Design of Multiple Feedback-Based Low-Noise Amplifier With Improved Broadband Simultaneous Noise and Impedance Matching Technique

A multiple feedback-based technique is presented to improve broadband simultaneous noise and impedance matching (BSNIM) performance in a GaAs low-noise amplifier (LNA). It consists of dual reactive feedback for the first stage and frequency-dependent feedback loops (FDFLs) for the succeeding stages. Compared to existing BSNIM technologies, the proposed method completes the theoretical derivation of the required load and can provide flexible solutions, which effectively increases the optimization opportunity. Besides, in order to achieve the required load, a structure composed of low- ${Q}$ high order LC-ladder networks and FDFLs are introduced, which greatly reduce the difficulty of impedance conversion. The detailed strategies for BSNIM are also given. To verify feasibility, a 6–14 GHz three-stage common-source LNA has been fabricated via 0.15- $\mu \text{m}$ GaAs pHEMT process, with a measured gain of $26.8 \pm 0.75$ dB, a minimum noise of 1.21 dB, and $S_{11}$ of less than −15 dB throughout the entire operating band.