In this paper we present a technique for constraint allocation in analog system synthesis. Constraint allocation is the process of assigning constraint budgets to the sub-systems so that the user asserted system level constraints are satisfied. Our approach is based on the formulation of the constraint allocation problem as a constraint satisfaction problem (CSP) and solving it. The solution method employed uses interval techniques to check for the satisfiability of the CSP. The generation of the exact set of solutions is done by an interval reduction and instantiation mechanism. We also discuss the constraint allocation mechanism in the context of a mixed-signal synthesis system. Finally, we present a design example to validate the constraint allocation technique.