At the end of the Second World War, a new technological trend was born: integrated electronics. This trend relied on the enormous rise of integrable electronic devices. Analog Devices and Circuits is composed of two volumes: the first deals with analog components, and the second with associated analog circuits. The goal here is not to create an overly comprehensive analysis, but rather to break it down into smaller sections, thus highlighting the complexity and breadth of the field. The second volume deals with the circuits that "use" the analog components that were introduced in Volume 1. Here, a particular emphasis is placed on the main circuit: the operational amplifier. SPICE (Simulation Program with Integrated Circuit Emphasis) is the standard for simulating analog circuits. Anyone who does not know this does not belong to the fraternity of electronic circuit analogists. SPICE is therefore the essential software for studying analog circuits. The Chapter 2 investigates substrate coupling effects in mixed integrated circuits, particularly perturbations on radiofrequency (RF) blocks. The design and analysis of fully integrated voltage-controlled oscillators (VCOs) is one of the key points of RF analysis. First, sensitivity functions at the oscillation frequency of the control voltage, the bias current and parasitic sidebands due to the injected noise are extracted to discover a relationship between the noise of the substrate and the purity of the spectrum. At the heart of the section, we try to develop quantitative predictions on the phase noise of these oscillators and give new leads in this field.