Monolithic MICs and Microwave Resonators

Microwave Integrated Circuits (MICs) built on a single substrate with all components integrated together.

A capacitor formed by two parallel conductive plates separated by a dielectric layer.

A circuit element that stores energy at a specific microwave frequency.

A resonator with an open end, often used in MICs due to easier control.

A resonator design to reduce radiation from the open end, increasing Q-factor.

A circular resonator that minimizes fringe effects, ideal for specific applications.

A circular resonator with a large radius, capable of higher oscillation modes.

A resonator constructed using a dielectric material with specific properties (ε, tanδ, temperature coefficient).

Dielectric materials with high dielectric constants (around 40 to 70) are used for 3D resonators, concentrating most of the electromagnetic energy within the resonator.

Lumped inductors in planar transmission lines can be made in different configurations (straight strip, meander line, spiral).

Simple inductors have inductance values from 0.5 to 3.0 nH. Straight strips are used for lower inductance values, while meander lines are used to reduce the area occupied by the element.

Spiral inductors can be circular, rectangular, or octagonal. They are connected to the outside using vias, air bridges, or bond wires.

The resistance of a spiral inductor depends on the frequency due to the skin effect.

The Q-factor of an inductor depends directly on inductance and geometric parameters like width-to-spacing ratio and outside diameter.

Spiral inductors have parasitic capacitance between turns, and additional capacitance when a ground plane is present.

The self-resonant frequency of an inductor is the frequency at which the inductor behaves like a capacitor. It should be at least twice the maximum operating frequency for the inductor to have a constant value.

The presence of a ground plane near a spiral inductor decreases its inductance value. This decrease is more significant as the ground plane is brought closer.

For optimal performance, a spiral inductor should have a wide line width and a small overall diameter. This means minimizing the space between turns while maintaining a compact structure.

Real-world fabrication limits the minimum line width (W) and space between turns (S) in monolithic circuits (on-chip) and hybrid MICs (multi-layer).

An inner diameter to outer diameter ratio of 0.5 in a spiral inductor optimizes the quality factor (Q). This means it minimizes losses in the inductor.

These are two main fabrication techniques used in hybrid microwave integrated circuits (HMICs) to create passive elements like resistors, capacitors, and conductors. They differ primarily in the thickness of the deposited material layers.

Thick-film technology involves printing, baking, and trimming processes. Special pastes are used to create conductive paths, resistors, and capacitors on a substrate. The paste is then baked and trimmed to achieve precise values.

Thick-film technology uses various materials like silver, gold, and palladium-gold for conductors, resistive pastes for resistors, and dielectric pastes for capacitors.

Thick-film technology is suitable for low-cost manufacturing and finds applications in HMICs up to 20 GHz. It allows combining RF and digital functionalities on a single substrate.

A process for creating thin, precise electronic circuits. It involves layering different metals (like chromium, nickel, and gold) on a smooth substrate, using sputtering and photolithography techniques to create patterns. Finally, a high-conductivity metal is electroplated to achieve the desired thickness.

A deposition process that uses a plasma to bombard a target material, causing tiny particles of the target to be ejected and deposited onto a substrate. This process is commonly used in thin-film technology to create thin layers of metals.

A process used to create precise patterns on a thin film. It involves exposing a photosensitive material to ultraviolet light through a mask. This process is crucial for forming the circuit patterns in thin-film technology.

The depth to which a microwave signal can penetrate a conductive material. It depends on the frequency of the signal and the conductivity of the material.

A type of resonator used in microwave circuits that is formed by a short-circuited transmission line. It is more difficult to control and has a higher Q-factor than an open-circuited resonator.

A measure of the ability of a resonator to store energy. A higher Q-factor means a resonator can store energy for a longer time and produce a sharper resonance peak.

The base material on which thin films are deposited. It provides the foundation for the circuitry and can be made from materials like alumina, aluminum nitride, or quartz.

Discontinuities in microwave integrated circuits (MICs) are variations in the physical structure of the transmission line, like open ends, short circuits, gaps, bends, and junctions. They affect the behavior of signals, affecting parameters like impedance and signal reflection.

An open-ended transmission line in a MIC acts like a capacitor, with electric fields radiating outward. This can affect the effective length and capacitance of the line.

A short circuit in a MIC acts as a grounded point, impacting the current and electric fields. It forces a specific voltage at the short circuit, affecting the signal flow.

A gap in the transmission line acts as a capacitor, affecting the impedance and causing signal reflection. It plays a crucial role in building filters or providing isolation.

An air bridge is a technique used to reduce parasitic capacitance by introducing an air gap in the transmission line. It improves signal quality and reduces losses in high-frequency circuits.

Bends or corners change the direction of the transmission line, affecting impedance and signal reflection. They are essential components in building resonant structures, filters, and directional couplers.

A step refers to a change in width of the transmission line, creating a junction between two sections with different impedances. It is used in transformers, filters, and matching networks to change the flow of signals.

A T-junction combines or splits signals at different angles. It is crucial for building components like splitters, combiners, directional couplers, and bias networks.