Low voltage, low power sensing based on level shifting sensing circuit
A sensing circuit for sensing an analog signal includes a level shifter that shifts the analog signal from a high voltage domain to a low voltage domain. The signal originates from the high voltage domain, and is passed to the low voltage domain through the level shifter. A source line provides the analog signal, which can be selectively switched into a sense amplifier circuit. The sense amplifier is in the low voltage domain and generates a digital output to represent the sensed analog signal.
1. An apparatus comprising:
a source line to provide an analog signal;
a level shifter to shift the analog signal from a high voltage domain to a low voltage domain;
a sense amplifier in the low voltage domain to sense the analog signal in the low voltage domain and generate a digital output to represent the analog signal;
a sense amplifier switch to selectively couple the sense amplifier to an output of the level shifter; and
a precharge switch to discharge the output of the level shifter and then float the output of the level shifter prior to the sense amplifier switch selectively coupling the sense amplifier to the output of the level shifter.
2. The apparatus of claim 1 , wherein the level shifter comprises a capacitor.
3. The apparatus of claim 2 , wherein the capacitor comprises a high voltage transistor.
4. The apparatus of claim 1 , wherein control signals to control operation of the sense amplifier comprise signals in the low voltage domain.
5. The apparatus of claim 1 , wherein the analog signal in the low voltage domain has a lower voltage than a swing of the digital output.
6. The apparatus of claim 1 , further comprising:
a reference signal generator in the low voltage domain to provide a reference signal for the low voltage domain to the sense amplifier.
7. The apparatus of claim 6 , wherein the reference signal generator comprises a trim generator to generate a trim value to center the reference signal on a mean of the analog signal.
8. A system, comprising:
a nonvolatile memory cell; and
a sensing circuit to sense the nonvolatile memory cell, including:
a source line to provide an analog signal from the nonvolatile memory cell;
a level shifter to shift the analog signal from a high voltage domain to a low voltage domain;
a sense amplifier in the low voltage domain to sense the analog signal in the low voltage domain and generate a digital output to represent the analog signal;
a sense amplifier switch to selectively couple the sense amplifier to an output of the level shifter; and
a precharge switch to discharge the output of the level shifter and then float the output of the level shifter prior to the sense amplifier switch selectively coupling the sense amplifier to the output of the level shifter.
9. The system of claim 8 , wherein the level shifter comprises a capacitor.
10. The system of claim 9 , wherein the capacitor comprises a high voltage transistor.
11. The system of claim 8 , wherein control signals to control operation of the sense amplifier comprise signals in the low voltage domain.
12. The system of claim 8 , wherein the analog signal in the low voltage domain has a lower voltage than a swing of the digital output.
13. The system of claim 8 , wherein the nonvolatile memory cell comprises a three dimensional (3D) crosspoint memory cell.
14. The system of claim 8 , wherein the nonvolatile memory cell comprises a NAND (not AND) memory cell.
15. The system of claim 8 , further comprising one or more of:
a host processor device coupled to the nonvolatile memory cell;
a display communicatively coupled to a host processor;
a network interface communicatively coupled to a host processor; or
a battery to power the system.
16. The system of claim 8 , the sensing circuit further comprising:
a reference signal generator in the low voltage domain to provide a reference signal for the low voltage domain to the sense amplifier.
17. The system of claim 16 , wherein the reference signal generator comprises a trim generator to generate a trim value to center the reference signal on a mean of the analog signal.
18. A method for sensing a signal, comprising:
discharging an output of a level shifter;
receiving an analog signal in a low voltage domain, from the level shifter that shifts the analog signal from a high voltage domain to the low voltage domain;
floating the output of the level shifter;
sensing the analog signal with a sense amplifier in the low voltage domain; and
generating a digital output in the low voltage domain to represent the analog signal.
19. The method of claim 18 , further comprising:
connecting a reference signal generator to the sense amplifier in the low voltage domain to provide a reference signal for the low voltage domain.
20. The method of claim 18 , wherein the sense amplifier includes a first transistor to couple to a high rail of the low voltage domain and a second transistor to couple to a low rail of the low voltage domain, and further comprising:
switching the first transistor and the second transistor one after another in time with control signals in the low voltage domain.
21. The method of claim 18 , wherein sensing the analogy signal with the sense amplifier comprises comparing the output of the level shifter in the low voltage domain to a reference signal generated in the low voltage domain.