System and method for standby power reduction in a serial communication system

Abstract

In a serial communication system having a device including a receiver detection module, this specification is directed to systems and methods for selectively reducing the power consumed by the receiver detection module, preferably when the device is operating in a low power mode. In some embodiments, a signal detection module is configured to receive a control signal from the transmitter of a device at the other end of the communications link to control the operation of the receiver detection module. The control signal may be in-band or may be transmitted on a sideband of the serial link.

1 . A communication system comprising:
 a transmitter;   a receiver including a receiver detection module and a power module; and   a serial link between the transmitter and the receiver,   a signal detection module configured to sense a control signal carried on the serial link and operatively coupled to the power module,   wherein the receiver detection module is configured to be operable during a power save state of the serial link to determine an operational condition of the serial link and wherein the power module is configured to selectively operate the receiver detection module in a low power mode during the power save state of the serial link on the basis of the control signal.   
     
     
         2 . The communications system of  claim 1 , wherein the low power mode of the receiver detection module is a duty cycle mode. 
     
     
         3 - 4 . (canceled) 
     
     
         5 . The communication system of  claim 1 , wherein the signal detection module is configured to detect a common mode signal carried on the serial link. 
     
     
         6 . The communication system of  claim 1 , wherein the signal detection module is configured to detect a differential mode signal carried on the serial link. 
     
     
         7 . The communication system of  claim 1 , wherein the serial link comprises a PCIe link. 
     
     
         8 . The communication system of  claim 1 , wherein the receiver detection module comprises electric idle detection logic. 
     
     
         9 . The communication system of  claim 8 , wherein the power module is configured to disable the electric idle detection logic to selectively operate the receiver detection module in the low power mode. 
     
     
         10 . A serial communication system comprising a host having a transmitter and a client having a receiver, wherein the transmitter and the receiver are configured to communicate through transfer of differential data signals over a link using a protocol that specifies at least one active state and at least one power save state and the host is configured to transmit a control signal in-band, a receiver detection module in the client configured be operable during the power save state to determine an operational state of the link, a signal detection module in the client configured to sense the control signal and a power module in the client configured to selectively operate the receiver detection module in low power mode on the basis of the control signal from the host. 
     
     
         11 . The serial communication system of  claim 10 , wherein the receiver detection module comprises electric idle detection logic and wherein the low power mode of the receiver detection module disables the electric idle detection logic. 
     
     
         12 . The serial communication system of  claim 11  wherein the serial communication system is a PCIe system and wherein the active state of the serial communication system is a L0 link state and the power save state of the serial communication system is a L1 link state. 
     
     
         13 - 14 . (canceled) 
     
     
         15 . The serial communication system of  claim 10 , wherein the control signal comprises an in-band common mode signal. 
     
     
         16 . The serial communication system of  claim 10 , wherein the control signal comprises an in-band differential mode signal. 
     
     
         17 . The serial communication system of  claim 10 , wherein the power module selectively operate the receiver detection module in low power mode by operating the receiver detection module in a duty cycle mode. 
     
     
         18 . A method for standby power reduction in a serial communication system having a transmitter and receiver, communicating over a serial data link, comprising
 operating the serial data link in a power save state;   sending an in-band control signal with the transmitter;   detecting the control signal in-band on the serial data link; and   selectively operating a receiver detection module of the receiver configured to determine an operational condition of the serial data link in a low power mode while the serial data link is in the power save state on the basis of the control signal.   
     
     
         19 . The method of  claim 18 , wherein the serial data link comprises a PCIe link, wherein the power save state of the serial data link is an L1 state, and wherein the low power mode comprises disabling electrical idle detection logic in the receiver detection module. 
     
     
         20 - 22 . (canceled) 
     
     
         23 . The method of  claim 18 , wherein detecting the control signal comprises detecting a common mode signal on the serial data link. 
     
     
         24 . The method of  claim 18 , wherein detecting the control signal comprises detecting a differential mode signal on the serial data link.