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Design >> High-Speed I/O Design >> termination resistance trimming
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Message started by neeru on Jun 9^th, 2014, 10:07pm

Title: termination resistance trimming
Post by neeru on Jun 9^th, 2014, 10:07pm

Hi,
I have notived in several PHY designs that the termination impedance is 50ohms. But there are usually digital bits to tune them.
How does the tuning happen in production ICS?
I guess they can't characterize each chip......

Thanks in advance

Title: Re: termination resistance trimming
Post by raja.cedt on Jun 9^th, 2014, 11:59pm

that is why people use digital/Analog Auto calibration circuitry..

Title: Re: termination resistance trimming
Post by loose-electron on Jun 24^th, 2014, 3:12pm

http://www.teradyne.com/

http://www.ltxc.com/

and many others

Title: Re: termination resistance trimming
Post by bharat on Mar 23^rd, 2015, 6:10am

that is why people use digital/Analog Auto calibration circuitry..

How is that calibration done, by using some external resistance ? I have seen impedance calibration for TX but not for RX.

Thanks

Title: Re: termination resistance trimming
Post by raja.cedt on Mar 24^th, 2015, 4:43am

They do for both TX and RX. All standards has limit on S11,S22..very difficult to meet if you don't have some kind of calibration. Not only from S11,S22 point of view but also from TX driver swing and current point of view also termination is imp...
Some people does this with a tester burning E-fuse which saves some initial bring up time.

Raj!