IEEE 370-2020 pdf download

IEEE 370-2020 pdf download.IEEE Standard for Electrical Characterization of Printed Circuit Board and Related lnterconnects at Frequencies up to 50 GHz.
The 2X-Thru shall be routed on the same PCB layer as the test fixture traces.
— The 2X-Thru shall incorporate the same layer transitions and test point launch as the test fixture.
— With the measurement reference plane set at the coaxial test point, the insertion loss of the 2X-Thru shall meet the requirements of 4.3.4 for insertion loss.
With the measurement reference plane set at the coaxial test point, the return loss of the 2X-Thru shall meet the requirements of 4.3 .5 for return loss.
The 2X-Thru and test fixture traces should be oriented in the same direction on the PCB panel as illustrated in Figure 6.
4.2.4 Mixed-mode de-embedding
The 2X-Thru method described in 4.2.3 is applicable to mixed-mode (differential) de-embedding structures as well, except that differential ports are used instead of single-ended ports.
However, differential transmission lines that have intentional coupling require additional design considerations. For example, test fixture traces for differential dc-embedding have areas that are transitioning from single-ended to differential routing due to the physical size of the coaxial connectors or probing footprint. Ensure that the transition from a single-ended to coupled transmission line does not cause large return loss that may degrade dc-embedded results. This issue is addressed in 6.4.
4.2.5 Single-ended fixture crosstalk
Fixture crosstalk may remain in the measured data after calibrating or dc-embedding. and measured crosstalk can be larger than DUT crosstalk. If crosstalk is a parameter to be measured and the fixture crosstalk cannot be dc-embedded, a bdoglegi structure shall be included in the fixture to measure the trace- to-trace fixture crosstalk directly. Those results should then be compared against the total measured crosstalk to determine whether the fixture crosstalk is large enough to compromise the results. A dogleg structure for measuring trace-to-trace crosstalk is designed as follows (see Moon et al. ‘Fixture” [B24J):
— Pick one pair of traces in close proximity, the worst case (smallest spacing).
— If the input and output side traces are on the same wiring plane, remove the DUT portion of the test board design and connect the traces together, as shown in Figure 8. If the input and output side traces are not on the same routing layer, copy the input side traces and mirror them to create the output side traces for the first layer, and connect them directly to the input side traces. Then copy the output side traces from the second layer to create the input side traces for the second layer, and connect them directly together. This will create two dogleg structures.
— Construct the trace lengths of the dogleg to be the same as the 2X-Thru length. Terminate all unused ports with 50 Ohm loads when measuring crosstalk. For example, when the far end crosstalk (FEXT) is measured from P1 to P2’, terminate ports P2 and P1’.
Terminate all unused ports when measuring crosstalk.
4.3.3 FER compliance
The class of a fixture may vary by frequency and DUT performance. For example, a fixture measured from 10 MHz to 50 GHz with 10 MHz steps may fail a Class A requirement at 10 GHz and fail a Class B requirement at 40 GHz, and fail a Class C requirement at 50 GHz. That fixture is deemed Class A compliant for frequencies below 10 GHz, Class B for frequencies below 40 GHz, and Class C for frequencies below 50 GHz. A fixture is deemed non-conforming for all frequencies higher than the frequency of its first class C failure.
Throughout this document, insertion loss is expressed as a negative value in dB, to specify the amount of attenuation.
4.3.4 FERI: Insertion loss of 2X-Thru
— Class A minimum: —10 dB at all frequencies of interest Class B minimum: —15 dB at all frequencies of interest
— Class C minimum: —15 dB at all frequencies of interest
Justification: As fixture insertion loss increases, dc-embedding becomes more unreliable and unstable.
4.3.5 FER2: Return loss of 2X-Thru
— Class A maximum: —20 dB at all frequencies of interest
— Class B maximum: —10 dB at all frequencies of interest
— Class C maximum: —6 dB at all frequencies of interest
Justification: Return loss values of fixtures above this value result in unreliable calibration or removal. This specification is for single-ended, differential, and common-mode return loss.