Narrow Results

The influence of pump direction in all-optical gain-clamped fiber Raman amplifier using the directional couplers in feedback loop is demonstrated. The isolator direction decided the lasing direction in feedback loop. The comparison of performance in two lasing directions for both schemes is shown. It is concluded that the forward pumping configuration with forward lasing has better gain clamping performance and noise performance.

In this paper, a CMOS active down-conversion mixer is presented for wideband applications. Specifically, a LO generation chain is suggested to convert AC LO signal to shaped trapezoid burst, which reduces the sinusoidal LO power level requirement by the mixer. The current-reuse technique by stacked nMOS/pMOS architecture is used to save the power consumption of the circuit. Moreover, this complementary configuration is also employed to compensate second-order nonlinearity of the circuit. Implemented in a 0.18-$\mu$m CMOS process, post-simulations show that, driven by only −10 dBm sinusoidal LO signal, the proposed inductorless mixer provides a maximal conversion gain of 15.7 dB and a noise figure (NF) of 9.1–12 dB across RF input frequency range 0.5–1.6 GHz. The IIP3 and IP1dB of 3.5 dBm and −4.8 dBm are obtained, respectively. The mixer core only consumes 3.6 mW from a 1.8-V supply.