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的若干模拟加速器已被提出，用于加速整数量化卷积神经网络的推理，与传统电子加速器相比，其吞吐量和能效显著提高。然而，现有模拟光子加速器存在三个不足：（i）各种串扰效应严重阻碍波长并行性；（ii）除权重固定数据流外，无法灵活支持其他数据流；（iii）未能充分利用光电探测器进行原位累加的能力。这些不足共同限制了先前加速器的性能和能效。为解决这些问题，我们提出了一种名为HEANA的新型混合时间幅度模拟光学加速器。HEANA采用混合时间幅度模拟光学乘法器，增强了其支持多种数据流的灵活性。TAOMs的频谱无干扰排列显著降低了串扰效应，从而提高了HEANA的波长并行性。此外，HEANA采用我们发明的平衡光电累加器，实现无缓冲、原位、时间上的累加，从而无需在HEANA中使用归约网络，消除了相关的延迟和能量开销。我们对四种现代CNN推理的评估表明，在与两种基于MRR的模拟CNN加速器先前工作的等面积比较中，HEANA在每秒帧数和能效上分别至少提升66倍和84倍（基于几何平均值）。