Introduction
In the context of the global navigation satellite system (GNSS) mobile terminals aiming for miniaturization and low power consumption, this article introduces a high-integration, low-power, multi-band GNSS RFchip. Manufactured using advanced SiGe BiCMOS technology, this chip requires only a 3.3V power supply, with a typical operating current of 35mA, significantly reducing system power consumption. This makes it ideal for applications such as smartphones, portable navigation devices, and more.

Design and Features of the RFchip
To achieve high performance and high integration, the RFchip adopts a single-downconversion receiver architecture. The core of this chip is an on-chip integrated high-performance intermediate frequency (IF) bandpass filter with a center frequency of 46MHz and a bandwidth of 20MHz. Additionally, the chip integrates all key RF functional modules, including low-noise amplifiers, image-suppression mixers, variable-gain amplifiers, frequency synthesizers, and analog-to-digital converters, requiring only a few external components to form a complete RF frontend solution.

In the specific circuit design, the low-noise amplifier uses a CASCODE structure with emitter feedback. This design not only achieves over 15dB of gain but also controls the noise figure to below 2dB, effectively improving the reception sensitivity. The image-suppression mixer combines the Gilbert multiplier structure and broadband matching technology to ensure excellent linearity and image suppression capability. Notably, the intermediate frequency filter uses an active RC structure and integrates an automatic tuning circuit. This allows it to compensate automatically for performance fluctuations caused by process variations and temperature changes, ensuring the stability of the filter’s center frequency and bandwidth.

Performance of the RFchip
Through practical testing, the RFchip demonstrates outstanding overall performance. Its cascaded noise figure is below 3.5dB, with channel gain exceeding 50dB. The in-band flatness is better than 2dB, and the out-of-band suppression is greater than 25dB. Additionally, its automatic gain control (AGC) sensitivity reaches -94dBm, and the phase noise at a 10kHz frequency offset is lower than -85dBc/Hz. All these indicators meet the stringent requirements for the RF frontend of multi-mode GNSS receivers.

Conclusion
In summary, this high-integration, low-power, multi-band GNSS RFchip, with its excellent performance and high degree of integration, provides an ideal core RF solution for the next generation of mobile navigation terminals.