Seagate ST3400755SS manual = -5,437dB

A combination of a zero-length test load and the transmitter compliance transfer function (TCTF) test load methodology is used for the specification of transmitter characteristics. This methodology specifies the trans- mitter signal at the test points on the required test loads. The transmitter uses the same settings (e.g., pre- emphasis, voltage swing) with both the zero-length test load and the TCTF test load. The signal specifications at IR are met under each of these loading conditions.

The TCTF is the mathematical statement of the transfer function through which the transmitter shall be capable of producing acceptable signals as defined by a receive mask. The transmission magnitude response of the TCTF in dB is given by the following equation for 1.5 Gbps:

S21

= –20⋅ log10 (e) ⋅ ((6, 5 ⋅ 10–6⋅ f0, 5) + (2, 0 ⋅ 10–10⋅ f) + (3, 3 ⋅ 10–20⋅ f2 )) dB

for 50 MHz < f < 1.5 GHz, and:

S21

= –5,437dB

for 1.5 GHz < f < 5.0 GHz, where:

a) f is the signal frequency in hertz.

The transmission magnitude response of the TCTF in dB is given by the following equation for 3.0 Gbps:

S21

= –20⋅ log10(e) ⋅ ((6, 5 ⋅ 10–6⋅ f0, 5) + (2, 0 ⋅ 10–10⋅ f) + (3, 3 ⋅ 10–20⋅ f2)) dB

for 50 MHz < f < 3.0 GHz, and:

S21

= –10,884dB

for 3.0 GHz < f < 5.0 GHz,

where f is the signal frequency in hertz.

The TCTF is used to specify the requirements on transmitters that may or may not incorporate pre-emphasis or other forms of compensation. A compliance interconnect is any physical interconnect with loss equal to or greater than that of the TCTF at the above frequencies that also meets the ISI loss requirements shown in fig- ure 35 and figure 36.

Compliance with the TCTF test load requirement is verified by measuring the signal produced by the transmit- ter through a physical compliance interconnect attached to the transmitter.

Compliance with the zero-length test load requirement verified by measurement made across a load equiva- lent to the zero-length load shown in figure 34.

For both test load cases, the transmitter delivers the output voltages and timing listed in table 15 at the desig- nated compliance points. The default mask is IR for intra-cabinet TxRx connections. The eye masks are shown in 9.5.2.1.

Figure 33 shows the compliance interconnect test load.

Tx+

TCTF

Tx-

10 nF	50 ohm
Probe
points
10 nF	50 ohm

SAS internal connector

Figure 33. Compliance interconnect test load

Cheetah NS SAS Product Manual, Rev. B 63