What is typical leakage reduction percentage by replacing RVT cells with HVT?

[zhipeng]

What is typical leakage reduction percentage by replacing RVT cells with HVT, for a deep sub-micron process?

Looking at the databooks of a 45nm std cell library, it seems cell leakage power of HVT is almost as 1/2 as of RVT. Even if I replace all cells by HVT, the leakage only get reduced by 1/2. Is that normal?

 

[zhipeng]

Case solved.

On this specific process, for leakage reduction, one uses UVT (Ultra-high Threshold Voltage) library, not HVT (High Threshold Voltage), to replace RVT.