The improved mutual impedance amplifier to produce output voltage from one input current includes one current buffer to increase the bandwidth of the amplifier, one current amplifier to produce relatively high mutual impedance for the amplifier, and one I/V amplifier. The current amplifier contains one current mirror and one current source and the current buffer contains one buffering transistor and one differential amplifier. The improved mutual impedance amplifier is very useful, especially in CD and DVD-ROM pick-up circuit. |