US Patent 7569912 Differential variable capacitors and their applications

An integrated circuit design for differential variable capacitors uses an integration method to integrate an integrated circuit having differential variable capacitors as a whole, and takes the parasitic effect into consideration for the manufacturing process to lower the circuit inaccuracy and reduce the chip size effectively. Such arrangement lowers the manufacturing cost, identifies the quality of loading quality of the overall variable capacitance during the manufacture, and further controls the quality of loading capacity of the overall variable capacitance effectively. Furthermore, this invention does not need to reposition for the symmetrical position of the coils, and thus giving a very precise positioning to reduce the level of difficulty for the manufacture.