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ERNIE-4.5-21B-A3B-Base

Active Parameters

21B

Context Length

131K

Modality

Text

Architecture

Mixture of Experts (MoE)

License

Apache 2.0

Release Date

30 Jun 2025

Knowledge Cutoff

Dec 2024

System Requirements

VRAM requirements for different quantization methods and context sizes

1,024 tokens

45.66 GB VRAM

Consumer

2x RTX 4090

24GB VRAM

Datacenter

1x NVIDIA A100

80GB VRAM

Apple Silicon

1x Apple M3 Max

128GB VRAM

131,072 tokens

53.49 GB VRAM

Consumer

3x RTX 4090

24GB VRAM

Datacenter

1x NVIDIA A100

80GB VRAM

Apple Silicon

1x Apple M3 Max

128GB VRAM

Architecture Diagram

Input TokensToken EmbeddingPosition: AbsoluteHidden: 2.6k · Context: 131K · Vocab: 103.4kx 28 layersRMSNormPre-AttentionGrouped-Query Attention20Q / 4KV headsHead dim: 128+RMSNormPre-FFNSparse MoE FFN (6/64 experts)SwiGLUIntermediate: 1.5k+Final RMSNormOutput Logits

Evaluation Benchmarks

No evaluation benchmarks for ERNIE-4.5-21B-A3B-Base available.

Rankings

Overall Rank

-

Coding Rank

-

About ERNIE-4.5-21B-A3B-Base

The ERNIE-4.5-21B-A3B-Base model is a text-focused Mixture-of-Experts (MoE) transformer and a core component of Baidu's ERNIE 4.5 model family. This specific variant is derived through a process of modality-specific extraction, where text-related parameters are isolated from a larger multimodal pre-training phase that incorporates trillions of tokens. Its architecture is characterized by a heterogeneous MoE structure that supports parameter sharing across modalities during training while maintaining dedicated experts for specific data types. This design ensures that textual representations are not compromised by multimodal joint training, allowing for high-performance natural language understanding and generation in both Chinese and English.

Technically, the model employs a sparse architecture featuring 64 experts per layer, with a routing mechanism that activates 6 experts per token, resulting in approximately 3 billion active parameters per forward pass. This sparsity provides a significant reduction in computational overhead while maintaining the representative capacity of a much larger 21-billion parameter model. The attention mechanism utilizes Grouped-Query Attention (GQA) with 20 query heads and 4 key-value heads, which optimizes memory bandwidth and inference speed. The integration of 2D Rotary Position Embeddings (RoPE) and support for a 131,072-token context window makes it highly effective for processing long-form documents and complex reasoning tasks.

To facilitate efficient deployment, the ERNIE 4.5 family is built on the PaddlePaddle framework and incorporates several hardware-level optimizations, including FP8 mixed-precision training and multi-expert parallel collaboration. The model supports advanced quantization techniques such as 4-bit and 2-bit lossless compression, enabling it to run on diverse hardware platforms with reduced memory requirements. By utilizing modality-isolated routing and specialized router losses, the model achieves high parameter efficiency, making it suitable for industrial-grade applications ranging from sophisticated summarization to cross-modal reasoning within a production environment.

Technical Specifications

Attention

Attention Structure

Grouped-Query Attention

Attention Heads

20

Key-Value Heads

4

Attention Head Dimension

128

Position Embedding

Absolute Position Embedding

RoPE Theta

500,000

Sliding Window Attention

No

Sliding Window Size

-

Sliding Window Ratio

-

Linear Attention

-

Linear Attention Ratio

-

Normalization

RMS Normalization

Activation Function

SwigLU

Dimensions

Hidden Dimension Size

2,560

Number of Layers

28

FFN Intermediate Size (Dense)

1,536

Multi-Token Prediction Heads

-

Tokenizer

Vocabulary Size

103,424

Mixture of Experts

Total Expert Parameters

3.0B

Number of Experts

64

Active Experts

6

Shared Experts

2

FFN Intermediate Size (per Expert)

1,536

Dense Layers Before MoE

1

About ERNIE 4.5

The Baidu ERNIE 4.5 family consists of ten large-scale multimodal models. They utilize a heterogeneous Mixture-of-Experts (MoE) architecture, which enables parameter sharing across modalities while also employing dedicated parameters for specific modalities, supporting efficient language and multimodal processing.


Other ERNIE 4.5 Models