Noise and Parasites in Mixed Circuits

This work investigates substrate-coupling effects in mixed IC’s, specially the perturbations on RF blocks. The design and analysis of fully integrated radiofrequency Voltage Controlled Oscillators (VCOs) are key points in RF analysis. First of all, the oscillation frequency sensitivity functions of tuning voltage, bias current and spurious side-bands due to injected noise are extracted to find out some relation between substrate noise and spectrum purity.

In the goal to realize quantum nanometric devices, for instance, based on a resonant tunneling effect through the Si/SiO2 interface, we model SiO2/Si/SiO2 double barriers embedded between two n-doped Si layers. To study the quantum confinement in Si QW we have solved a set of coupled Schrödinger–Poisson equations simultaneously.

In the core of the paper, we try to develop quantitative predictions about the phase noise of such oscillators, and to give some new tracks in this field.

Mixed mode simulations are involved by applying a microscopic Drift Diffusion Model to the device, while the Kirchhoff’s laws govern the rest of the circuit used.

Another problem field for the designers of complex heterogeneous circuits is to predict the perturbations coming from commutating logical gates blocks, flowing through the substrate to reach some sensitive analog blocks. We present an application of a stochastic process model; the digital switching activity is handled as functions defined as Markov Chains.

Keywords: Mixed circuits, radiofrequencies, 3D, parasites, noise propagation, substrate coupling, ground or supply bounces, oscillators, theory, modeling, phase noise, sensitivity functions, resonant tunnelling, stochastic process.