**2.2 MMIC- monolithic microwave integrated circuits**

MMIC are circuits in which passive and active elements are generated on the same dielectric substrate, as presented in **Figure 2**, by using a deposition scheme as epitaxy, ion implantation, sputtering, evaporation, and diffusion. The layout of the MMIC chip in **Figure 2** consists passive and active elements such as resistors, capacitors, inductors and FET, Field Effect Transistor.

### *2.2.1 MMIC design features*

MMIC components cannot be tuned. Accurate design is crucial in the design of MMIC circuits. Accurate design may be achieved by using 3D electromagnetic software such as ADS and HFSS.

Materials used in the production of MMIC chips are SiGe, Silicon, GaAs, GaN, and InP. MMIC design is sensitive to large statistic scattering of the components, electrical parameters. Production of MMIC wafers in FAB are expensive, around \$200,000 per run. Designer goal is to meet with customer specifications in the first design iteration. Compact MMIC components.

yields lower cost of the MMIC chips. **Figure 3** presents MMIC design process.

**5**

*2.2.2 MMIC technologies processes*

to 18GHz.

*MMIC design process.*

**Figure 3.**

**Figure 2.**

GaAs WAFER.

• 0.25micron GaAs PHEMT amplifiers for power applications at 12GHz

• 0.15micron GaAs PHEMT for applications at 18GHz to 40GHz.

• GaAs PIN process for switching applications with low power loss.

• HBT, SiGe, InP, GaN, RFMEMS, RFCMOS are new Ka band process

Wafer size may be "3, 5" or 6″. **Figure 4** presents a chip layout located on

*Introductory Chapter: Ultra-Wideband Technologies DOI: http://dx.doi.org/10.5772/intechopen.97675*

*Layout of MMIC chip with passive and active components.*

*Introductory Chapter: Ultra-Wideband Technologies DOI: http://dx.doi.org/10.5772/intechopen.97675*

## **Figure 2.**

*Layout of MMIC chip with passive and active components.*

#### **Figure 3.** *MMIC design process.*

#### *2.2.2 MMIC technologies processes*


Wafer size may be "3, 5" or 6″. **Figure 4** presents a chip layout located on GaAs WAFER.

**Figure 4.** *GaAs WAFER layout and assembly.*

	- Amplifiers LNA, Power amplifiers, wideband power amplifiers, Distributed TWA
	- Mixers balanced, Star, sub-harmonic
	- Switches PIN, PHEMT, T/R matrix
	- Frequency multipliers active, passive
	- FET- Field Effect Transistor
	- HEMT- High Electron mobility transistor
	- PHEMT- pseudo-morphic HEMT
	- MHEMT- metamorphic HEMT
	- D-HBT Double hetero-structure bipolar transistor
	- CMOS- Complementary metal-oxide semi-conductor
	- BJT- Bipolar Junction transistor
	- Modulators QPSK, QAM (PIN, PHEMT)
	- Multifunction RX chip, TX chip, Switched Amp chip, LO chain

**Table 1** presents types of devices fabricated by using MMIC Technology.


**7**

*2.3.1 Semiconductor in MMIC devices*

Si CMOS MMIC modules are low power and low-cost devices. Si CMOS MMIC modules may operate in frequencies lower than 0.2THz. SiGe MMIC devices are used as medium power high gain devices. SiGe MMIC modules may operate in frequencies lower than 0.2THz. InP HBTs modules may operate in frequencies lower

*Introductory Chapter: Ultra-Wideband Technologies DOI: http://dx.doi.org/10.5772/intechopen.97675*

**2.3 Advantages of GaAs versus silicon in MMIC design**

are compact and have low volume and area (from around 1 mm<sup>2</sup>

Traditionally low frequency MMICs are produced on silicon substrate. Production costs of MMICs on silicon substrate are cheaper. High frequency MMICs are produced on gallium arsenide (GaAs), a III-V compound semiconductor. MMICs

MMICs can be produced in low-cost mass production. The electronic properties of GaAs are significantly better than those of silicon. GaAs has a higher electron mobility and higher saturated electron velocity than silicon. These properties allow transistors produced on GaAs to operate at frequencies higher than 0.3THz. In comparison to silicon devices, GaAs chips are less sensitive to heat because their higher bandgap. Noise of GaAs modules at high frequencies is lower considerably than the noise of silicon modules because of lower resistive device parasitic and higher carrier mobility. These features make GaAs chips and modules attractive to smartphones, cellular phones, medical communication systems, radars, and high frequency phased arrays. Gunn diodes are produced on GaAs substrate to generate RF signals. GaAs devices can be used to emit light efficiently since they have a direct band gap. Silicon devices are very poor at emitting light due to their indirect bandgap. Recent advances may make silicon lasers and LEDs possible. Si LEDs cannot emit visible light and rather work in IR range due to theirs lower bandgap. However, GaAs LEDs may function in visible red light. GaAs substrate is a good choice in high power applications for space electronics devices and optical applications. Silicon is a cheaper substrate than GaAs substrate. Silicon crystal has a significantly mechanically stable structure. Silicon can be grown to very large diameter units. Silicon modules have very high yields. Silicon modules are very attractive for design and production of very large ICs due to good thermal properties of silicon which enable very dense packing of transistors. Silicon dioxide is one of the best insulators, this is a major advantage of Silicon. Silicon dioxide can easily be used in silicon devices. Silicon dioxide layers are adherent to the underlying Silicon layer. GaAs does not have does not have stable oxide does not form a stable adherent insulating layer. An important advantage of silicon over GaAs is the higher hole mobility of silicon which allows the production of higher-speed P-channel field effect transistors. These transistors are required for CMOS logic. GaAs transistors lack a fast CMOS structure. So, GaAs logic circuits have much higher power consumption, GaAs logic cannot compete with silicon logic modules. Silicon technology has lower production cost compared with GaAs devices, contributing to a cheaper Silicon IC. Silicon wafer diameters are typically, 20 cm or 28 cm. GaAs wafer diameters are 10 cm to 15 cm. Other, Indium Phosphide (InP) III-V technologies, offers better properties than GaAs in terms of higher cutoff frequency, gain, and noise figure. InP devices are more expensive than silicon and GaAs modules. InP wafer sizes are smaller than GaAs wafers and are more fragile. Silicon Germanium technology offers higher speed transistors than conventional Silicon devices with similar cost expenses. Gallium Nitride, GaN, is used to produce power amplifiers MMICs. GaN transistors can work at much higher voltages and function at much higher temperatures than GaAs transistors, they are used to produce power amplifiers at high frequencies. Properties of dielectric substrates used in MMIC technology are given in **Table 2**.

to 10 mm2

).

**Table 1.** *Materials used in MMIC technology.*
