  Let $\Gamma$ be a finite group acting faithfully and linearly on a vector
space $V$. Let $T(V)$ ($S(V)$) be the tensor (symmetric) algebra associated to
$V$ which has a natural $\Gamma$ action. We study generalized quadratic
relations on the tensor algebra $T(V)\rtimes \Gamma$. We prove that the
quotient algebras of $T(V)\rtimes \Gamma$ by such relations satisfy PBW
property. Such quotient algebras can be viewed as quantizations of linear or
constant Poisson structures on $S(V)\rtimes \Gamma$, and are natural
generalizations of symplectic reflection algebras.
