The previously proposed fast-convergence additive normalization method with exponential convergence rate for computing the exponential function 2 À0:v suffers from high hardware cost for obtaining the normalization factors. Furthermore, when the value of 0:v has many leading-zero bits, the hardware cost of the exponential computation will increase dramatically in order to obtain very high effective precision. In this article, we have first proposed a new method, called efficient fast-convergence additive normalization, to solve the largehardware-cost problem present in the previous fast-convergence method. Then, leading-zero bit detection (LZD) of 0:v is applied to the new efficient fast-convergence method. With this technique, the efficient fast-convergence method can be used to obtain very high effective-precision exponential function at a low hardware cost. We have designed a 24-bit and a 53-bit effective-precision exponential unit using our proposed methods. Thorough simulations of this 24-bit unit have verified that our proposed methods are correct. From our implementation results, we have shown that the proposed efficient fast-convergence method is very effective in improving the cost and speed of the exponential units. Furthermore, we have also shown that the hardware cost of the 48-bit proposed efficient exponential unit can be reduced by about 41% by using the LZD technique. We conclude that our proposed efficient fast-convergence method with LZD technique can very effectively enhance the performance of exponential unit design.