receive signal phase and the transmit signal phase is based on the sum of the first component and the second component.
2. The SERDES circuit according to claim 1 , wherein the adjustable delay line includes:
multiple inductor-capacitor (LC) delay cells formed on-chip, each LC delay cell having a variable delay parameter.
3. The SERDES circuit according to claim 1 , wherein the adjustable delay line includes:
multiple inductor-capacitor (LC) delay cells formed on-chip, each LC delay cell having a fixed delay parameter and switchably coupled to the receiver sampler.
4. The SERDES circuit according to claim 3 , wherein each LC delay cell is switchably coupled to the receiver sampler and a transmitter driver.
5. The SERDES circuit according to claim 1 , wherein the SERDES circuit is configured as a slave device to communicate with a master device, and wherein data transmit and receive operations are synchronized with a timing signal generated by the master device.
6. The SERDES circuit according to claim 5 , wherein the adjustable delay line is selectively enabled to extend a range of delay for the master device.
7. The SERDES circuit according to claim 1 , wherein the SERDES circuit is configured as a master device to communicate with a slave device, and wherein data transmit and receive operations are synchronized with a timing signal generated by the master device.
8. A method of operation in a Serializer/Deserializer (SERDES) circuit, the method comprising:
providing a first component of a relative phase between a far-end received signal phase and a near-end transmit signal phase, wherein the providing the first component comprises applying an adjustable delay to achieve the first component of the relative phase;
generating a second component of the relative phase; and
wherein a timing relationship between the far-end received signal and the near-end transmit signal is based on summing the first component and the second component.
9. The method according to claim 8 , wherein applying an adjustable delay comprises:
varying a delay parameter for each of multiple inductor-capacitor (LC) delay cells formed on-chip.
10. The method according to claim 8 , wherein applying an adjustable delay comprises:
setting a fixed delay parameter for each of multiple inductor-capacitor (LC) delay cells formed on-chip; and
switchably coupling selected LC delay cells to a receiver sampler.
11. The method according to claim 10 , wherein applying an adjustable delay comprises:
switchably coupling selected LC delay cells to a transmitter driver.
12. The method according to claim 8 , further comprising:
configuring the SERDES circuit as a slave device for communicating with a master device; and
synchronizing data transmit and receive operations with a timing signal generated by the master device.
13. The method according to claim 12 , wherein the method further comprises:
selectively adjusting the relative phase on the slave device to extend a range of delay for the master device.
14. The method according to claim 8 , further comprising:
configuring the SERDES circuit as a master device for communicating with a slave device;
generating a timing signal on the master device; and
synchronizing data transmit and receive operations on the master device and the slave device with the timing signal.
15. A Serializer/Deserializer (SERDES) link comprising:
a signaling channel;
a first SERDES circuit coupled to a first end of the signaling channel; and
a second SERDES circuit coupled to a second end of the signaling channel to communicate with the first SERDES circuit;
wherein the second SERDES circuit includes
an adjustable delay line to provide a first component of a relative phase between a far-end received signal and a near-end transmit signal, wherein the first component comprises an applied adjustable delay;
a phase adjustment circuit to generate a second component of the relative phase; and
wherein a timing relationship between the received signal and the transmit signal is based on the sum of the first component and the second component.
16. The SERDES link according to claim 15 , wherein:
the first SERDES circuit is configured as a slave device;
the second SERDES circuit is configured as a master device; and
wherein data transmit and receive operations for both the master device and the slave device are synchronized to a timing signal generated by the master device.
17. The SERDES link according to claim 15 , wherein the adjustable delay line includes:
multiple inductor-capacitor (LC) delay cells formed on-chip, each LC delay cell having a variable delay parameter.
18. The SERDES link according to claim 15 , wherein the adjustable delay line includes:
multiple inductor-capacitor (LC) delay cells formed on-chip, each LC delay cell having a fixed delay parameter and switchably coupled to the receiver sampler.
19. The SERDES link according to claim 18 , wherein each LC delay cell is switchably coupled to the receiver sampler and a transmitter driver.