This paper presents general SPICE photonic models for closed-loop electronic-photonic co-simulation. SPICE models are originally intended for electronic devices, which have significantly different physics compared to photonic devices. Most existing SPICE photonic models are specialized and fail to capture important features like multi-dimensional signals. It remains a key challenge to represent general photonic devices using SPICE models that include their essential features. To address the above challenge, we separate the signal meaning from its numerical result and adopt a numerically-equivalent approach to construct photonic models using native SPICE primitives. And the designer is left to interpret the meaning of the numerically-equivalent electronic signals, such as wavelength and polarization. Our models encompass the features of existing SPICE models, including wavelength dependence and bi-directional transmission, as well as new features beyond those. Specifically, polarization, optical Kerr effect, two-photon absorption, free carrier absorption, and free carrier dispersion are included in our SPICE models. Closed-loop polarization simulation is realized for the first time. We can quickly achieve frequency-domain simulation by DC sweep instead of stepped frequency transient simulations or frequency chirp-based methods. Our SPICE photonic models show excellent agreement with the simulation results of Verilog-A models and Lumerical models. Our SPICE photonic models are more efficient in co-simulation with SPICE electronic models than Verilog-A photonic models due to less compiling time and better compatibility. Our general models make the circuit design of electronics-photonics convergence (EPC) as convenient as that of traditional integrated circuits, paving the way for the circuit-level convergence of electronics and photonics.

A novel switching-linear hybrid dynamic regulator architecture with dual-supply low dropout regulators (LDOs) is presented in this paper. This architecture leverages the intrinsic dual supplies to extend the operating range of the LDOs. Furthermore, it increases the thermo-optic tuning efficiency by reducing the LDO dropout voltage through dynamic supply modulation. This architecture is suitable for large-scale thermo-optic tuning in silicon photonics. The efficiency improvement is particularly effective when tracking signals of several adjacent channels are close to each other, e.g., wavelength tuning of a microring array. The principle of this architecture is general and can be implemented using different switching converters and LDOs. A specific design with extensive post-layout simulation results is used to verify the effectiveness of our architecture. Implemented in a 130 nm CMOS process, this design can simultaneously regulate eight output channels with an output swing of 0.8$\text V_{\text {pp}}$. Its peak efficiency when driving 100$\Omega $loads is 92% at 1 V output, and the dynamic efficiency is around 86% when tracking 50 kHz sinusoidal signals. To the best of our knowledge, this is the first time that dynamic supply modulation has been applied to multi-channel thermo-optic tuning of silicon photonic devices.

This paper presents a time-division-multiplexed (TDM) clocked-analog low-dropout regulator (CLDO) that shares one controller between multiple output channels. Clocked-analog operation is introduced to create idle periods that enable the shared controller to independently regulate different output channels through time-division multiplexing. Furthermore, an asynchronous transient enhancing technique is presented. Thanks to the controller sharing, the TDM CLDO is more area-efficient than conventional designs for supplying multiple outputs, especially when power stages and on-chip loads are small. To verify the effectiveness of the TDM CLDO, a dual-channel version is fabricated in a 130 nm CMOS process. Measurement results show that it can independently track two 100 kHz 0.3 Vppsinusoidal signals with 4 mV average output error at 100 Ω load and 6 MHz clock frequency. For load transient responses, it can independently regulate two output channels to 1.05 V and 0.95 V with 41 mV/88 mV and 67 mV/39 mV overshoot/undershoot when both channels experience 5 mA current steps at 1.2 Vdd. To the best of our knowledge, this is the first time that hardware sharing is implemented for continuous closed-loop systems.

Visual object recognition under situations in which the direct line-of-sight is blocked, such as when it is occluded around the corner, is of practical importance in a wide range of applications. With coherent illumination, the light scattered from diffusive walls forms speckle patterns that contain information of the hidden object. It is possible to realize non-line-of-sight (NLOS) recognition with these speckle patterns. We introduce a novel approach based on speckle pattern recognition with deep neural network, which is simpler and more robust than other NLOS recognition methods. Simulations and experiments are performed to verify the feasibility and performance of this approach.