Invention Grant
US08471744B1 Reduced residual offset sigma delta analog-to-digital converter (ADC) with chopper timing at end of integrating phase before trailing edge 有权
减少残差偏移Σ-Δ模数转换器(ADC),在后沿积分相位结束时具有斩波定时

Reduced residual offset sigma delta analog-to-digital converter (ADC) with chopper timing at end of integrating phase before trailing edge
Abstract:
An analog-to-digital converter (ADC) has a chopper-stabilized sigma-delta modulator (SDM). The SDM uses switched-capacitor integrators to sample, hold, and integrate an analog input in response to non-overlapping multi-phase clocks. Chopper multipliers are inserted on the inputs and outputs of an op amp in a first stage integrator. The chopper multipliers swap or pass through differential inputs in response to non-overlapping chopper clocks. A master clock operating at a frequency of the multi-phase clocks is divided down to trigger generation of the chopper clocks. Delay lines ensure that the edges of the chopper clocks occur before the edges of the multi-phase clocks. The chopper multipliers have already switched and are thus stable when multi-phase clocks change so charge injection at switches controlled by the multi-phase clocks is not immediately modulated by chopper multipliers. This clock timing increases the time available to respond to charge injection at switches improving linearity.
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