Patent ID: 8076912
Filing Date: 2011-12-13
Classification: H02M

Abstract:
1. A semiconductor integrated circuit configured to control a MEMS-type variable capacitance capacitor having primary electrodes with a MEMS structure for frequency modulation and auxiliary electrodes for changing the distance between the primary electrodes to change the capacitor's electrostatic capacitance, the semiconductor integrated circuit comprising: a first pump circuit configured to generate a first voltage for decreasing the distance between the primary electrodes; a first limiter circuit configured to limit the first voltage to a first predetermined limit; a second pump circuit configured to generate a second voltage for keeping the distance between the primary electrodes constant and having first supplying capacity; a second limiter circuit configured to limit the second voltage generated by the second pump circuit to a second predetermined limit; a third pump circuit configured to generate the second voltage and having second supplying capacity lower than the first supplying capacity; a third limiter circuit configured to limit the second voltage generated by the third pump circuit to a predetermined limit; and a ripple capacitor configured to suppress ripple of the second voltage; wherein the ripple capacitor is charged up to the second voltage by the second pump circuit and the second limiter circuit within a period of time the first voltage is being generated by the first pump circuit and the first limiter circuit, and wherein, when a supplying voltage of the first pump circuit reaches to the first voltage and a deformation of the MEMS-type variable capacitance capacitor stops, the second voltage is supplied by the third pump circuit and the third limiter circuit instead of the second pump circuit and the second limiter circuit.