A new type of miniature pressure sensor using silicon/Pyrex capacitive sensing cell and a BiCMOS analog–digital integrated circuit has been realised, modelled and characterised. Its digital output realised by a differential counting system permits to minimise thermal drifts and non-linearity. A hybrid demonstrator has been implemented with a ceramic capacitor as reference to evaluate the feasibility. It is characterised by a relative sensitivity close to −2.7%/bar, a non-linearity in the order of 0.78% of the full scale, and a thermal zero shift smaller than 150 ppm/°C. A simple analytical model validated by PSPICE simulations and experimental data has permitted to evaluate sensor behaviour but also influences of different parameters as leakage current or stray capacitors that induce a decrease in sensitivity and contribute to higher non-linearity. Some comparisons between different model results have permitted to evaluate parasitic parameter values and their temperature behaviour. Moreover, experimental visualisations of output signals also point out some interference between oscillators that induce worst accuracy. PSPICE modelling has permitted to localise causes and then to propose a simple solution to minimise these problems.