Advanced RF MEMS
Answers to RF Cafe Quiz #36

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RF Cafe Featured Book - Advanced RF MEMS, by Stepan LucyszynThis quiz is based on the information presented in Advanced RF MEMS, by Stepan Lucyszyn. This book is full of cool micrographs of actual device geometries. Cambridge University Press is the publisher. Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway.

1.  What does the acronym MEMS stand for?

b)  Microelectromechanical Systems
     (see Preface)

2.  Which material is commonly used in RF MEMS for its superior magnetic and thermal
     expansion properties?

c)  Electroplated nickel
     In recent years, electroplated nickel has been used as a structural material in microfabricated
     circuits, RF MEMS switches and antennas. Its thermal expansion coefficient is 5x that of
     polycrystalline silicon.  (see page 6)

3.  What distinguishes MEMS devices from traditional integrated circuits?

d)  Physical displacement of internal components
     Moveable, three-dimensional physical structures are created to perform mechanical functions.

4.  Which properties of a MEMS RF switch are
     superior to a solid state RF switch?

a)  Insertion loss and bandwidth
     In some aspects, such as power consumption,
     isolation, insertion loss and bandwidth,
     RF MEMS switches have and advantage over
     electronic PIN diode and FET devices.
     (see page 37)

5.  Which properties of a MEMS RF switch are
     inferior to a solid state RF switch?

b)  Speed and size
     The response time of RF MEMS switches is
     much longer than that of electronic switches.
     (see page 37)

6.  What is the purpose of a sacrificial layer during MEMS fabrication?

d)  Allows dry etching to reduce undercutting and erosion common with wet etching
     Dry etching of  with an oxygen plasma allows high selectivity when removing materials.
     (see page 63)

7.  Which application would be perfect for multi-pole, multi-throw MEMS RF switch?

d)  All the above.
     Duh.  (see page 90)

8.  What is the purpose of a "hold electrode?"

a)  To counter induced bias from a strong RF signal power level
     As a way of avoiding self-actuation, through an excess in the mean RF signal power level,
     a number of switches designs have incorporated a second hold electrode, in addition to
     the normal pull-down electrode.  (see page 95)

9.  Which phenomenon is possible in a MEMS device but not in a solid state device?

a)  Vibration-induced actuation
     Self-actuation can occur due to vibration or shock.  (see page 129)

10.  What is zero-level (0-level) packaging?

c)  On-wafer encapsulation
     Zero-level packaging creates an on-wafer, device-scale, enclosure (or sealed cavity for) the
     MEMS, serving as the first protective interface.  (see page 233)