Patent ID: 7312669

Claim:
An oscillation circuit for generating a first output signal and a second output signal that have a frequency f and are different in phase from each other by π/2 radian, comprising: an original oscillator that is a ring oscillator oscillating at a frequency f/n (n represents an integer of 2 or more), and output intermediate signals S(k) (k represents an integer satisfying 1≦k≦4n) of 4n each having a phase difference of (k−1)π/2n [rad] from a reference phase from nodes of 4n provided in an oscillation loop; a first multiplying portion for generating a first mixed signal corresponding to the product of the intermediate signals S(k 1j ) of n (j represents an integer satisfying 1≦j≦n, and each k 1j represents any integer from 1 to 4n) and generating the first output signal on the basis of the first mixed signal; and a second multiplying portion for generating a second mixed signal corresponding to the product of the intermediate signals S(k 2j ) of n for k 2j satisfying the following equation and generating the second output signal on the basis of the second mixed signal: ∑ j = 1 n ⁢ ⁢ k 2 ⁢ j = ∑ j = 1 n ⁢ ⁢ k 1 ⁢ j + n .