A low noise, wide dynamic range, transimpedance amplifier with automatic gain control for SDH/SONET (STM16/OC48) in a 30GHz fTBiCMOS process

The paper presents a transimpedance amplifier (TIA) with automatic gain control for SDH/SONET (STM16/OC48) fibre optic applications. It features independent gain control, de-coupled from the bandwidth, wide dynamic range (5µA÷1.7mA) and high sensitivity (-24dBm). The equivalent input noise is typically 8pA/√Hz while the bandwidth of the amplifier is 1.9GHz (worst-case). The AGC regulates the differential transimpedance from 4kΩ at low currents (<50µApp) to 80Ω at high currents (>500/µApp). The amplifier remains linear up to 1.7mA and can withstand photodiode input currents up to 2.5mA. The typical power consumption of the amplifier is 85mW (3.3V supply) and the active area is about 0.72mm². It is realized in a 30GHz fTBiCMOS process (Qubic3).