Abstract: In this work we describe phase modulators for several Mach-Zehnder interferometers (MZI) on silicon nitride platform for telecomm wavelength (1550 nm). We obtained current-voltage and phase-voltage curves for these modulators. MZI are needed for experimental realisation of various quantum receivers that can distinguish weak coherent states of light with extremely low error. Thermo-optical (TO) modulation is ensured by microheaters on one of the arms of MZI, which enables the change of the refractive index of the material with temperature. This approach allows to apply the necessary voltage to the golden microheaters to obtain the required phase change. For the on-chip microheaters we demonstrate the dependence of the phase shift on the voltage applied to our on-chip microheaters.