Patent ID: 6806775
Filing Date: 2004-10-19
Classification: H03F

Abstract:
A power amplifier circuit comprising:an amplifying part transistor including a bipolar transistor to which a first supply voltage is supplied as a driving voltage and which amplifies an input signal inputted to a base of the amplifying part transistor so as to output the input signal; a bias current generating circuit which generates a bias current for biasing the base of the amplifying part transistor and supplies the bias current to the base of the amplifying part transistor when the amplifying part transistor performs an amplification operation; and an additional bias current generating circuit which supplies an additional bias current to the base of the amplifying part transistor in addition to the bias current according to the first supply voltage, wherein the first supply voltage is supplied to a collector of the amplifying part transistor, and a second supply voltage whose value is equivalent to that of the first supply voltage is supplied to the additional bias current generating circuit, and wherein the additional bias current generating circuit supplies the additional bias current when the second supply voltage is higher than a predetermined value but the additional bias current generating circuit does not supply the additional bias current when the second supply voltage is lower than the predetermined value.