Circuits, systems, and methods for synchronization of sampling and sample rate setting
Techniques for synchronization between multiple sampling circuits using a single pin interface to control an output data rate are described. The frequency or rate of a signal on this pin can be automatically determined and used to accomplish the required output data rate. Also described are techniques for using a single pin interface that can allow a sampling device to operate either in a master mode that can generate data strobes, or in a slave mode that can receive a convert start signal. Also described are techniques for controlling bandwidth and throughput for individual channels in a multi-channel device using a single pin interface. For example, using various techniques of this disclosure, integer multiple rate control for other channels can be provided thereby providing varying ODR for different channels, which can also control the bandwidth of interest.
1. A system for synchronizing a plurality of sampling channels, the system comprising:
a single output data rate (ODR) terminal configured to receive a desired ODR signal representing an ODR,
a synchronization circuit configured to receive the desired ODR signal and a first clock signal and output a second clock signal synchronized to the ODR signal and output a data signal representing a relationship of the ODR to a frequency of the first clock signal; and
at least one of the plurality of sampling channels, the at least one of the plurality of sampling channels including:
a sampling circuit configured to receive a respective analog input signal and the first clock signal and output a sampled signal based on the analog input signal at a rate based on the frequency of the first clock signal; and
a rate setting circuit configured to receive the sampled signal, the data signal, and the second clock signal and output a digital signal representative of the respective analog input signal at the output data rate.
2. The system of claim 1 , wherein the plurality of sampling channels are located in a plurality of sampling devices.
3. The system of claim 2 , wherein the plurality of sampling devices are located on the same circuit board.
4. The system of claim 1 , comprising:
a master/slave control circuit configured to receive a respective master/slave input signal representing a desired operating mode, and generate a control data signal to the synchronization circuit based on the desired operating mode,
wherein, in a master mode, the synchronization circuit is configured to output on the single ODR terminal the second clock signal synchronized to the desired ODR signal, and
wherein, in a slave mode, the at least one sampling device is configured to receive the desired ODR signal on the single ODR terminal.
5. The system of claim 4 , comprising:
a data serializer circuit configured to receive the digital signal output by the rate setting circuit and generate serialized data based on the digital signal and generate a serialized data clock signal.
6. The system of claim 1 , comprising:
a plurality of the sampling channels,
wherein the synchronization circuit configured to output a second clock signal synchronized to the desired ODR signal and output a data signal representing a relationship of the ODR to the frequency of the first clock signal is configured to:
output a plurality of second clock signals synchronized to the desired ODR signal and output a plurality of data signals, each of the plurality of data signals representing a relationship of the ODR to the frequency of the first clock signal;
wherein each of the plurality of rate setting circuits is configured to:
receive a respective one of the plurality of second clock signals and a respective one of the plurality of data signals, and
output a digital signal representative of the respective analog input signal at a respective output data rate.
7. The system of claim 6 , wherein the plurality of second clock signals includes at least first and second groups of second clock signals, wherein the first group of second clock signals has a different frequency than the second group of second clock signals, wherein the plurality of data signals includes at least first and second groups of data signals, and wherein the first group of data signals is different than the second group of data signals.
8. The system of claim 6 , wherein the at least one of the plurality of sampling devices includes:
a master/slave control circuit configured to receive a respective master/slave input signal representing a desired operating mode, and generate a control data signal to the synchronization circuit based on the desired operating mode,
wherein the desired ODR signal includes data representing a multiple of the ODR for each of the plurality of sampling channels,
wherein the synchronization circuit configured to output a plurality of second clock signals synchronized to the desired ODR signal and output a plurality of data signals, each of the plurality of data signals representing a relationship of the ODR to the frequency of the first clock signal is configured to:
output, based on the control data signal, a plurality of second clock signals synchronized to the desired ODR signal and output a plurality of data signals, each of the plurality of data signals representing a relationship of the ODR to the frequency of the first clock signal.
9. The system of claim 1 , wherein the synchronization circuit includes:
a digital phase locked loop circuit configured to receive the desired ODR signal and output the second clock signal; and
a data calculation circuit configured to receive the first clock signal and output the data signal.
