Design of Σ-Δ Modulator for Monolithic Integrated Thermal Vacuum Sensors
Zhen Tang · 2010
A 2nd-order single-bit Σ-Δ modulator was designed for integrated thermal vacuum sensor,in which feed-forward paths were adopted to restrain output swing,reduce harmonic distortion and improve dynamic range.Correlated double-sampling circuit was used in the integrator to reduce 1/f noise of the operational amplifier.Effects of non-idealities of the op-amp on the modulator were analyzed with Matlab/Simulink.The modulator was realized by using fully differential switched capacitor circuit.Simulation results showed that the circuit had a peak SNR of 86.9 dB and a 14-bit of resolution at 4 MHz sampling rate and 6.8 kHz input frequency for-3 dBFS amplitude.Consuming 12 mW of power from 3 V supply voltage,the Σ-Δ modulator occupies an active area of 0.67 mm2.And all specifications meet the design target.