A Highly Power Efficient 2×3 PIN-Diode-Based Intercoupled THz Radiating Array at 425GHz with 18.1dBm EIRP in 90nm SiGe BiCMOS
A Highly Power Efficient 2×3 PIN-Diode-Based Intercoupled THz Radiating Array at 425GHz with 18.1dBm EIRP in 90nm SiGe BiCMOS
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425GHz 下高功率效率、基于 2×3 PIN 二极管的互耦太赫兹辐射阵列，采用 90nm SiGe BiCMOS，具有 18.1dBm EIRP
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发表时间：
2022
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通讯作者：
A. Babakhani
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作者：
Sam Razavian;A. Babakhani
近年来，硅技术中的高效太赫兹产生引起了人们的极大兴趣，因为它为传感、雷达、通信和光谱学提供了集成的低成本解决方案[1]。由于晶体管的 $mathrm{f}_{mathrm{T}}/mathrm{f}_{max}$ 有限，使用基波振荡器直接产生太赫兹是不可行的；因此，基于谐波提取和基频振荡器的倍频已经开发了各种方法[2]。在这些技术中，晶体管的非线性被用来从基波振荡器或倍频器单元产生高次谐波。然而，由于器件的限制，此类系统的效率较低且辐射功率较低。为了补偿低生成功率，优选采用相干阵列方案来增加 EI RP 和辐射功率。调整相位和锁定元件频率以实现相干操作是阵列架构中的重要因素，这可以通过中央本振分布[3]和相互耦合[4]来实现。 LO 分布会导致元件之间的相位不匹配，并通过添加更多块来显着增加直流功耗。通过注入锁定的相互耦合可以保持相位对准。然而，这种类型的耦合具有较低的调谐范围，这使得在宽频率范围内同步元件变得具有挑战性。在这项工作中，提出了一种太赫兹连续波产生技术，其中不依赖晶体管非线性，而是在反向恢复模式下使用 PIN 二极管来产生强谐波。 PIN 二极管与阶跃恢复二极管 (SRD) 类似，受益于急剧的反向恢复，并且在恢复模式下具有高度非线性，可通过上变频毫米波振荡器的输出来实现高效的太赫兹谐波生成，而无需额外的模块和乘法器。基于 PIN 的阵列由 2x3 元件组成，其中差分 Colpitts 振荡器作为核心，推动 PIN 二极管进入反向恢复状态。阵列元件使用集体耦合方法进行相互耦合，该方法可实现元件之间的宽调谐范围和相位匹配。基于 PIN 的阵列在 425GHz 下实现了 0.31 mW 的辐射功率和 18.1dBm EIRP。
Efficient THz generation in silicon technologies has been of great interest over the recent years, as it enables an integrated low-cost solution for sensing, radar, communication, and spectroscopy [1]. Due to the limited $mathrm{f}_{mathrm{T}}/mathrm{f}_{max}$ of transistors, direct THz generation using a fundamental oscillator is not feasible; therefore, various approaches have been developed based on harmonic extraction and the frequency multiplication of a fundamental oscillator [2]. In these techniques, the nonlinearity of transistors is utilized to generate higher harmonics from a fundamental oscillator or frequency-multiplier cells; however, such systems have a poor efficiency and low radiated power due to device limitations. To compensate for the low generated power, a coherent array scheme is preferred to increase EI RP and radiated power. Adjusting the phase and locking the frequency of elements for coherent operation are important factors in array architectures, which can be performed through central LO distribution [3] and mutual coupling [4]. LO distribution can cause phase mismatch between elements and significantly increases the DC power consumption by adding more blocks. Mutual coupling through injection locking can maintain phase alignment. However, this type of coupling has low tuning range, which makes it challenging to synchronize elements over a broad frequency range. In this work, a technique for THz CW generation is presented, in which, instead of relying on transistor nonlinearity, a PIN diode is used in the reverse recovery mode for strong harmonic generation. A PIN diode, similar to a step recovery diode (SRD), benefits from a sharp reverse recovery and is highly nonlinear in the recovery mode, which enables efficient THz harmonic generation by upconverting the output of a mm-wave oscillator without requiring additional blocks and multipliers. The PIN-based array consists of 2x3 elements, where differential Colpitts oscillators are used as the core to push the PIN diodes into reverse recovery. Array elements are intercoupled using a collective coupling approach that enables wide tuning range and phase match between elements. The PIN-based array achieves a radiated power of 0.31 mW and 18.1dBm EIRP at 425GHz.