Wide division ratio range programmable frequency divider with close-to-50% output duty-cycle

Abstract

A novel wide division ratio (DR) range programmable frequency divider is presented in this article, which is based on the proposed divide-by-2/3/4 cell. The divider's output is buffered by a divide-by-2 cell; hence, it can achieve the close-to-50% output duty-cycle. The DRs can be set via the convenient provisions of binary bits. When the DR is even, the output duty-cycle is exactly 50%. If the DR is odd, the output duty-cycle is k/(2 k + 1), where k is a natural number, therefore, it becomes close-to-50% with an increasing k. A divider with eight DR control bits, which can realise the DRs from 8 to 511, is implemented in standard 0.18 µm complementary metal-oxide semiconductor technology, the die area is 0.02 mm2. The measured results show that the divider can obtain 44.4–50% output duty-cycle which corroborates with the calculation.