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2020 Extra Class study guide - E6E Analog ICs: MMICs, IC packaging
characteristics

Posted: 14 Feb 2020 07:14 AM PST
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Monolithic microwave integrated circuits, or MMICs, are ICs that are made
to perform various functions at high frequencies. MMICs have:

Controlled gain.
Low noise figure (VHF and UHF preamplifiers have a noise figure typically 2
dB or less).
Constant input and output impedance (50 Ω, of course, for RF circuits) over
the specified frequency range.


These features make them a popular choice for high-frequency circuits, from
VHF through microwave.
QUESTION: What characteristics of the MMIC make it a popular choice for VHF
through microwave circuits? (E6E06)

ANSWER: Controlled gain, low noise figure, and constant input and output
impedance over the specified frequency range
QUESTION: Which of the following noise figure values is typical of a
low-noise UHF preamplifier? (E6E05)

ANSWER: 2 dB
QUESTION: Which is the most common input and output impedance of circuits
that use MMICs? (E6E04)

ANSWER: 50 ohms

MMICs are often made from the semiconductor gallium nitride because it is
the material most likely to provide the highest frequency of operation.
Another semiconductor that is used for devices operating at UHF and higher
frequencies is gallium arsenide (GaAs). One reason for this is that it has
higher electron mobility than silicon.
QUESTION: Which of the following materials is likely to provide the highest
frequency of operation when used in MMICs? (E6E03)

ANSWER: Gallium nitride

QUESTION: Why is gallium arsenide (GaAs) useful for semiconductor devices
operating at UHF and higher frequencies? (E6E01)

ANSWER: Higher electron mobility

To achieve these specifications, great care is taken in building and using
circuits that use MMICs. For example, MMIC-based microwave amplifiers use
microstrip construction to connect to the integrated circuit. To prevent RF
from getting into the power supply, power is connected to an MMIC through a
resistor and/or RF choke connected to the amplifier output lead.
QUESTION: What type of transmission line is used for connections to MMICs?
(E6E07)

ANSWER: Microstrip

QUESTION: How is power supplied to the most common type of MMIC? (E6E08)

ANSWER: Through a resistor and/or RF choke connected to the amplifier
output lead
Device packages

Integrated circuits come in many different types of packages. One of the
most common packages for an integrated circuit is the dual-inline package,
or DIP. DIPs have two rows of connecting pins placed on opposite sides of
the package. Because a DIPs pins are made to fit into the holes on a
printed-circuit board and extend through that board, it is called a
“through-hole� type.
QUESTION: What is a characteristic of DIP packaging used for integrated
circuits? (E6E11)

ANSWER: A total of two rows of connecting pins placed on opposite sides of
the package (Dual In-line Package)

QUESTION: Which of the following device packages is a through-hole type?
(E6E02)

ANSWER: DIP

For a variety of reasons, electronics companies are moving away from ICs in
through-hole, dual inline packages and moving towards surface-mount
packages. One reason for this is excessive lead length. ICs in surface
mount packages are leadless and soldered directly to circuit boards. They
offer a number of advantages, including:

Smaller package sizes, which means printed circuit boards are smaller.
Shorter circuit board traces.
Less parasitic inductance and capacitance, which makes their performance at
high frequencies more predictable.

QUESTION: Why are DIP through-hole package ICs not typically used at UHF
and higher frequencies? (E6E12)

ANSWER: Excessive lead length
QUESTION: Which of the following component package types would be most
suitable for use at frequencies above the HF range? (E6E09)

ANSWER: Surface mount
QUESTION: What advantage does surface-mount technology offer at RF compared
to using through-hole components? (E6E10)

ANSWER: All these choices are correct



Smaller circuit area
Shorter circuit-board traces
Components have less parasitic inductance and capacitance




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characteristics appeared first on KB6NUs Ham Radio Blog.