This paper presents a new analog circuit optimization system for automated sizing of analog integrated circuits. It consists of a genetic algorithm (GA)-based global optimization engine and an artificial neural network (ANN)-based local optimization engine. The key new idea is to use parallel computation to train ANN models for design space neighborhoods thus the local minimum search (LMS) can have a much faster search speed. For the GA-based global optimization, circuit performances are calculated by parallel SPICE simulations. For the LMS, circuit performance data are derived from ANN model predictions instead of SPICE simulations. Since most time for an ANN-based LMS is spent on SPICE calls which can be run in parallel, the LMS process can also exploit the multiple core configuration of a modern computational server in addition to the GA global search. The fully parallelized optimization system is deployed to design a two-stage rail-to-rail operational amplifier and a 5th-order active-RC Chebyshev complex band-pass filter. Experimental results show that the proposed method provides about four times speed enhancement and comparable results compared with traditional approaches employing the same parallel global optimization but sequential SPICE calls during LMS.

Terahertz (THz) metasurface biosensors still encounter difficulties in simultaneously achieving high spectral resolution and stable readout across different refractive-index regimes. In this work, an all-liquid-crystal-polymer (LCP) THz metasensor supporting dual quasi-bound states in the continuum (quasi-BIC) resonances is proposed for regime-dependent refractive-index sensing. By introducing structural asymmetry into a periodic LCP cubic-cluster metasurface, two pronounced resonances are generated with quality factors (Q factors) of 6811 and 2526, respectively. Near-field distributions and multipole decomposition analysis indicate that the two resonances possess distinct electromagnetic features, which result in different responses to surrounding dielectric perturbations. In the low-refractive-index range of 1.0–1.5, the two resonance frequencies exhibit a linear variation with refractive index, yielding sensitivities of 122 GHz/RIU and 179 GHz/RIU, respectively. These dual-mode linear responses further offer a foundation for concentration- and temperature-related evaluation through analyte refractive-index mapping. In the higher-refractive-index range of 1.5–1.8, the intermodal frequency difference shows improved linearity with refractive index compared with the individual resonance frequencies, enabling a differential readout scheme with enhanced robustness against common perturbations. The results demonstrate that the proposed all-LCP dual-quasi-BIC metasensor not only enables high-resolution THz refractive-index sensing, but also establishes a regime-dependent spectral readout approach for different dielectric-response intervals.