Signal clipping circuit for switched capacitor sigma delta analog to digital converters
AssigneeTexas Instruments Incorporated
InventorRoberto Sadkowski
Life of this patent
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Abstract
A mixed signal CODEC including an improved sigma-delta ADC (20) which limits input signals into a switched capacitor configuration and avoids adding circuit overhead in the signal path is disclosed herein. Additionally, it avoids overshoot and settling problems. This sigma-delta analog-to-digital converter (20), having an input signal and an output signal, includes a switch (sw1), a clipping circuit (21), and a known sigma-delta ADC (34). It solves the clipping signal problem by limiting the signal right at the input of the sigma-delta ADC (34). The clipping circuit (21) couples to the switch (sw1) and the sigma-delta ADC (34) for switching the voltage applied to the sigma-delta ADC between the input signal (vin) and at least one threshold voltage (Vn and Vp).
Claims4
A sigma-delta analog-to-digital converter, having an input signal and an output signal comprising:
- a first switch;
- a clipping circuit coupled to the first switch for switching between the input signal and at least one threshold voltage, the clipping circuit comprises a first branch for clipping the output signal at an upper boundary, and a second branch for clipping the output signal at a lower boundary, the first branch comprises,
- a comparator having an output, a first input coupled to receive a first threshold voltage and a second input coupled to receive the input signal, and
- a second switch coupled to the output of the comparator, the output voltage of the comparator couples to the second switch to open and close the second switch;
- and
- a sigma-delta analog-to-digital converter having an input coupled to the first switch.
A sigma-delta analog-to-digital converter, having an input signal and an output signal comprising:
- a first switch;
- a clipping circuit coupled to the first switch for switching between the input signal and at least one threshold voltage, the clipping circuit comprises a first branch for clipping the output signal at an upper boundary, and a second branch for clipping the output signal at a lower boundary, the second branch comprises,
- a comparator having an output, a first input coupled to receive a first threshold voltage and a second input coupled to receive the input signal, and
- a second switch coupled to the output of the comparator, the output voltage of the comparator couples to the second switch to open and close the second switch;
- and
- a sigma-delta analog-to-digital converter having an input coupled to the first switch.
Dependencies are inferred from the claim text.