Microwave Engineering Questions and Answers for Campus interviews on “Hybrid Microwave integrated Circuits”.
1. In the course of development of microwave circuits, two distinct types of microwave integrated circuits have been developed according to the application requirements.
A. true
B. false
Answer: A
Clarification: There are two distinct types of microwave integrated circuits fabricated. They are hybrid microwave integrated circuits and monolithic microwave integrated circuits. They differ in the method of fabrication in the layers of metallization done.
2. __________ is an important consideration for a hybrid integrated circuit.
A. material selection
B. processing units
C. design complexity
D. active sources
Answer: A
Clarification: Material selection is an important consideration for a hybrid integrated circuit. Characteristics such as electrical conductivity, dielectric constant, loss tangent, thermal transfer and manufacturing compatibility of the material to be used for hybrid microwave circuits are evaluated first.
3. To fabricate a low frequency circuit using the hybrid microwave IC methodology, the material with _______ is preferred.
A. high dielectric constant
B. low dielectric constant
C. high resistivity
D. low resistivity
Answer: A
Clarification: At low frequency applications, a high dielectric constant is desirable because it results in smaller circuit size. At higher frequencies, however the substrate thickness must be decreased to prevent radiation loss and other spurious effects.
4. The mask in a hybrid microwave circuit is made of:
A. rubylith
B. silicon
C. quartz
D. arsenic
Answer: A
Clarification: The mask in hybrid microwave integrated circuits is made of Rubylith, a soft mylar film usually at a magnified scale for high accuracy. Then an actual size mask is made on a thin sheet of glass or quartz.
5. The metalized substrate is coated with __________ covered with the mast and exposed to light source.
A. photoresist
B. GaAs
C. germanium liquid
D. none of the mentioned
Answer: A
Clarification: The metalized substrate is coated with photoresist, covered with the mast and exposed to light source. The substrate can be etched to remove the unwanted areas of the metal.
6. Commonly used software packages for CAD of hybrid microwave integrated circuits are:
A. CADENCE
B. ADS
C. DESIGNER
D. all of the mentioned
Answer: D
Clarification: Before any microwave circuit design is implemented on the hardware, it is economical to simulate the same designs in software and check for the expected theoretical results. A few such software that provide such an environment is CADENCE, ADS, DESIGNER to name a few.
7. In hybrid microwave integrated circuits, the various components of the circuit are etched in the substrate.
A. true
B. false
Answer: B
Clarification: In hybrid integrated circuit design, after all initial design steps are completed, the discrete components are soldered or wire bonded to the conductors This can be done manually or through automated computer-controlled pick and place machines.
8. Once the circuit components are designed and fabricated for certain specific values, they cannot be changed as per the requirement later.
A. true
B. false
Answer: B
Clarification: IN HIC, provision is made for variations in component values and other circuit tolerances by providing tuning or trimming stubs that can be manually trimmed for each circuit. This increase circuit yield but also increases the cost of manufacture.
9.________ is a micromachining technique where suspended structures are formed on silicon substrates.
A. MMIC
B. HIC
C. RF MEMS
D. none of the mentioned
Answer: C
Clarification: RF MEMS switch technology is a micro machining technique where suspended structures are formed in silicon substrates. These can be used in microwave resonators, antennas and switches.
10. Depending on the single path (capacitive or direct contact) and the attenuation mechanism MEMS switch can be used for various configurations for various devices.
A. true
B. false
Answer: A
Clarification: A MEMS switch can be used in several different configurations depending on the single path, actuation mechanism, pull-back mechanism and the type of structure. One such example is switching the capacitance of a single path between high and low values by moving a flexible conductive membrane through the application of DC controlled voltage.
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