Why Gated DeltaNet Survives 4-Bit Quantization: NVFP4 W4A4 for the Recurrent Half of a Hybrid 27B LLM

TL;DR - Minima quantizes every linear layer of a 27B hybrid LLM—including its recurrent Gated DeltaNet layers—to NVFP4 W4A4 while retaining near-BF16 quality. The results challenge the assumption that recurrent layers require higher precision and provide a practical recipe for smaller, faster inference.

• Minima occupies 17.5 GiB, improves prefill speed by 14–19%, and scores within seed noise of BF16 across language, reasoning, coding, and long-context evaluations.
• NVFP4’s 16-element block scaling localizes activation outliers, while nonlinear gate parameterizations reduce roughly 11% projection error to about 2% output error.
• GDN’s delta-rule recurrence prevents quantization noise from compounding: noise plateaus over 32K tokens, and injected state errors are forgotten within hundreds of steps.
• The work fixes scale mismatches in fused serving kernels and recommends quantizing all linear layers while shipping calibrated FP8 KV-cache scales.