Intel 820E manual Impedance Calculation Tools, Field Solver vs. Zcalc

Intel® 820E Chipset

R

Figure 98. Microstrip (a) and Stripline (b) Cross Section for 28 Ω Trace

a) Microstrip cross section for 28-Ωtrace

10 mils		18 mils
	6 mils

G	S	G
	4.5 mils

2.1 mils

b) Stripline cross section for 28-Ωtrace

			1.2 mils
6 mils	13.5 mils		7 mils
G	5 mils
	S	1.2 mils	G
	5 mils
			1.2 mils
			x-section_28trace

Note: Do not forget ground floods and stitching.

5.1.6.Impedance Calculation Tools

3D field solvers, such as those by HP, Ansoft, Sonnet, and Polar, are most accurate when calculating the impedance. Z calculators based on equations (zcalc) also are fairly accurate. The differences are listed in the following table.

Table 62. 3D Field Solver vs. ZCALC

	#1	#2	#3	#4	#5	#6
H	4.5	4.5	4.2	4.8	4.5	4.5
W	18	18	18	18	17	19
W1	18.1	18.1	18.1	18.1	17.1	19.1
T	1.4	2.8	1.4	1.4	1.4	1.4
ε r	4.5	4.5	4.5	4.5	4.5	4.5
Z0 (3D)	29.0	28.4	27.6	30.4	30.2	27.9
Z0 (zcalc)	29.1	28.7	27.7	30.4	30.2	28.0

180 Design Guide