Automatic Op-Amp Generation From Specification to Layout

The operational amplifier is a key building block in analog systems. However, the design process of the operational amplifier is time consuming and heavily depends on engineers’ experiences. This article presents OPAMP-Generator, an analog operational amplifier generator, which automates the full design flow from user-defined specifications to GDSII layout without human intervention. OPAMP-Generator includes behavioral-level topology optimization, efficient sizing algorithm based on the classical
$ {g_{m}/I_{d}}$
design methodology, and automated layout generation. The behavioral-level description of the opamp is represented by the directed acyclic graph (DAG) and a customized variational graph autoencoder is proposed to embed the discrete graph representation into a low-dimensional continuous space. The topology of the opamp can thus be optimized in the latent space, which greatly improves the optimization efficiency. The sizing algorithm based on
${g_{m}/I_{d}}$
methodology can guarantee the quality of transistor-level circuit implementation. The constraints of the layouts can be naturally derived from the topology level, which facilities the automatic generation of layouts. Experimental results demonstrate that our proposed method can efficiently synthesize operational amplifiers with competitive performances compared to manual designs.