Author Affiliations
Abstract
1 Nanjing Research Institute of Electronics Technology, Nanjing 210039, China
2 Key Laboratory of IntelliSense Technology, China Electronics Technology Group Corporation, Nanjing 210039, China
Transient response of an erbium-doped fiber amplifier (EDFA) is studied in an externally-modulated analog link. Double tones represented as transmitted radio frequency and dither signals are introduced. Extra modulation is generated owing to the EDFA’s transient response caused by a low-frequency dither signal. Therefore, the parasitic modulation is superposed to the output signals and may significantly affect in-band electrical spectra. Analytical and numerical solutions are both given, which agree well with experimental results. This work indicates that a suitable dither signal should be selected to maximize the carrier to intermodulation ratio. In-band spurious free dynamic range is optimized in the meantime.
erbium-doped fiber amplifier transient response dither signal carrier to intermodulation ratio externally-modulated analog link Chinese Optics Letters
2022, 20(1): 013901
1 解放军信息工程大学 信息系统工程学院, 郑州 450001
2 解放军 68002部队， 兰州 730000
采用幂级数法分析得到了线性化器与行波管放大器相反的非线性特性，并建立了预失真放大器的幂级数模型。根据反并联二极管对电路能够产生奇次谐波的特点，利用反并联肖特基二极管对、正交混合电桥、二极管电路的匹配网络等结构，通过对各结构的分析优化，设计了用于Ka波段行波管的预失真线性化器。实验结果表明：该线性化器在29~31 GHz频段范围内能为行波管放大器的载波交调比带来最大19 dB的改善。
预失真线性化器 非线性特性 载波交调比 肖特基二极管 predistortion linearizer nonlinear characteristics carrier-to-intermodulation ratio Schottky diodes
分析了光栅色散抖动对有线电视信号的影响,估计出落在信号50MHz～550MHz范围内互调产物功率约占所有互调产物功率的10%～50%。为了抑制色散抖动幅度,光栅的折射率变化应该从初值零渐渐升到最大值。长度为10cm、包络为升余弦与tanh(4z)的光栅都能满足有线电视系统的要求。此外还发现,长光栅对应的抖动周期小,因此对信号的影响也小;具有升余弦包络的光栅比tanh(4z)光栅更能有效地抑制色散抖动。
光纤光栅 色散补偿 时延抖动 有线电视 载波互调比