10. The system of claim 1 , wherein the sampling circuit includes:
a sigma delta analog to digital converter having a sigma delta modulator circuit and a decimation filter circuit.
11. The system of claim 1 , wherein the sampling circuit includes:
a successive approximation register (SAR) analog to digital converter.
12. The system of claim 1 , wherein the frequency of the first clock signal is higher than a frequency of the second clock signal and a frequency of the ODR.
13. The system of claim 1 , wherein the data signal representing a relationship of the ODR to a frequency of the first clock signal is a ratio data signal representing a ratio of the ODR to a frequency of the first clock signal.
14. A system for synchronizing a plurality of sampling channels, the system comprising:
means for receiving a desired ODR signal representing an ODR;
means for receiving the desired ODR signal and a first clock signal;
means for outputting a second clock signal synchronized to the ODR signal and outputting a data signal representing a relationship of the ODR to a frequency of the first clock signal;
means for receiving a respective analog input signal and the first clock signal and outputting a sampled signal based on the analog input signal at a rate based on the frequency of the first clock signal; and
means for receiving the sampled signal, the data signal, and the second clock signal and outputting a digital signal representative of the respective analog input signal at the output data rate.
15. A method for synchronizing a plurality of sampling channels, the method comprising:
receiving, via a single output data rate (ODR) terminal, a desired ODR signal representing an ODR;
receiving, via a synchronization circuit, the desired ODR signal and a first clock signal;
outputting, via the synchronization circuit, a second clock signal synchronized to the ODR signal and outputting a data signal representing a relationship of the ODR to a frequency of the first clock signal;
receiving, via a sampling circuit, a respective analog input signal and the first clock signal and outputting a sampled signal based on the analog input signal at a rate based on the frequency of the first clock signal; and
receiving, via a rate setting circuit, the sampled signal, the data signal, and the second clock signal and outputting a digital signal representative of the respective analog input signal at the output data rate.
16. The method of claim 15 , comprising:
receiving, via a master/slave control circuit, a respective master/slave input signal representing a desired operating mode, and generating a control data signal based on the desired operating mode,
when in a master mode, outputting on the single ODR terminal the second clock signal synchronized to the desired ODR signal, and
when in a slave mode, receiving the desired ODR signal on the single ODR terminal.
17. The method of claim 16 , comprising:
receiving, via a data serializer circuit, the digital signal output and generating serialized data based on the digital signal and generating a serialized data clock signal.
18. The method of claim 15 , wherein outputting a second clock signal synchronized to the desired ODR signal and outputting a data signal representing a relationship of the ODR to the frequency of the first clock signal includes:
outputting a plurality of second clock signals synchronized to the desired ODR signal and outputting a plurality of data signals, each of the plurality of data signals representing a relationship of the ODR to the frequency of the first clock signal;
receiving, via each of the plurality of rate setting circuits, a respective one of the plurality of second clock signals and a respective one of the plurality of data signals; and
outputting a digital signal representative of the respective analog input signal at a respective output data rate.
19. The method of claim 18 , wherein the plurality of second clock signals includes at least first and second groups of second clock signals, wherein the first group of second clock signals has a different frequency than the second group of second clock signals, wherein the plurality of data signals includes at least first and second groups of data signals, and wherein the first group of data signals is different than the second group of data signals.
20. The method of claim 18 , comprising:
receiving, via a master/slave control circuit, a respective master/slave input signal representing a desired operating mode, and generating a control data signal based on the desired operating mode,
wherein the desired ODR signal includes data representing a multiple of the desired ODR signal for each of the plurality of sampling channels;
wherein outputting a plurality of second clock signals synchronized to the desired ODR signal and outputting a plurality of data signals, each of the plurality of data signals representing a relationship of the ODR to the frequency of the first clock signal includes:
outputting, based on the control data signal, a plurality of second clock signals synchronized to the desired ODR signal and outputting a plurality of data signals, each of the plurality of data signals representing a relationship of the ODR to the frequency of the first clock signal.