Methods and apparatuses for turning on and off an ADC driver in an ultrasound device

1. An ultrasound device, comprising:

control circuitry; and

an analog-to-digital converter (ADC) driver coupled to the control circuitry;

wherein the control circuitry is configured to:

turn on and off the ADC driver; and

control a ratio between a current in the ADC driver when the ADC driver is turned off and a current in the ADC driver when the ADC driver is turned on.

2. The ultrasound device of claim 1 , wherein the control circuitry is configured to turn on and off the ADC driver in synchronization with sampling activity of an ADC.

3. The ultrasound device of claim 1 , wherein the control circuitry is configured to turn on and off the ADC driver based on when an ADC is sampling.

4. The ultrasound device of claim 1 , wherein the control circuitry is configured to control a duty cycle of the ADC driver turning on and off.

5. The ultrasound device of claim 4 , wherein the control circuitry is configured to control the duty cycle of the ADC driver turning on and off by selecting a duty cycle value from among multiple possible duty cycle values.

6. The ultrasound device of claim 5 , where the multiple possible duty cycle values comprise three or more possible duty cycle values.

7. The ultrasound device of claim 1 , wherein the control circuitry is configured to control the ratio between the current in the ADC driver when the ADC driver is turned off and the current in the ADC driver when the ADC driver is turned on by selecting the ratio from among multiple possible ratio values.

8. The ultrasound device of claim 7 , where the multiple possible ratio values comprise three or more possible ratio values.

9. The ultrasound device of claim 1 , wherein the control circuitry is configured to control a value of a current in the ADC driver when the ADC driver is turned on.

10. The ultrasound device of claim 1 , wherein the control circuitry is configured to control a value of a current in the ADC driver when the ADC driver is turned off.

11. The ultrasound device of claim 10 , wherein the control circuitry is configured to control the value of the current in the ADC driver when the ADC driver is turned off by selecting the value from among multiple possible values.

12. The ultrasound device of claim 11 , where the multiple possible values comprise three or more possible values.

13. The ultrasound device of claim 1 , wherein the ADC driver comprises:

a transistor receiving an input analog signal;

a current source; and

a switch coupled between the transistor and the current source;

wherein the control circuitry is configured to turn off the ADC driver by opening the switch.

14. The ultrasound device of claim 1 , wherein the ADC driver comprises:

a transistor receiving an input analog signal;

a first current source;

a second current source;

a first switch coupled between the transistor and the first current source; and

a second switch coupled between the transistor and the second current source;

wherein the control circuitry is configured to turn off the ADC driver by opening either the first switch, the second switch, or both the first and second switches.

15. The ultrasound device of claim 1 , wherein the ADC driver comprises:

a first transistor receiving an input analog signal;

a current source; and

a second transistor coupled between the first transistor and the current source;

wherein the control circuitry is configured to turn off the ADC driver by turning off the second transistor.

16. The ultrasound device of claim 1 , wherein the ADC driver comprises:

a first transistor receiving an input analog signal;

a first current source;

a second current source;

a second transistor coupled between the first transistor and the first current source; and

a third transistor coupled between the first transistor and the second current source;

wherein the control circuitry is configured to turn off the ADC driver by turning off the second transistor, the third transistor, or both the second and third transistors.

17. The ultrasound device of claim 16 , wherein the control circuitry is configured to turn off the second transistor, the third transistor, or both the second and third transistors by switching a signal at a gate of the second transistor, the third transistor, or both the second and third transistors from high to low or from low to high.

18. The ultrasound device of claim 1 , further comprising:

an ADC coupled to an output of the ADC driver and configured to:

sample an analog ultrasound signal; and

convert the analog ultrasound signal to digital subsequent to sampling the analog ultrasound signal;

wherein the control circuitry is configured to turn on and off the ADC driver by turning on the ADC driver prior to the ADC sampling the analog ultrasound signal and to turn off the ADC driver prior to the ADC converting the analog ultrasound signal.

19. An ultrasound device, comprising:

control circuitry;

an analog-to-digital converter (ADC) driver coupled to the control circuitry;

wherein the control circuitry is configured to turn on and off the ADC driver;

an ADC coupled to an output of the ADC driver and configured to operate with a track phase and a hold phase; and

wherein the control circuitry is configured to turn on and off the ADC driver by turning on the ADC driver during the hold phase a first time period before the track phase and by turning off the ADC driver during the hold phase a second time period after the track phase.

20. The ultrasound device of claim 1 , wherein the ultrasound device comprises an ultrasound-on-chip.