IEEE Circuits and Systems Magazine - Q3 2020 - 38

Alternatively, load matching methods can be used.
Some examples are shown in Fig. 6(b)-(d) [1]. Load
matching is typically connected in shunt to reduce the
effective load impedance closer to Z0.
IV. Basic PCB Structures
A. Transitions
When a microstrip transitions to a different layer (to a
microstrip, a stripline, or a CPW), the impedance might
be disturbed, which can deteriorate the quality of the
signal passing through the line.

Solid Ground

For a microstrip transitioning to another microstrip
or to a stripline, it is essential to ensure a proper return path to minimize any disturbance in the impedance [25]. This can be achieved by adding a via between the reference grounds of the first line and the
second line, as shown in Fig. 7(a). This via is part of the
ground return path.
The same concept can be applied to differential
lines. Ideally, the ground rwhoeturn path in differential lines is not necessary. Any mismatch between the
two lines, however, results in a common mode current.
As a result, when transitioning differential lines from

Discontinuous Ground

1

2

3

4

Avoid Discontinuity

With Capacitor

(c)

(d)

Top Layer Conductor

(a)

(b)
0

-1

Reflection S11 (dB)

Transmission S21 (dB)

0

-2
-3

Solid Ground
Discontinuous Ground
Avoid Discontinuity
With Capacitor

-4
-5
-6

2

4
6
Frequency (GHz)

8

-10
-20
-30
-40

10

2

(e)
Backward Crosstalk S31 (dB)

Forward Crosstalk S41 (dB)

-10
-20
-30

2

4
6
Frequency (GHz)

8

10

8

10

(f)

0

-40

4
6
Frequency (GHz)

8

10

(g)

-5
-10
-15
-20
-25
-30
-35

2

4
6
Frequency (GHz)
(h)

Figure 3. (a) A solid ground return path below a straight line gives the best performance. (b) A discontinuous ground return path
results in loss, mismatch, coupling, and radiation. (c) Re-routing lines around the discontinuity alleviates the problems from
the discontinuity. (d) The discontinuity can also be resolved by adding a capacitor to provide an ac low-impedance return path.
(e)-(h) Simulated transmission, reflection, forward crosstalk, and backward crosstalk for the scenarios in (a)-(d), respectively.
(Simulations are based on: substrate: RO-4350B, thickness: 20 mil, line width: 0.925 mm, distance between the lines 1.2 mm,
discontinuity dimensions: 9 mm × 3 mm.)
38 	

IEEE CIRCUITS AND SYSTEMS MAGAZINE 		

THIRD QUARTER 2020



IEEE Circuits and Systems Magazine - Q3 2020

Table of Contents for the Digital Edition of IEEE Circuits and Systems Magazine - Q3 2020

