Question about SAS 12G coefficient's adjustment rules

Yupengfei (B) yu.yupengfei at
Tue Mar 17 03:50:55 PDT 2015

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Hi All,

I have questions needing your help.

In SAS-3R06’s Figure 131 -- “Minimum and maximum coefficient ranges at
maximum peak to peak voltage”,

it defines the minimum range and maximum range of C1 and C3 with different

Question 1:

Whether the value of C1 and C3 is the total value surrounding by the purple
solid line when Vpp_noeq = 1200mv?

If so, does it mean the value of C1 and C3 in purple solid line satisfied
equation “VMA>=80mv” when Vpp_noeq=1200mv?

Question 2:

Do we need a constraint like “C2-|C1|-|C3|>=Fixed Value” to ensure
“VMA>=80mv” when Vpp_noeq is variable between 850mv and 1200mv?

If yes, when we constraint “C3>=-0.3” and “C1>=-0.15”(the range
surrounding by the red dotted line shown in Figure 131, which is the minimum
range we should support), we do not need the constraint
“C2-|C1|-|C3|>=Fixed Value” or any other constraint of C2 to ensure the
minimum value of VMA, right?

Best Regards,

Pengfei Yu


华为技术有限公司 Huawei Technologies Co., Ltd.




Mobile: 18665362797

Email: yu.yupengfei at

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Huawei Technologies Co., Ltd.

Bantian, Longgang District,Shenzhen 518129, P.R.China





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发件人: Harvey Newman [mailto:harvey.newman at]

发送时间: 2015年3月7日 6:43

收件人: Yupengfei (B)

抄送: t10 at; Ningzuolin; Guojian (F); Yangjunbin (Jim, HS)

主题: Re: Question about SAS 12G coefficient's adjustment rules

Hi Pengfei,

Your equations are not using the designations we have in our spec but the
point is the coeffients are negative, a decrement causes the value to go more
negative causing a larger amount of equalization.

c1-0.1=-0.3 is the correct answer.


Harvey Newman

Avago Technologies

On Fri, Mar 6, 2015 at 12:00 AM, Yupengfei (B)
<yu.yupengfei at> wrote:

Hi Harvey

OK, thanks, and I have one more question.

As far as I know, c1/ c2/ c3 is equalization coefficient of TX direction ,
used in 12G TX_Training and both c1 and c3 are zero or negative:

V_outn=(v_inn+1*c3)+ (v_inn*c2)+ (v_inn-1*c1)

So I want to ask, when we receive a decrement request of c3 or c1 in TTIU
during 12G TX_Training,  we should decrease its absolute value or increase
its absolute value?

For example, now our coefficient is :

c1=-0.2 ;    c2=0.7  ;	   c3=-0.1 ;

when we receive a decrement request of c1 , what’s the value of c1 now?

(we assume the decrement is 0.1 in one request.)





Which is correct?

Best Regards,

Pengfei Yu

Hi Pengfei,

SAS 12G Tx training does not have any such requirement. The transmitter
coefficients are free to be adjusted by the receiver in any way it wishes.
This includes an over all decrease in amplitude if it so desires.


Harvey Newman

Avago Technologies

On Wed, Mar 4, 2015 at 10:57 PM, Yupengfei (B)
<yu.yupengfei at> wrote:

Hi all,

I would like to know, during the process of SAS 12G TX_TRAINING, is there any
rules like PCI-E:

“The sum of C1, C2, and C3 should keep a fixed value (|C-1|+|C+1|+C0 =

If there is any, please specify the source in the agreement.

Thank you!

Best regards,

Pengfei Yu


Harvey Newman

Avago Technologies

(408) 433-4028<tel:%28408%29%20433-4028>


Harvey Newman

Avago Technologies

(408) 433-4028

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