What Are Microwave Integrated Circuits?

Microwave integrated circuits are circuits that work in the microwave and millimeter-wave bands, with microwave passive components, active devices, transmission lines, and interconnects integrated on a single substrate.

Microwave integrated circuits are circuits that work in the microwave and millimeter-wave bands, with microwave passive components, active devices, transmission lines, and interconnects integrated on a single substrate.

Chinese name

Microwave integrated circuit

Foreign name

microwave integrated circuit, MIC

Introduction to microwave integrated circuits

Can be divided into hybrid microwave integrated circuits and monolithic microwave integrated circuits. A hybrid microwave integrated circuit is a functional block that uses a thin film or thick film technology to make a passive microwave circuit on a substrate suitable for transmitting microwave signals. The circuit is designed and manufactured according to the needs of the system. Commonly used hybrid microwave integrated circuits include microstrip mixers, microwave low-noise amplifiers, power amplifiers, frequency multipliers, phased array units, and other broadband microwave circuits. The monolithic microwave integrated circuit is a functional block in which components, transmission lines, and interconnection lines are directly fabricated on a semiconductor substrate using a planar technology. Gallium arsenide is the most commonly used substrate material. Microwave integrated circuits started in the 1950s. An important reason why microwave circuit technology is shifting from coaxial lines, waveguide components, and systems composed of them to planar circuits is the development of microwave solid-state devices. In the 1960s and 1970s, alumina substrates and thick-film thin-film processes were used; in the 1980s, there were monolithic integrated circuits.

Classification of microwave integrated circuits

Microwave integrated circuit

Using thick-film technology or thin-film technology, various microwave functional circuits are fabricated on a medium suitable for transmitting microwave signals, and then discrete active components are installed at corresponding positions to form a microwave integrated circuit. Microwave integrated circuits use high-alumina porcelain, sapphire, quartz, high-value ceramics, and organic media. There are two types of circuit: distributed parametric microstrip circuit and lumped parameter circuit. Active devices use packaged microwave devices or chips. The main characteristics of microwave integrated circuits are designed and manufactured according to the requirements of the microwave machine and the division of the microwave band. Most of the integrated circuits used are dedicated. Commonly used are microstrip mixers, microwave low-noise amplifiers, microwave integrated power amplifiers, microwave integrated oscillators, integrated frequency doublers, microstrip switches, integrated phased array units, and various broadband circuits.

Monolithic microwave integrated circuit

An integrated circuit in which a microwave functional circuit is fabricated on a chip of a gallium arsenide material or other semiconductor material by a semiconductor process. Microwave circuits made of silicon materials operate in the 300-3000 GHz band, which can be considered as an extension of silicon linear integrated circuits, and are not included in the monolithic microwave integrated circuits.

The manufacturing process of GaAs monolithic microwave integrated circuit is to form an active layer by epitaxial growth or ion implantation on a semi-insulating GaAs single wafer; implanting oxygen or protons to produce an isolation layer (or other ions suitable for generating an isolation layer) ); Inject beryllium or zinc to form a PN junction; make metal-semiconductor barriers by electron beam evaporation; use submicron lithography, dry etching, passivation protection and other processes to make active devices (such as diodes, field effect transistors) and Passive components (inductors, capacitors, resistors and microstrip component couplers, filters, loads, etc.) and circuit patterns. Circuit design is also divided into two forms of lumped parameters and distributed parameters. Distribution parameters are mainly used in power circuits and millimeter-wave integrated circuits. Millimeter-wave integrated circuits refer to integrated circuits that operate in the range of 30 to 300 GHz.

Gallium arsenide is more suitable than silicon for making monolithic microwave integrated circuits (including ultra-high-speed circuits) mainly due to: the resistivity of semi-insulated gallium arsenide substrates is as high as 107-109 ohm · cm, and the microwave transmission loss is small; GaAs has an electron mobility about 5 times higher than that of silicon, and has a high operating frequency and fast speed. The key active device is a gallium arsenide metal-semiconductor field effect transistor, which is a multifunctional device with good radiation resistance, so gallium arsenide Monolithic microwave integrated circuits have broad application prospects in solid-state phased array radar, electronic countermeasure equipment, tactical missiles, television satellite reception, microwave communications and ultra-high-speed computers, and large-capacity information processing.

Monolithic microwave integrated circuits that have been successfully developed and become practical include monolithic microwave integrated low noise amplifiers, monolithic TV satellite receiver front-ends, monolithic microwave power amplifiers, and monolithic microwave voltage-controlled oscillators. The design of this circuit is mainly based on the functions of generating, amplifying, controlling and information processing of microwave signals. Most of the circuits are designed according to the requirements of different complete machines and the characteristics of the microwave frequency band, and have strong specificity.

Comparison of microwave integrated circuits

Compared with hybrid integration, monolithic integration has the following characteristics:

1) With a higher use limit frequency, the bandwidth can be made wider.

2) Since the connection points on the circuit are reduced, the performance consistency is better.

3) The substrate area is smaller, the integration degree can be higher, and the volume and weight are smaller.

4) Do not use adjustable components.

5) The avalanche transit time diode (IMPATT) in collision avalanche transit time mode cannot be used in monolithic integration.

6) Computer-aided design must be used for accurate circuit design.

7) Monolithic integration can only be small in cost and low in price in large quantities.