Patent ID: 7269399

Claim:
A receiver of double conversion system comprising: an antenna tuning circuit including a tuning coil and a variable-capacitance diode; a high frequency amplification circuit for performing high frequency amplification for a signal outputted from said antenna tuning circuit; first and second mixing circuits for performing frequency conversion twice for an output of said high frequency amplification circuit; a detecting circuit for performing detection processing for an output of said second mixing circuit; a digital-analog converter for generating a control voltage for setting a tuning frequency applied to said variable-capacitance diode included in said antenna tuning circuit; a local oscillator for inputting a local oscillation signal whose frequency is variable to said first mixing circuit to which an output signal of said high frequency amplification circuit is inputted; and a control section for setting the frequency of the local oscillation signal outputted from said local oscillator, and for generating a frequency setting data required for associating the tuning frequency of said antenna tuning circuit with the frequency of the local oscillation signal, and for inputting the frequency setting data to said digital-analog converter, wherein said digital-analog converter comprises a temperature coefficient setting section constituted by including elements having predetermined temperature coefficients, wherein a device constant of said temperature coefficient setting section as a whole is changed in accordance with ambient temperature, wherein said digital-analog converter, said high frequency amplification circuit, said first and second mixing circuits, said detecting circuit and said local oscillator are formed on a same semiconductor substrate wherein said temperature coefficient setting section includes a plurality of resistances which are formed by a semiconductor manufacturing process and which have temperature coefficients different to each other, and wherein a connection form of said plurality of resistances is set so that a temperature coefficient of said digital-analog converter reaches a predetermined value.