Contents
IEEE Circuits and Systems Magazine - Q3 2020 - Cover1
IEEE Circuits and Systems Magazine - Q3 2020 - Cover2
IEEE Circuits and Systems Magazine - Q3 2020 - Contents
IEEE Circuits and Systems Magazine - Q3 2020 - 2
IEEE Circuits and Systems Magazine - Q3 2020 - 3
IEEE Circuits and Systems Magazine - Q3 2020 - 4
IEEE Circuits and Systems Magazine - Q3 2020 - 5
IEEE Circuits and Systems Magazine - Q3 2020 - 6
IEEE Circuits and Systems Magazine - Q3 2020 - 7
IEEE Circuits and Systems Magazine - Q3 2020 - 8
IEEE Circuits and Systems Magazine - Q3 2020 - 9
IEEE Circuits and Systems Magazine - Q3 2020 - 10
IEEE Circuits and Systems Magazine - Q3 2020 - 11
IEEE Circuits and Systems Magazine - Q3 2020 - 12
IEEE Circuits and Systems Magazine - Q3 2020 - 13
IEEE Circuits and Systems Magazine - Q3 2020 - 14
IEEE Circuits and Systems Magazine - Q3 2020 - 15
IEEE Circuits and Systems Magazine - Q3 2020 - 16
IEEE Circuits and Systems Magazine - Q3 2020 - 17
IEEE Circuits and Systems Magazine - Q3 2020 - 18
IEEE Circuits and Systems Magazine - Q3 2020 - 19
IEEE Circuits and Systems Magazine - Q3 2020 - 20
IEEE Circuits and Systems Magazine - Q3 2020 - 21
IEEE Circuits and Systems Magazine - Q3 2020 - 22
IEEE Circuits and Systems Magazine - Q3 2020 - 23
IEEE Circuits and Systems Magazine - Q3 2020 - 24
IEEE Circuits and Systems Magazine - Q3 2020 - 25
IEEE Circuits and Systems Magazine - Q3 2020 - 26
IEEE Circuits and Systems Magazine - Q3 2020 - 27
IEEE Circuits and Systems Magazine - Q3 2020 - 28
IEEE Circuits and Systems Magazine - Q3 2020 - 29
IEEE Circuits and Systems Magazine - Q3 2020 - 30
IEEE Circuits and Systems Magazine - Q3 2020 - 31
IEEE Circuits and Systems Magazine - Q3 2020 - 32
IEEE Circuits and Systems Magazine - Q3 2020 - 33
IEEE Circuits and Systems Magazine - Q3 2020 - 34
IEEE Circuits and Systems Magazine - Q3 2020 - 35
IEEE Circuits and Systems Magazine - Q3 2020 - 36
IEEE Circuits and Systems Magazine - Q3 2020 - 37
IEEE Circuits and Systems Magazine - Q3 2020 - 38
IEEE Circuits and Systems Magazine - Q3 2020 - 39
IEEE Circuits and Systems Magazine - Q3 2020 - 40
IEEE Circuits and Systems Magazine - Q3 2020 - 41
IEEE Circuits and Systems Magazine - Q3 2020 - 42
IEEE Circuits and Systems Magazine - Q3 2020 - 43
IEEE Circuits and Systems Magazine - Q3 2020 - 44
IEEE Circuits and Systems Magazine - Q3 2020 - 45
IEEE Circuits and Systems Magazine - Q3 2020 - 46
IEEE Circuits and Systems Magazine - Q3 2020 - 47
IEEE Circuits and Systems Magazine - Q3 2020 - 48
IEEE Circuits and Systems Magazine - Q3 2020 - 49
IEEE Circuits and Systems Magazine - Q3 2020 - 50
IEEE Circuits and Systems Magazine - Q3 2020 - 51
IEEE Circuits and Systems Magazine - Q3 2020 - 52
IEEE Circuits and Systems Magazine - Q3 2020 - 53
IEEE Circuits and Systems Magazine - Q3 2020 - 54
IEEE Circuits and Systems Magazine - Q3 2020 - 55
IEEE Circuits and Systems Magazine - Q3 2020 - 56
IEEE Circuits and Systems Magazine - Q3 2020 - 57
IEEE Circuits and Systems Magazine - Q3 2020 - 58
IEEE Circuits and Systems Magazine - Q3 2020 - 59
IEEE Circuits and Systems Magazine - Q3 2020 - 60
IEEE Circuits and Systems Magazine - Q3 2020 - 61
IEEE Circuits and Systems Magazine - Q3 2020 - 62
IEEE Circuits and Systems Magazine - Q3 2020 - 63
IEEE Circuits and Systems Magazine - Q3 2020 - 64
IEEE Circuits and Systems Magazine - Q3 2020 - 65
IEEE Circuits and Systems Magazine - Q3 2020 - 66
IEEE Circuits and Systems Magazine - Q3 2020 - 67
IEEE Circuits and Systems Magazine - Q3 2020 - 68
IEEE Circuits and Systems Magazine - Q3 2020 - Cover3
IEEE Circuits and Systems Magazine - Q3 2020 - Cover4
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2023Q3
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2023Q2
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2023Q1
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2022Q4
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2022Q3
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2022Q2
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2022Q1
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2021Q4
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2021q3
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2021q2
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2021q1
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2020q4
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2020q3
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2020q2
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2020q1
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2019q4
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2019q3
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2019q2
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2019q1
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2018q4
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2018q3
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2018q2
https://www.nxtbook.com/nxtbooks/ieee/circuitsandsystems_2018q1
https://www.nxtbookmedia.com