Patent ID: 7042292

Claim:
A radio communication apparatus comprising: a mixer that mixes a radio frequency signal with a local oscillation carrier to produce an intermediate frequency signal; an amplifier that adjusts the signal level of said intermediate frequency signal, said amplifier having a control voltage supply circuit and a variable gain circuit, wherein: said control voltage supply circuit uses an external control voltage to generate an internal control voltage, said control voltage supply circuit generates said internal control voltage in response to said external control voltage as to compensate for linearity of said variable gain circuit to an extent of said external control voltage where said variable gain circuit loses said linearity, said internal control voltage relative to said external control voltage from a first reference voltage to a second reference voltage is different from when said external control voltage is less than said first reference voltage or exceeds said second reference voltage, said variable gain circuit has an uncompensated gain characteristic and a compensated gain characteristic, said uncompensated gain characteristic relative to said external control voltage is linear from said first reference voltage to said second reference voltage, and is non-linear when said external control voltage is less than said first reference voltage or exceeds said second reference voltage, said variable gain circuit uses said internal control voltage to produce a compensated gain characteristic, said compensated gain characteristic relative to said external control voltage being linear from said first reference voltage to said second reference voltage, and being linear when said external control voltage is less than said first reference voltage or exceeds said second reference voltage; and a base band IC demodulates and decodes said adjusted intermediate frequency signal.