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An optical sensor with variable transimpedance for optical storage systems in 0.6 μm BiCMOS technology is presented. A PIN photodiode, a voltage-controlled current amplifier, and a current-to-voltage converter are monolithically integrated. A balanced type of the BJT translinear loop based voltage-controlled current amplifier is used. A linearity error smaller than 3.6%, a transimpedance dynamic range of 8323 (78.4 dB) with the largest transimpedance of 12.9 MΩ, a maximum photo-sensitivity of 6824 mV/μW at 675 nm, an offset voltage below 2.2 mV, a maximum power consumption of 9.1 mW, a bandwidth up to 463 MHz, a transimpedance bandwidth product up to 285 TΩHz, and an output noise power down to -72.5 dBm (at 50 MHz and a resolution bandwidth of 30 kHz) are achieved.