应用于GNSS接收机的宽频带高线性下变频器研究

A broadband high linearity down-converter for GNSS receiver applications

针对全球导航卫星系统(GNSS)接收机在安全领域的应用要求,提出一种宽频带、高线性和高驱动的新型下变频电路结构.所提出的下变频器由宽频带共栅低噪声跨导放大器、电流型无源混频开关、和增益可调的跨阻驱动放大器组成.该电路采用电容交叉耦合共栅输入跨导增强技术,实现了1.15-1.65 GHz宽频带匹配和全频点GNSS信号的低噪声放大.所提出的新型的桥式跨阻驱动放大器,具有直接驱动50Ω负载阻抗能力,实现了大动态条件下宽增益控制范围和出色的下变频线性性能.流片测试结果表明,提出的下变频器实现了+38 dBm的输出三阶交调截点功率(OIP3),+17 dBm的输出1 dB压缩点功率(OP1dB),10-27 dB可调的转换增益.下变频噪声系数(NF)在1.15-1.65 GHz频段的各种增益下都小于12.6dB.该下变频器在低增益模式下实现了高线性、低噪声和强驱动能力,适合应用于复杂环境下的GNSS接收机.

A broadband high linearity down-converter for the safety-of-life receivers of Global Navigation Satellite System(GNSS)is presented.The proposed novel down-converter with high linearity and high driving ability,consists of a broadband common-gate low-noise transconductance amplifier(CG-LNTA),a current-driven passive mixer and a high linear impedance driving amplifier.To improve the wideband input matching of 1.15-1.65 GHz and all-band GNSS signal reception,a CG-LNTA with gm-boosting technique of capacitor cross-coupled(CCC)is employed.To drive a 50-Ωlowimpedance load and achieve excellent linearity performance,a novel bridge mode transimpedance driving amplifier with variable gain is proposed.Measurement results show that the proposed down-converter achievers+38 dBm output 3rd order intercept point(OIP3),+17 dBm output-referred 1 dB compression point(OP1 dB),10-27 dB variable gain,and less than 12.6 dB noise figure(NF).With high linearity,low noise and sufficient driving capability in low conversion gain mode,the proposed down-converter is suitable for reliable GNSS receiver in complex environments.