线性限幅器的设计与研究

Design and Research of Linear Limiters

ADC芯片广泛用于现代无线电系统,已成为大量军事装备中不可或缺的部分。复杂电磁环境可导致接收机灵敏度下降甚至失效。接收机用的ADC芯片耐受大信号能力有限,急需一种既能保证其正常工作,又不会影响其采样灵敏度的器件,为此开发了一种新的器件,线性限幅器。为满足高线性度的限幅要求,介绍了一种基于PIN二极管的小型化线性限幅器设计方案。用ADS仿真设计,薄膜混合工艺、一体化陶瓷管壳装配实现,开发出了一系列频率覆盖10 MHz^5 GHz,尺寸仅5 mm×5 mm×2.5 mm的高线性度限幅器。测试结果表明,P波段300~500 MHz产品损耗小于0.6 dB,输出P-1大于11 dBm,输入0 dBm信号时OIP3大于35 dBm,输入25 dBm信号时漏功率低于12 dBm,最大可承受功率5 W。ADC芯片的可靠性大大提高,具有广阔应用前景。

Analog to digital converter(ADC)has been widely used in modern RF systems,becoming an indispensable part for military equipment.Nowadays complicated electromagnetic environment may lower the sensitivity of receiver or even destroy it.The ADC chip used in the receiver has limited ability to receive large signals,so a device that can ensure its normal operation without affecting its sampling sensitivity is urgently needed.In this paper,a new device,a miniaturization linear limiter based on PIN diodes is invented to meet the demand of high linearity.By means of ADS,a series of linear limiters have been developed,covering from 10 MHz to 5 GHz.The linear limiters are fabricated by using thin film hybrid integrated circuit technology,in a 5 mm×5 mm×2.5 mm integrated ceramic package.A P-band(300-500 MHz)linear limiter is measured.The result shows that the insertion loss is less than 0.6 dB and the output P-1 is greater than 11 dBm.The output IP3 is greater than 30 dBm with two 0 dBm input signals.Capable of handling up to 5 W incident power levels,the limiter allows less than 12 dBm leakage power to pass through it at 25 dBm incident power level.The linear limiters can greatly improve the reliability of ADC and have broad application prospect.