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


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 DIP’s 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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Tags: Radio, Everything Else, MMIC, IC packaging, MMICs

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