12-06-2014, 02:54 PM
IC Technology
[attachment=64712]
What advantages do ICs have over discrete components?
Size: Sub-micron vs. millimeter/centimeter.
Speed and Power: Smaller size of IC components yields higher speed and lower power consumption due to smaller parasitic resistances, capacitances and inductances.
Switching between ‘0’ and ‘1’ much faster on chip than between chips.
Lower power consumption => less heat => cheaper power supplies => reduced system cost.
Integrated circuit manufacturing is versatile. Simply change the mask to change the design.
However, designing the layout (changing the masks) is usually the most time consuming task in IC design.
Invention
Early developments of the Integrated Circuit (IC) go back to 1949.
German engineer Werner Jacobi filed a patent for an IC like semiconductor amplifying device showing five transistors on a common substrate in a 2-stage amplifier arrangement.
Jacobi disclosed small cheap of hearing aids.
Transistor Scaling
Until 1980’s technology was mixed, using nMOS, pMOS, bipolar, and some CMOS.
Supply voltage was not scaling, so power was rising.
To reduce power, scale VDD.
Even then power is growing, due to increased die size, and fast frequency scaling
Full Scaling (Constant Electric Field Scaling)
In reality constant field scaling has not been observed strictly. Since the transistor current is proportional to the gate overdrive.
High performance demands have dictated the use of higher supply voltage.
However, higher VDD implies increased power dissipation.
Improved performance is due to the reduced capacitance.
General Scaling
General scaling model dimensions are scaled by a factor S, while voltage are reduced by a factor U.
When voltage is held constant, U=1, the scaling model reduces to the fixed-voltage model.
Offers similar performance scenario identical to the full-and fixed scaling models.
ECL
It is fastest bipolar circuit architecture available today.
It was the technology of choice for large mainframe computers and supercomputers for many many years.
Suffered from relatively high levels of power consumption compared to CMOS technology.
CMOS now offers speed approaching that of emitter-coupled logic and also support much higher circuit density and lower power consumption.
However, high trans conductance of bipolar family leads to develop BiCMOS.
GaAs
It is a III/V semiconductor, and is used in the manufacture of devices such as microwave frequency integrated circuits.
Some electronic properties of gallium arsenide are superior to those of silicon. It has a higher saturated electron velocity and higher electron mobility, allowing gallium arsenide transistors to function at frequencies in excess of 250 GHz.
GaAs logic circuits have much higher power consumption, which has made them unable to compete with silicon logic circuits.
GaAs is not having its native oxide like SiO2 in case of Si.
GaAs in contrast has a very high impurity density, which makes it difficult to build ICs with small structures, suitable up to (500nm)
[attachment=64712]
What advantages do ICs have over discrete components?
Size: Sub-micron vs. millimeter/centimeter.
Speed and Power: Smaller size of IC components yields higher speed and lower power consumption due to smaller parasitic resistances, capacitances and inductances.
Switching between ‘0’ and ‘1’ much faster on chip than between chips.
Lower power consumption => less heat => cheaper power supplies => reduced system cost.
Integrated circuit manufacturing is versatile. Simply change the mask to change the design.
However, designing the layout (changing the masks) is usually the most time consuming task in IC design.
Invention
Early developments of the Integrated Circuit (IC) go back to 1949.
German engineer Werner Jacobi filed a patent for an IC like semiconductor amplifying device showing five transistors on a common substrate in a 2-stage amplifier arrangement.
Jacobi disclosed small cheap of hearing aids.
Transistor Scaling
Until 1980’s technology was mixed, using nMOS, pMOS, bipolar, and some CMOS.
Supply voltage was not scaling, so power was rising.
To reduce power, scale VDD.
Even then power is growing, due to increased die size, and fast frequency scaling
Full Scaling (Constant Electric Field Scaling)
In reality constant field scaling has not been observed strictly. Since the transistor current is proportional to the gate overdrive.
High performance demands have dictated the use of higher supply voltage.
However, higher VDD implies increased power dissipation.
Improved performance is due to the reduced capacitance.
General Scaling
General scaling model dimensions are scaled by a factor S, while voltage are reduced by a factor U.
When voltage is held constant, U=1, the scaling model reduces to the fixed-voltage model.
Offers similar performance scenario identical to the full-and fixed scaling models.
ECL
It is fastest bipolar circuit architecture available today.
It was the technology of choice for large mainframe computers and supercomputers for many many years.
Suffered from relatively high levels of power consumption compared to CMOS technology.
CMOS now offers speed approaching that of emitter-coupled logic and also support much higher circuit density and lower power consumption.
However, high trans conductance of bipolar family leads to develop BiCMOS.
GaAs
It is a III/V semiconductor, and is used in the manufacture of devices such as microwave frequency integrated circuits.
Some electronic properties of gallium arsenide are superior to those of silicon. It has a higher saturated electron velocity and higher electron mobility, allowing gallium arsenide transistors to function at frequencies in excess of 250 GHz.
GaAs logic circuits have much higher power consumption, which has made them unable to compete with silicon logic circuits.
GaAs is not having its native oxide like SiO2 in case of Si.
GaAs in contrast has a very high impurity density, which makes it difficult to build ICs with small structures, suitable up to (500nm)