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Subelement G6

CIRCUIT COMPONENTS

Section G6B

Analog and digital integrated circuits (ICs); microwave ICs (MMICs); display devices; RF connectors; ferrite cores

What determines the performance of a ferrite core at different frequencies?

  • Its conductivity
  • Its thickness
  • Correct Answer
    The composition, or “mix,” of materials used
  • The ratio of outer diameter to inner diameter

Ferrites are composed of a ceramic mixture. The ratio of ceramic binder, iron powder, and other trace metals can vary, producing different electrical characteristics.

Ferrite core

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What is meant by the term MMIC?

  • Multi-Mode Integrated Circuit
  • Correct Answer
    Monolithic Microwave Integrated Circuit
  • Metal Monolayer Integrated Circuit
  • Mode Modulated Integrated Circuit

MMIC is the abbreviation for Monolithic Microwave Integrated Circuit.

This circuit is used for amplification, mixing, or switching in circuits operating at microwave frequencies (300 MHz to 300 GHz).

Hint: The actual name almost seems one of the least likely, but try to remember that the name refers to microwave frequencies.

Hint 2: MM in Latin is two thousand (2,000), a fairly huge number. "Monolithic" means huge.

Silly Hint: When you see the "MM" in MMIC think of saying "mmm" when you smell your food "Microwaved" (Monolithic Microwave Integrated Circuit).

For more info see Wikipedia: Monolithic Microwave Integrated Circuit (MMIC)

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Which of the following is an advantage of CMOS integrated circuits compared to TTL integrated circuits?

  • Correct Answer
    Low power consumption
  • High power handling capability
  • Better suited for RF amplification
  • Better suited for power supply regulation

CMOS circuits use only a very small amount of current when operating. The largest amount of current is used when the circuit is switching between "On" and "Off".

Hint: I think of it as a “Computer Mini Off Switch”, which uses very little power, like turning off the lights consumes less power.

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What is a typical upper frequency limit for low SWR operation of 50-ohm BNC connectors?

  • 50 MHz
  • 500 MHz
  • Correct Answer
    4 GHz
  • 40 GHz

A 50-ohm BNC connector has a low SWR up to 4GHz, but not up to 40GHz.

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What is an advantage of using a ferrite core toroidal inductor?

  • Large values of inductance may be obtained
  • The magnetic properties of the core may be optimized for a specific range of frequencies
  • Most of the magnetic field is contained in the core
  • Correct Answer
    All these choices are correct

This question could be asking about a couple of things:

(1) What advantage does a toroid core provide as opposed to a straight core?

(2) What advantage does a ferrite core provide as opposed to a powdered iron core?

Based on the correct answer, it seems like it's only asking about toroid versus straight.

Toroids have become popular because the amount of magnetic flux that leaks outside of the core itself is low, which makes it more efficient and it radiates less electromagnetic interference.

Additionally, toroid cores are a closed loop. In a straight core the magnetic field has to go pretty far from one end to enter at the other. This means that the toroid will typically produce a larger inductance.

Finally, by varying the size and thickness and characteristics of the ferrite itself, you can optimize a ferrite toroid for different frequencies.

Silly Hint: the TOROIDAL inductor gives you the TOTAL package.

For more info see Wikipedia: Toroidal inductor

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What kind of device is an integrated circuit operational amplifier?

  • Digital
  • MMIC
  • Programmable Logic
  • Correct Answer
    Analog

An integrated circuit operational amplifier operates as an ANALOG device, because it operates over a CONTINUOUS RANGE of voltage and current.

Hint: Analog devices react/operate in a continuous manner, whereas digital devices react/ in steps or increments.

For more info see Wikipedia: Analogue electronics

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Which of the following describes a type N connector?

  • Correct Answer
    A moisture-resistant RF connector useful to 10 GHz
  • A small bayonet connector used for data circuits
  • A low noise figure VHF connector
  • A nickel plated version of the PL-259

The Type N connector is a moisture-resistant RF connector useful up to 10 GHz.


The Type N is often used for coaxial cable connections, and has a threaded plug similar to a PL-259 but with a moisture-resistant gasket. This type of connector is especially useful for antenna connections not only for its "water-tight" capabilities, but also because it has the same 50-ohm impedance as coaxial cable, and so impedances are matched.

Most manufacturers claim consistent performance up to 11 GHz and many use it up to 18 GHz.

For more info see Wikipedia: Type N connector

Silly hint: “N” for “Nautical”. (Water). Thus, associated with “water-resistant”

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How is an LED biased when emitting light?

  • In the tunnel-effect region
  • At the Zener voltage
  • Reverse biased
  • Correct Answer
    Forward biased

An LED is forward biased when emitting light. In other words, the Light Emitting Diode (LED) lights up when the current flows in the forward direction through the diode PN-junction and photons are given off.

Silly Hint: The Light will lead you Forward!

For more info see Wikipedia: Light-emitting diode

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How does a ferrite bead or core reduce common-mode RF current on the shield of a coaxial cable?

  • Correct Answer
    By creating an impedance in the current’s path
  • It converts common-mode current to differential mode current
  • By creating an out-of-phase current to cancel the common-mode current
  • Ferrites expel magnetic fields

The ferrite bead presents a high impedance to RF signals. As it is located on the outside of the cable, it will present that high impedance to any RF current flowing on the outer shield of the coax. It does not affect the RF current flowing in the inner core of the coax because these currents are contained within the shield braid.

Hint: Ferrite impedes the flow of the RF signal outside the shield. Silly visual: Imagine a ferret with its finger in the dam, holding back the flow.

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What is an SMA connector?

  • A type-S to type-M adaptor
  • Correct Answer
    A small threaded connector suitable for signals up to several GHz
  • A connector designed for serial multiple access signals
  • A type of push-on connector intended for high-voltage applications

An SMA connector is A small threaded connector suitable for signals up to several GHz.


SMA is an acronym for a SubMiniature version A.

To eliminate distractors, note that SMA does not stand for serial multiple access. Also, an SMA is a miniature connector—so not a "large bayonet connector". Lastly, this is not a connector that is specialized for high power or high voltage.

This type of connector is usually used for smaller gauge coaxial cable. It is especially useful for handheld transceiver or other antenna connections because the SMA connector has a 50 ohm impedance, matching that of the coaxial cable, allowing for excellent performance.


Silly Hint: SMA is the the first three letters of the word “small.” There is only one choice of answers with the word “small” in it.

For more info, see Wikipedia: SMA (SubMiniature version A Connector)

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Which of these connector types is commonly used for low frequency or dc signal connections to a transceiver?

  • PL-259
  • BNC
  • Correct Answer
    RCA Phono
  • Type N

The RCA Phono connector is the most commonly used for audio signals in amateur radio stations. Originally manufactured by the RCA company for their audio equipment they are now the standard red, white and yellow plugs used for connecting all types of audio equipment. Sometimes they are referred to as standard composite or component audio/video plugs.

For more info see Wikipedia: RCA connector

Silly hint: “Phono” sounds like phone, which is technology that uses audio.

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