| CPC H03B 5/1228 (2013.01) [H03B 5/1215 (2013.01); H03B 5/1265 (2013.01); H03B 5/1296 (2013.01); H03L 7/0992 (2013.01); H03L 2207/50 (2013.01)] | 12 Claims |
|
1. An oscillator that functions as a transformer-based LC oscillator including a first capacitor group connected in parallel to a primary-side winding of a transformer and forming a first LC tank together with the primary-side winding, and a second capacitor group connected in parallel to a secondary-side winding of the transformer and forming a second LC tank together with the secondary-side winding, the oscillator comprising:
a first type capacitor bank that is a capacitor bank having a maximum variable capacity of a predetermined value or more, and a second type capacitor bank that is a capacitor bank having a maximum variable capacity of less than the predetermined value, as capacitor banks for oscillation frequency tuning, wherein
the first type capacitor bank is arranged in both of the first capacitor group and the second capacitor group,
each of the first type capacitor bank in the first capacitor group and the first type capacitor bank in the second capacitor group has a plurality of unit cells that are minimum units of variable capacity,
a control unit configured to change an oscillation frequency by performing on/off control of the unit cell on a basis of a frequency control signal indicating a number of capacity change stages is provided, and
when the number of capacity change stages indicated by the frequency control signal is N (N is an integer equal to or greater than 0), the control unit performs, as capacity control based on the frequency control signal, control to turn on (a quotient of N/2) unit cells for the first type capacitor bank in one of the first and second capacitor groups, and turn on N−(a quotient of N/2) unit cells for the first type capacitor bank in other of the first and second capacitor groups.
|