US Patent 9584090 RF impedance matching network

An RF impedance matching network includes a transformation circuit coupled to an RF input and configured to provide a transformed impedance that is less than a fixed source impedance; a first shunt circuit in parallel to the RF input, the first shunt circuit including a first shunt variable component providing a first variable capacitance or inductance; and a first virtual ground coupled to the first shunt variable component and a ground; and a second shunt circuit in parallel to the RF input and, the second shunt circuit including a second shunt variable component providing a second variable capacitance or inductance; and a second virtual ground coupled to the second shunt variable component and the ground.