RF chips serve as the core component in modern wireless communication and navigation systems, directly determining the sensitivity, anti-jamming capability, and integration level of the entire system. With the comprehensive networking of China’s BeiDou Navigation System and the rapid development of 5G millimeter-wave communication, the demand for high-performance and highly autonomous RF chips is increasing. This article explores the implementation path and technical challenges of RF chips in system architecture, key circuit design, and integration optimization, focusing on typical applications in navigation and millimeter-wave systems.

1. Application and Autonomous Design of RF Chips in Navigation Systems

In both civil and military navigation systems, multi-mode compatibility (such as BeiDou, GPS, GLONASS, Galileo) has become a development trend. Traditional navigation receivers have largely relied on foreign chips, leading to supply chain and technical security risks. To address this, domestic research institutions have developed a highly integrated, fully autonomous navigation RF chip (RFIC) using RF-CMOS technology, integrating modules such as low noise amplifiers (LNA), mixers, complex filters, variable gain amplifiers (VGA), and ADCs, creating a complete signal processing chain from RF to digital intermediate frequency.

This RF chip adopts a one-stage down-conversion low-intermediate frequency architecture, effectively reducing the complexity of peripheral circuits while ensuring system performance. The LNA, as the first stage of the receiver chain, is crucial in determining the noise figure and impedance matching. The design uses a source degeneration inductor structure combined with a capacitive-inductive matching network to achieve 50Ω input matching while optimizing the noise figure to below 2 dB. The overall system noise figure is below 4 dB, significantly enhancing receiver sensitivity.

Additionally, the intermediate frequency filter uses a fifth-order Chebyshev Gm-C complex filter structure, which adjusts gain, center frequency, and bandwidth through transconductance and capacitance. This structure achieves an image rejection ratio (IMRR) better than 40 dB with a 4 MHz bandwidth and a passband flatness of 0.55 dB, improving the system’s anti-jamming and signal selection capabilities.

2. Integration and Challenges of RF Chips in W-Band T/R Components

In millimeter-wave frequencies, especially in the W-band (75–110 GHz), the design of RF chips faces challenges such as higher frequencies, smaller wavelengths, and greater transmission losses. For example, in a 77 GHz collision avoidance radar, the T/R components need to exhibit high gain, low noise, fast switching, and high integration. In recent years, the introduction of domestically developed 2-transmitter 4-receiver SOC RF chips has provided a feasible path for miniaturization and cost reduction of millimeter-wave radar frontends.

These RF chips integrate modules such as power amplifiers, low-noise amplifiers, mixers, phase shifters, and frequency synthesizers, supporting multi-channel simultaneous operation. To ensure the integrity of high-frequency signals, the chips are coupled with high-performance RF interconnection structures, such as waveguide-microstrip probes, vertical transitions, and BGA-to-microstrip-line conversions. By optimizing probe structures and integrating short-circuit surfaces, these designs achieve broadband performance with insertion loss of <0.2 dB and return loss better than –20 dB in the 72–82 GHz frequency range, significantly enhancing system efficiency.

3. Common Key Technologies in RF Chip Design

Whether for navigation chips or millimeter-wave RF chips, design efforts generally focus on the following core aspects:

Low Noise and High Linearity
The LNA, as the first amplifier stage, determines the system’s sensitivity, while the linearity of the final-stage VGA and power amplifier (e.g., OIP3) affects the system’s dynamic range and anti-jamming ability. Through cascaded gain optimization and negative feedback structures, a balance between noise and linearity can be achieved.

Filters and Image Rejection
Complex filters are crucial in low-intermediate frequency architectures, with their out-of-band rejection and passband flatness directly affecting signal quality. The Chebyshev structure, with its steep transition band, is widely adopted and further enhanced with pre-calibration modules to improve IMRR.

System Integration and Electromagnetic Compatibility
Highly integrated RF chips combine analog and digital circuits, and digital switching noise can affect RF performance through substrate coupling. Techniques such as protective rings, independent power domains, and deep N-well isolation on layouts can effectively suppress noise coupling and improve system stability.

Configurability and Application Adaptability
Modern RF chips generally support SPI or I²C interfaces, allowing users to dynamically adjust gain, bandwidth, and operational modes to adapt to the varying needs of multi-mode navigation or radar systems.

4. Conclusion and Outlook

RF chips act as the “senses” and “voice” of wireless systems, with their performance directly impacting the overall level of communication, navigation, radar, and other devices. Currently, domestic RF chips in the navigation and millimeter-wave fields have made significant progress, achieving full-link autonomy from architecture design and circuit optimization to system integration. In the future, as process nodes shrink further, packaging technologies like SiP and 3D-IC evolve, and AI-assisted design tools are applied, RF chips will continue to break through in higher frequencies, lower power consumption, and stronger intelligence, providing solid support for China’s independent and controllable communication and perception systems.