MESFET circuits are formed effectively on two layers – the green implant layer and the red gate-metal layer.
182. If the gate-metal layer is in contact with the implant layer _____ is formed.
A. diode
B. transistor
C. switch
D. buffer
Answer: B
If the gate-metal layer is in contact with the implant layer a transistor is formed. The implanted layer and the gate-metal layer interact to form the Schottky gate where they cross one another.
183. When an insulating layer is used in between the implant and gate metal, it is used as?
A. amplifier
B. transistor
C. switch
D. interconnect
Answer: D
If an insulating layer is introduced in between the implant and gate metal, there is no interaction between these layers and it can be used as interconnect.
184. The MESFET properties can be varied by varying the
A. implant
B. implant concentration
C. structure
D. length
Answer: B
The basic properties of MESFET can be modified by varying the implant concentration density.
A MESFET (metal-semiconductor field-effect transistor) is a field-effect transistor semiconductor device similar to a JFET with a Schottky (metal-semiconductor) junction instead of a p–n junction for a gate.
185. Complexity in MESFET design can be reduced by using
A. layout design
B. stick diagram
C. symbolic representation
D. transistor diagram
Answer: C
Through color encoding and symbolic representation of layers, it is possible to remove much of the complexity associated with the design of MESFET.
186. _______ color is used to represent interconnections.
A. red
B. green
C. yellow
D. brown
Answer: A
Schottky is a potential energy barrier for electrons formed at a metal-semiconductor junction. Red (gate-metal) is used to represent the Schottky gate and short interconnections.
187. Which color is used to represent first-level metal?
A. brown
B. blue
C. dark blue
D. green
Answer: B
Blue (metal 1) is used to represent first-level metal and dark blue (metal 2) is used for second-level metal.
188. The _______ mask identifies all active regions.
A. blue layer
B. red layer
C. yellow layer
D. green layer
Answer: D
The green layer mask identifies all active regions such as areas that eventually form E and D type devices, active loads, and implant resistors.
189. ______ forms the more heavily doped channel of D-MESFET.
A. red inside yellow layer
B. green inside yellow layer
C. yellow inside green layer
D. green outside yellow layer
Answer: B
The green region inside the yellow layer mask forms the more heavily doped channel of the D-MESFET.
190. _______ is used to represent the lightly doped channel of E-MESFET.
A. red inside yellow layer
B. green inside yellow layer
C. yellow inside green layer
D. green outside yellow layer
Answer: D
Green regions outside the yellow layer form the lightly doped channel of the E type MESFET.
191. ______ is used to represent implant.
A. yellow
B. red
C. green
D. brown
Answer: C
The green color is used to represent the implant layer. Symbolically it is represented as E-MESFET and it is formed when crossed by gate-metal.
192. _____ is used to represent ohmic contact.
A. yellow
B. red
C. green
D. brown
Answer: D
Brown is used to represent ohmic contact and it is used with source/drain contacts.
193. In the ring diagram, the green line is used to represent
A. E-MESFET
B. D-MESFET
C. Interconnection
D. Transistor
Answer: A
In the ring diagram, a green or dotted line represents E-MESFET while a yellow or solid line represents D-MESFET.
194. E-type and D-type are joined together using
A. metal 1
B. metal 2
C. vias
D. interconnectors
Answer: A
E-type and D-type features are joined together using a blue color which represents metal 1 layer.
195. What is the intermediate stage in converting ring diagram to mask layout?
A. switch logic
B. transistor level diagram
C. symbolic diagram
D. stick diagram
Answer: C
The ring diagrams can be turned into mask layout directly or through an intermediate symbolic representation stage.
196. In symbolic representation, rings are converted into
A. color codes
B. switches
C. sticks
D. circuit elements
Answer: D
Symbolic representation is the intermediate stage when turning a ring diagram to mask layout and here rings are represented as circuit elements.
197. For inverters color code used is
A. red followed by green paths
B. green followed by red paths
C. green followed by yellow paths
D. red followed by yellow paths
Answer: C
The green followed by yellow paths is drawn for inverters and inverter-based logic such as NOR gates.
198. In symbolic representation _________ is used to represent E-MESFET.
A. red transistor
B. green transistor
C. yellow transistor
D. blue transistor
Answer: B
In symbolic representation, the green transistor is used to represent E-MESFET and the yellow transistor is used to represent D-MESFET.
199. Global control paths are run in
A. metal 2
B. metal 1
C. transistor
D. interconnects
Answer: A
Long signal and global control paths are run in metal 2 parallel with the power rails.
200. _______ gives the instruction for the preparation of photomasks.
A. design layout
B. design rules
C. color codes
D. layout map
Answer: B
Design rules are the prescription for the preparation of photomasks that are to be used in the fabrication of integrated circuits.
