Patent ID: 7269402

Claim:
A communication apparatus comprising a circuit device having an oscillating means for oscillating in a plurality of frequency bands, a signal generating means which includes said oscillating means for generating an oscillation signal according to desired frequency information, wherein said circuit device comprising: a power source means for generating a DC voltage as a control voltage of said oscillating means, when the frequency of said oscillating means increases in accordance with increasing of said control voltage of said oscillating means, said DC voltage having reverse dependence to dependence of said oscillating means in frequency relative to temperature in the case, when the frequency of said oscillating means decreases in accordance with increasing of said control voltage of said oscillating means, said DC voltage having the same dependence as dependence of said oscillating means in frequency relative to temperature in the case, a counter means for measuring an oscillation frequency of said oscillating means; a storage means for storing frequency information measured per each frequency band of said oscillating means by said counter means; and a control means for performing calibration by connecting said oscillating means to said power source means, oscillating said oscillating means in accordance with one of said DC voltage supplied from said power source means, measuring this oscillation frequency per each frequency band of said oscillating means by said counter means, and storing the oscillation frequency in said storage means.