Several photonic microring resonators (MRRs) based analog accelerators have been proposed to accelerate the inference of integer-quantized CNNs with remarkably higher throughput and energy efficiency compared to their electronic counterparts. However, the existing analog photonic accelerators suffer from three shortcomings: (i) severe hampering of wavelength parallelism due to various crosstalk effects, (ii) inflexibility of supporting various dataflows other than the weight-stationary dataflow, and (iii) failure in fully leveraging the ability of photodetectors to perform in-situ accumulations. These shortcomings collectively hamper the performance and energy efficiency of prior accelerators. To tackle these shortcomings, we present a novel Hybrid timE Amplitude aNalog optical Accelerator, called HEANA. HEANA employs hybrid time-amplitude analog optical multipliers (TAOMs) that increase the flexibility of HEANA to support multiple dataflows. A spectrally hitless arrangement of TAOMs significantly reduces the crosstalk effects, thereby increasing the wavelength parallelism in HEANA. Moreover, HEANA employs our invented balanced photo-charge accumulators (BPCAs) that enable buffer-less, in-situ, temporal accumulations to eliminate the need to use reduction networks in HEANA, relieving it from related latency and energy overheads. Our evaluation for the inference of four modern CNNs indicates that HEANA provides improvements of atleast 66x and 84x in frames-per-second (FPS) and FPS/W (energy-efficiency), respectively, for equal-area comparisons, on gmean over two MRR-based analog CNN accelerators from prior work.

翻译：基于光子微环谐振器（MRR）的模拟加速器已被提出用于加速整数量化CNN的推理，其吞吐量和能效均显著优于电子对应方案。然而，现有模拟光子加速器存在三个缺陷：(i) 多种串扰效应严重阻碍波长并行性；(ii) 除权重固定数据流外，无法灵活支持多种数据流；(iii) 未能充分利用光电探测器进行原位累加的能力。这些缺陷共同制约了前期加速器的性能与能效。为克服上述问题，我们提出一种新型混合时间-幅度模拟光学加速器HEANA。HEANA采用混合时间-幅度模拟光学乘法器（TAOM），增强了加速器支持多种数据流的灵活性。TAOM的光谱无冲突排布显著降低了串扰效应，从而提升了HEANA的波长并行性。此外，HEANA采用我们发明的平衡光电累加器（BPCA），实现无缓冲原位时间累加，消除了HEANA对归约网络的需求，避免了相关延迟与能耗开销。针对四个现代CNN推理的评估表明，在与两种基于MRR的模拟CNN加速器（前期工作）进行等面积对比时，HEANA在几何平均下使帧率（FPS）和能效（FPS/W）分别提升至少66倍和84倍。