Amplifier apparatus, method, and system

The application claimed is a a differential amplifier with is connected to the increase. The differential amplifier with the input transistor and first load transistor comprises a pair of to and second load transistor. The first load transistor the drain electrode of source is connected in the reference voltage and input transistor between two output terminals, and grid is connected with the control voltage. The second load transistor the drain electrode of source is in parallel connected with the first load transistor the drain electrode of source and method. The control circuit, the second load transistor to the gate or with the reference voltage of the second pair of activation), or crossed coupling to transistor connected to the output end (the second pair of activation) is provided for renewable. /Without activate the second load transistor is connected with the activation, switching to the gain of differential amplifier between the high-gain mode and a gain mode sketchily, it can obtain the upper gain by changing the thin adjusting.