Abstract
A four-channel receiver front-end is designed and implemented for interference- and jamming-robust global navigation satellite system (GNSS) in a 0.18-μm CMOS technology. The front-end consists of four identical RF-to-IF signal paths including low-noise amplifiers (LNAs), mixers and IF amplifiers. In addition, it also includes a phase-locked loop (PLL), which synthesizes the local oscillator (LO) signal, and a serial peripheral interface (SPI) for parameter adjustment. To improve the interference and jamming robustness, a novel linearity improvement technology and LO duty cycle adjustment method are applied in LNA and mixer design, respectively. The receiver achieves a gain of 40 dB, an input-referred third-order intercept point (IIP3) of −8 dBm and a jammer-to-signal power ratio (JSR) of 72 dB under 1.8-V and 3.3-V supply, while occupying a 4 × 5 mm2 die area including the electrostatic discharge (ESD) I/O pads.
Highlights
Global navigation satellite system (GNSS) has been utilized to provide the position, velocity and/or time information in many applications such as aircraft navigation systems, automotive applications and portable devices [1,2]
Two methods to control the gain of the front-end are generally utilized in the state-of-the-art works, one of which is to control through serial peripheral interface (SPI) manually [7], which is impractical in a commercial device, and the other is to tune by automatic gain control (AGC) through feedback network automatically [6,8]
GNSS front-end is implemented in a 0.18-μm CMOS technology with the chip area of 4 × 5 mm2
Summary
Global navigation satellite system (GNSS) has been utilized to provide the position, velocity and/or time information in many applications such as aircraft navigation systems, automotive applications and portable devices [1,2]. With the increasing requirement in position accuracy, coverage and reliability, the front-end should be well designed to improve the performance of the GNSS receiver. One promising way to solve this problem is to use multichannel structure It may benefit from nearby interference cancellation and digital beamforming algorithms to further suppress unwanted signals and increase the gain in the direction of the target satellites [4,5]. The gain is usually widely tunable in a traditional GNSS front-end so as to suppress unwanted interference and jamming as well as to achieve an optimal signal amplitude to enhance analog-to-digital converter (ADC) performance [6]. Controlling the gain can maintain the receiver function under strong interference and jamming, the performance is severely sacrificed, causing inaccurate positioning analogous to terrible mobile communication under a harsh environment. In order to obtain precise positioning under such an environment, the design of a GNSS front-end with almost constant gain is proposed in [4] without sacrificing the performance when the Electronics 2020, 9, 291; doi:10.3390/electronics9020291 www.mdpi.com/journal/electronics proposed in [4] without sacrificing the performance when the power of the signal is much lower than the interference or jammer, the the jammer-to-signal ratio (JSR).by
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