Switched Capacitor Signal Circuit for Common-Mode Cancellation

The circuit performs two alternating phases: a non-swapping phase and a swapping phase. In the non-swapping phase, the circuit operates with normal capacitor connections to process the sensing signal. In the swapping phase, the switch groups swap the connections of the compensation capacitors and input capacitors. By alternating between these phases and averaging the results, the system periodically varies the capacitor connections to eliminate the effect of mismatch, achieving complete common-mode cancellation despite process variations.

The invention changes the connection parameters of the capacitors dynamically through the switch groups. During the swapping phase, the physical connections of the compensation capacitors and input capacitors are exchanged, effectively changing which capacitor is connected to which node. This parameter change allows the system to measure and compensate for capacitor mismatches, resolving the reliability issue of incomplete cancellation caused by fixed mismatched connections.

Instead of using complex mismatched capacitors with precise matching, the invention maintains simple capacitor structures and instead introduces periodic swapping action. The switch groups exchange capacitor connections between two phases, allowing the system to achieve precise common-mode cancellation through temporal averaging rather than through spatial precision of matched components.

The switch groups act as intermediaries that dynamically reconfigure the capacitor connections. These switches enable the system to transition between different connection states without requiring the capacitors themselves to be precisely matched, thereby maintaining circuit simplicity while achieving high precision common-mode rejection through controlled reconfiguration.