Invention Grant
US07693494B2 High dynamic range pre-power amplifier incorporating digital attenuator 有权
包含数字衰减器的高动态范围前置功率放大器

High dynamic range pre-power amplifier incorporating digital attenuator
Abstract:
A novel digital attenuator circuit and associated pre-power amplifier (PPA) that substantially increases the dynamic range of the amplifier. Increased dynamic range is achieved by placing a digital current attenuator circuit at the output of the pre-power amplifier so that the minimum possible current output of the transistor switch array of the PPA can be further attenuated. The attenuator functions to split the current between the load and the power supply VDD (i.e. AC ground) based on device ratio that is controlled digitally via an input power control word. The digital attenuator is constructed as a segmented digitally controlled matrix or cell array comprising at least a pass and bypass matrix or array. The pass matrix controls the amount of current output from the PPA while the bypass matrix controls the amount of current shorted to the AC ground (i.e. power supply). By varying the number of transistors on or off in each matrix, the power output of the PPA can be easily and accurately controlled.
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