In this paper, a 12.5-Gb/s optical transmitter is implemented using 0.13-μm CMOS technology. The optical transmitter that we constructed compensates temperature effects of VCSEL (Vertical cavity surface emitting laser) using auto-power control (APC) and auto-modulation control (AMC). An external monitoring photodiode (MPD) detects optical power and modulation. The proposed APC and AMC demonstrate 5~20-mA of bias-current control and 5~20-mA of modulation-current control, respectively. To enhance the bandwidth of the optical transmitter, an active feedback amplifier with negative capacitance compensation is exploited. The whole chip consumes only 140.4-mW of DC power at a single 1.8-V supply under the maximum modulation and bias currents, and occupies the area of 1280-μm by 330-μm excluding bonding pads.

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This paper proposes a pulse-width modulation-based readout circuit for optical sensors which adopts adaptive frequency control technique to enhance input dynamic range of current sensing systems. The proposed readout circuit is designed and fabricated using a 65 nm CMOS process. The readout IC achieves 100 dB of dynamic range in current sensing system by adaptively controlling the frequency of operating clock.