BIAS CIRCUIT FOR MAINTAINING HIGH LINEARITY AT CUTBACK POWER CONDITIONS

摘要

To improve operation during cutback power mode by reducing gain expansion, sections of a multi-section amplifier are selectively biased. During cutback power condition, fewer than all sections of the multi-section amplifier are biased. Selective biasing reduces power consumption and obtains desired output power. To reduce gain expansion, a bias resistor is provided between one or more sections to establish a small or leakage bias current into non-enabled or non-biased sections. This leakage bias current weakly biases the non-enabled sections allowing small signal amplification by the non-enabled sections. The combined amplification of the enabled section and the weakly biased section provide greater initial gain at lower power input signal levels thereby reducing gain expansion.