A wideband, low phase variation 6-bit digital step attenuator (DSA) is presented. To further expand the operation bandwidth while keeping low attenuation and phase error, modified π/T-type attenuator structures are introduced. In the large attenuation unit, the modified π-type attenuator structure is adopted, which includes middle adjusting capacitance and bypass compensating capacitance. Moreover, the reduced T-type structure with bypass compensation capacitance is used in the small attenuation units. The influence of the introduced capacitance on various attenuation units is analyzed. To prove the effectiveness of the modified structure on extending the bandwidth, a DSA with a broad bandwidth of DC-25 GHz and low attenuation and phase error is realized in a 0.18 μm SiGe BiCMOS technology. The attenuation range of the attenuator is 31.5 dB with 0.5-dB step, which is controlled by 6 bits digital input. Its root-mean-square (RMS) attenuation error is lower than 0.3 dB, and the phase error (RMS) is below 4.9°. The insertion loss is lower than 11 dB, and the core area is 0.33 mm².

中文翻译：

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基于 0.18 μm SiGe BiCMOS 技术的 DC 至 25 GHz 6 位数字衰减器

提出了一种宽带、低相位变化的 6 位数字步进衰减器 (DSA)。为了在保持低衰减和相位误差的同时进一步扩展工作带宽，引入了改进的 π/T 型衰减器结构。大衰减单元采用改进的π型衰减器结构，包括中间调节电容和旁路补偿电容。此外，小衰减单元采用带旁路补偿电容的缩减T型结构。分析了引入的电容对各种衰减单元的影响。为了证明改进结构在扩展带宽方面的有效性，在0.18 μm SiGe BiCMOS技术中实现了具有DC-25 GHz宽带宽、低衰减和相位误差的DSA。衰减器的衰减范围为 31.5 dB，0. 5-dB 步长，由 6 位数字输入控制。其均方根（RMS）衰减误差低于0.3 dB，相位误差（RMS）低于4.9°。插入损耗低于11dB，纤芯面积0.33mm² .