They borrowed his ideas bc they didn’t want one person or group to have all the power like the king of England at the time; therefore having 3 different branches and separated power was the solution
The founding Fathers were heavily influenced by the ideas of the French philosopher who wrote in his ‘Spirit of Laws’ that the inevitability to delegate commands and power is imperative as it would prevent any branch to become too authoritative while formulating and executing federal policies.
This aspect of Separation of Powers enthused US to formulate its own Constitution which encompassed two major aspects: delegation of powers, checks and balances.
This French philosopher belonged to the period of Enlightenment. He believed that when power is equally deputized there will not be any domination of one particular branch over the other.
Lucius Cornelius Sulla the Roman dictator was the one responsible for the dramatic changer in Roman consitution. Sulla's politics was rather conservative, and Sulla had an objective to strengthen the Roman Senate and reduce the power of the plebeian tribunes. He retired in 79BC.