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MMIC PA Design

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • Power amplifiers are used for converting DC input power into significant RF or microwave output power. 

  • To meet size, cost, and reliability requirements, monolithic microwave integrated circuit (MMIC) technology is utilized in power amplifier production. 

  • MMIC power amplifiers exhibit less performance variation compared to discrete component-based power amplifiers.

MMIC PA Design

MMIC PAs are widely used in wireless communication systems

The demand for wireless communication is increasing more than ever. Due to the availability of large bandwidth, mmWaves are extensively employed in wireless communication systems. All wireless communication systems, including mmWave systems, are supported by integrated circuits. With higher frequencies, monolithic microwave integrated circuits (MMICs) are widely used in wireless communication systems. MMIC power amplifiers (PAs) are crucial components in wireless systems. MMIC PA design is challenging and must support multi-wireless system specifications. 

Power Amplifiers

In wireless and radar communication, power amplifiers are some of the most important elements.  Power amplifiers are used for converting DC input power into significant RF or microwave output power. Power amplifiers are incorporated in transmission and receiver modifiers and they permit signal amplification as well.

Usually, wireless communication infrastructure demands high efficiency and high power output from power amplifiers. However, depending on the application platform, the power amplifier design focuses on parameters such as output power, noise figure, gain performance, bandwidth, linearity, efficiency, etc.

Challenges Associated With Power Amplifiers

In modern wireless communication, power amplifiers are inevitable. However, there are several uncertainties and challenges associated with power amplifiers:

  1. In most wireless applications, power amplifiers are the most expensive component in the system.

  2. The overall reliability of the system is influenced by the reliability of the power amplifier.

  3. In systems requiring the linear operation of power amplifiers (analog and digital communication applications), PAs are made to operate at the high bias current or input supply voltage or high output power levels, which compromise the efficiency of the amplifier.

  4. Irrespective of operating at linear or near saturation regions, power amplifiers are the highest power dissipation component in wireless communication systems, thereby demanding superior thermal management systems.

MMIC Power Amplifiers

Similar to electrical performance requirements, power amplifiers have other challenges such as cost, reliability issues, component size, etc. To meet the size, cost, and reliability requirements, monolithic microwave integrated circuit (MMIC) technology is utilized in power amplifier production. MMIC power amplifiers are well known for offering cost-effective high performance, reliability, and compact size.

Advantages of MMIC Power Amplifiers

Power amplifiers can be constructed using either discrete components or as ICs. When MMIC technology is applied to power amplifier design, there are several advantages:

  •  MMIC power amplifiers are small in size and lightweight.
  •  MMIC power amplifiers exhibit less performance variation compared to discrete component-based power amplifiers.
  •  There is no need for post-fabrication lining to set the uniformity level among power amplifiers.
  •  When the associated components are available in a monolithic format, MMIC power amplifiers ensure a higher degree of integration.
  •  It is possible to optimize parameters such as gain, bandwidth, efficiency, etc. in MMIC power amplifiers when multiple gain stages are present.

Drawbacks of MMIC Power Amplifiers

Most disadvantages of MMIC power amplifiers are related to thermal management or temperature rise. Some issues are:

  1. When an MMIC power amplifier dissipates power through the backside of the IC, it increases the complexity and cost of the thermal management system.

  2. If the thermal management fails, the temperature rise in MMICs influences the reliability of operation.

  3. Reducing the size of MMIC power amplifiers to save on costs affects MMIC PA operations.

  4. MMIC power amplifiers limit the circuit tuning possibilities compared to their discrete component counterparts.

MMIC power amplifier designers need to consider both the requirements as well as the significant drawbacks and ensure all system specifications are met by their design.

MMIC PA Design Stages

Depending on the system specifications, each MMIC PA design stage varies. Each MMIC PA design goes through complex analysis and design work before fabrication starts. Cadence’s AWR Design Environment platform offers tools that support the simulation of microwave components such as MMIC PAs. Cadence offers thermal solvers and electromagnetic tools that reduce the iterative design process and time to market for MMIC PAs.

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