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A low-power offset-cancellation switched capacitor bandgap reference for a tyre pressure monitor system is proposed. It employs a correlated double sampling switched-capacitor amplifier with opamp offset voltage cancellation without requiring the output to slew to ground each time the amplifier is reset. Additionally the circuit topology is very insensitive to low opamp gain and allows a simple single-stage opamp structure. This structure also has clock feedthrough cancellation and is very suitable for low-power application owing to its small slew rate and low opamp gain requirement. Moreover, coarse and fine process calibration techniques are applied to minimise the process deviation. Simulation results are provided to verify the effectiveness of the topology.
Date of Publication: July 5 2012