Systems and methods for signal sampling using a sampling array

1 . A system comprising:

a capacitive sampling array having an input interface, an output interface, and capacitive sampling channels connected in parallel between the input interface and the output interface, wherein each capacitive sampling channel has a channel-specific capacitor having a channel-specific capacitance;

a readout system coupled to the output interface of the capacitive sampling array and configured to generate digital data in response to a signal received on the input interface of the capacitive sampling array; and

a controller coupled to the readout system to receive the digital data and configured to select capacitive sampling channels of the capacitive sampling array to sample the signal in response to the digital data.

2 . The system of claim 1 , wherein the controller is configured to change a pattern of sampling instances in a frame of sampling instances in response to a magnitude of the signal received on the input interface, wherein a sampling instance includes a selected capacitive sampling channel.

3 . The system of claim 2 , wherein the controller is further configured to:

change a capacitive sampling channel of a sampling instance in the frame to a capacitive sampling channel with a smaller capacitance in response to a portion of the signal that has a higher magnitude than a previous portion of the signal; and

change a capacitive sampling channel of a sampling instance in the frame to a capacitive sampling channel with a larger capacitance in response to a portion of the signal that has a lower magnitude than a previous portion of the signal.

4 . The system of claim 2 , wherein the controller is further configured to:

select a capacitive sampling channel with a smaller capacitance to correspond to a portion of the signal with a higher magnitude; and

select a capacitive sampling channel with a larger capacitance to correspond to a portion of the signal with a lower magnitude.

5 . The system of claim 1 , wherein the controller is configured to select a capacitive sampling channel from the capacitive sampling channel array for a subsequent sampling instance in response to a magnitude of the signal received on the input interface.

6 . The system of claim 5 , wherein the controller is further configured to:

select a capacitive sampling channel for a subsequent sampling instance that has a larger capacitance than a previous sampling instance in response to digital data that indicates a rising edge of the signal; and

select a capacitive sampling channel for a subsequent sampling instance that has a smaller capacitance than a previous sampling instance in response to digital data that indicates a falling edge of the signal.

7 . The system of claim 1 , wherein the channel-specific capacitors of each capacitance sampling channel is a function of a unit capacitor.

8 . The system of claim 7 , wherein a first capacitive sampling channel in the capacitive sampling array has more unit capacitors than a second capacitive sampling channel array such that the first capacitive sampling channel has a larger capacitance than the second capacitive sampling channel.

9 . The system of claim 1 , wherein the capacitive sampling channels of the capacitive sampling array include channel-specific switches that enable the capacitive sampling channels to be individually activated for sampling the input signal.

10 . The system of claim 1 , wherein the controller is further configured to:

increase a sampling rate of the system in response to a portion of the signal that has a higher magnitude; and

decrease the sampling rate of the system in response to a portion of the signal that has a lower magnitude.

11 . A method comprising:

obtaining a sample of a signal from a capacitive sampling array having an input interface, an output interface, and capacitive sampling channels connected in parallel between the input interface and the output interface, wherein each capacitive sampling channel has a channel-specific capacitor having a channel-specific capacitance;

selecting a capacitive sampling channel from the capacitive sampling array for a subsequent sampling instance in response to the sample; and

controlling the capacitive sampling array to sample the signal in the subsequent sampling instance using the selected capacitive sampling channel.

12 . The method of claim 11 , wherein selecting a capacitive sampling channel from the capacitive sampling array for a subsequent sampling instance in response to the sample involves changing a pattern of sampling instances in a frame of sampling instances in response to a magnitude of the signal, wherein a sampling instance includes a selected capacitive sampling channel.

13 . The method of claim 12 , further comprising:

changing a capacitive sampling channel of a sampling instance in the frame to a capacitive sampling channel with a smaller capacitance in response to a portion of the signal has a higher magnitude than a previous portion of the signal; and

changing a capacitive sampling channel of a sampling instance in the frame to a capacitive sampling channel with a larger capacitance in response to a portion of the signal that has a lower magnitude than a previous portion of the signal.

14 . The method of claim 11 , wherein selecting a capacitive sampling channel from the capacitive sampling array for a subsequent sampling instance in response to the sample involves:

selecting a capacitive sampling channel with a smaller capacitance to correspond to a portion of the signal with a higher magnitude; and

selecting a capacitive sampling channel with a larger capacitance to correspond to a portion of the signal with a lower magnitude.

15 . The method of claim 11 , wherein selecting a capacitive sampling channel from the capacitive sampling array for a subsequent sampling instance in response to the sample involves selecting a capacitive sampling channel from the capacitive sampling channel array for a subsequent sampling instance in response to a magnitude of the signal received on the input interface.

16 . The method of claim 15 , further comprising:

selecting a capacitive sampling channel for a subsequent sampling instance that has a smaller capacitance than a previous sampling instance in response to digital data that indicates a rising edge of the signal; and

selecting a capacitive sampling channel for a subsequent sampling instance that has a larger capacitance than a previous sampling instance in response to digital data that indicates a falling edge of the signal.

17 . A method for operating a system that samples an input signal, the method comprising:

selecting capacitive sampling channels with large channel-specific capacitance from a capacitive sampling array to sample portions of a signal that have low magnitude; and

selecting capacitive sampling channels with small channel-specific capacitance from the capacitive sampling array to sample portions of the signal that have high magnitude;

wherein the capacitive sampling array includes an input interface to receive the signal, an output interface, and capacitive sampling channels connected in parallel between the input interface and the output interface, wherein each capacitive sampling channel has a channel-specific capacitor having a channel-specific capacitance; and

wherein the large channel-specific capacitance has larger capacitance than the small channel-specific capacitance, and the portions of the signal that have low magnitude have lower magnitude than the portions of the signal that have high magnitude.

18 . The method of claim 17 , wherein the capacitive sampling channels are selected in response to digital data generated in response to samples of the signal generated by the capacitive sampling array.