Bias control technique for CDMA driver amplifier to decrease current

The ACPR requirement is constant over wide power range. ACPR at lower output power is excessive in conventional constant bias current. A new bias control technique to decrease bias current at lower power level is proposed by implementing hyperbolic tangent function (tanh) with offsets. It is verified indirectly by measurement. The measured bias current is reduced by the amount of 22% over the control range compared to the conventional one, in addition to meeting the ACPR requirement simultaneously over the entire range of output power.