Patent ID: 7812662

Claim:
A voltage regulation module, comprising: an adjustable voltage regulator having first and second outputs providing a positive supply voltage and a negative supply voltage, respectively, and having a mode control input for receiving a mode select signal; wherein said adjustable voltage regulator asserts said positive supply voltage at a first core voltage level and said negative supply voltage at a second core voltage level when said mode select signal indicates a higher power state, and wherein said adjustable voltage regulator reduces said positive supply voltage and increases said negative supply voltage when said mode select signal indicates a lower power state; a bias generator which provides an N-type substrate bias voltage at said first core voltage level, which provides a P-type substrate bias voltage at said second core voltage level during said lower power state, wherein said bias generator has a first input receiving said positive supply voltage, a second input receiving said negative supply voltage, and a third input receiving said mode select signal; wherein said adjustable voltage regulator reduces voltage of said positive supply voltage by a first offset voltage to provide a reduced positive supply voltage and increases voltage of said negative supply voltage by a second offset voltage to provide an increased negative supply voltage during said lower power state; and wherein said bias generator adds said first offset voltage to said reduced positive supply voltage to provide said N-type substrate bias voltage during said lower power state and wherein said bias generator subtracts said second offset voltage from said increased negative supply voltage by to provide said P-type substrate bias voltage during said lower power state.