Method and system for a track and hold amplifier with extended dynamic range
Systems and methods for a track and hold amplifier with extended dynamic range may include a track amplifier comprising a first PMOS transistor coupled to a first NMOS transistor, a second PMOS transistor coupled to a second NMOS transistor, a capacitor at gates of each NMOS and PMOS transistor, and a plurality of switches. The track and hold amplifier is operable to, during a tracking mode of the track and hold amplifier, couple a differential input signal to each NMOS and PMOS transistor via a first switch coupled to a first capacitor coupled to the gate of the first PMOS transistor and a second capacitor coupled to the gate of the first NMOS transistor, and via a second switch coupled to a third capacitor coupled to the gate of the second PMOS and a fourth capacitor coupled to the gate of the second NMOS transistor.
1. A method for communication, the method comprising:
in a track and hold amplifier comprising a first PMOS transistor coupled to a first NMOS transistor, a second PMOS transistor coupled to a second NMOS transistor, a capacitor at a gate terminal of each NMOS and PMOS transistor, and a plurality of switches:
during a tracking mode of the track and hold amplifier:
operatively coupling a differential input signal to each NMOS and PMOS transistor via a first switch coupled to a first capacitor coupled to the gate terminal of the first PMOS transistor and a second capacitor coupled to the gate terminal of the first NMOS transistor, and via a second switch coupled to a third capacitor coupled to the gate terminal of the second PMOS transistor and a fourth capacitor coupled to the gate terminal of the second NMOS transistor;
operatively coupling the gate terminal of the first PMOS transistor to the gate terminal of the second PMOS transistor via a third switch;
operatively coupling the gate terminal of the first NMOS transistor to the gate terminal of the second NMOS transistor via a fourth switch;
operatively coupling a first common mode voltage to the gate terminals of the first and second PMOS transistors; and
operatively coupling a second common mode voltage to the gate terminals of the first and second NMOS transistors.
2. The method according to claim 1 , comprising shunting first and second output terminals together using a fifth switch during the tracking mode of the track and hold amplifier.
3. The method according to claim 2 , comprising during a holding mode of the track and hold amplifier:
opening the first, second, third, and fourth switches;
decoupling the first common mode voltage from the first and second PMOS transistors and the second common mode voltage from the first and second NMOS transistors;
operatively coupling the first and second capacitors to the first output terminal of the track and hold amplifier via a sixth switch; and
operatively coupling the third and fourth capacitors to the second output terminal of the track and hold amplifier via a seventh switch.
4. The method according to claim 1 , comprising generating one or more of the first and second common mode voltages using one or more switched capacitor feedback loops.
5. The method according to claim 4 , wherein the one or more switched capacitor feedback loops comprises a plurality of capacitors, a plurality of switches, and a first amplifier.
6. The method according to claim 5 , wherein a fifth capacitor is operatively coupled to a first output terminal of the track and hold amplifier and a sixth capacitor is operatively coupled to a second output terminal of the track and hold amplifier.
7. The method according to claim 5 , wherein an output voltage of the first amplifier in each of the one or more switched capacitor feedback loops comprises a common mode voltage for the track and hold amplifier.
8. The method according to claim 1 , wherein the first common mode voltage is operatively coupled to the gate terminals of the first and second PMOS transistors via a first pair of switches.
9. The method according to claim 8 , wherein the second common mode voltage is operatively coupled to the gate terminals of the first and second NMOS transistors via a second pair of switches.
10. The method according to claim 1 , wherein the track and hold amplifier is integrated in one or more complementary metal oxide semiconductor (CMOS) die.
11. The method according to claim 10 , wherein the one or more CMOS die receives an optical signal that is converted to an electrical signal that is coupled to the track and hold amplifier.
12. A system for communication, the system comprising:
a track and hold amplifier comprising a first PMOS transistor coupled to a first NMOS transistor, a second PMOS transistor coupled to a second NMOS transistor, a capacitor at a gate terminal of each NMOS and PMOS transistor, and a plurality of switches, the track and hold amplifier being operable to:
during a tracking mode of the track and hold amplifier:
operatively couple a differential input signal to each NMOS and PMOS transistor via a first switch coupled to a first capacitor coupled to the gate terminal of the first PMOS transistor and a second capacitor coupled to the gate terminal of the first NMOS transistor, and via a second switch coupled to a third capacitor coupled to the gate terminal of the second PMOS transistor and a fourth capacitor coupled to the gate terminal of the second NMOS transistor;
operatively couple the gate terminal of the first PMOS transistor to the gate terminal of the second PMOS transistor via a third switch;
operatively couple the gate terminal of the first NMOS transistor to the gate terminal of the second NMOS transistor via a fourth switch;
operatively couple a first common mode voltage to the gate terminals of the first and second PMOS transistors; and
operatively couple a second common mode voltage to the gate terminals of the first and second NMOS transistors.
13. The system according to claim 12 , wherein the track and hold amplifier is integrated in one or more complementary metal oxide semiconductor (CMOS) die.
14. The system according to claim 12 , wherein the first common mode voltage is operatively coupled to the gate terminals of the first and second PMOS transistors via a first pair of switches.
15. The system according to claim 12 , wherein first and second output terminals of the track and hold amplifier are shunted together using a fifth switch during the tracking mode of the track and hold amplifier.
16. The system according to claim 12 , wherein during a holding mode, the track and hold amplifier is operable to:
open the first, second, third, and fourth switches;
decouple the first common mode voltage from the first and second PMOS transistors and the second common mode voltage from the first and second NMOS transistors;
operatively couple the first and second capacitors to a first output terminal of the track and hold amplifier via a sixth switch; and
operatively couple the third and fourth capacitors to a second output terminal of the track and hold amplifier via a seventh switch.
17. The system according to claim 12 , wherein one or more of the first and second common mode voltages are generated using one or more switched capacitor feedback loops.
18. The system according to claim 17 , wherein each of the one or more switched capacitor feedback loops comprises a plurality of capacitors, a plurality of switches, and a first amplifier.
19. The system according to claim 18 , wherein an output voltage of the first amplifier in each of the one or more switched capacitor feedback loops comprises a common mode voltage for the track and hold amplifier.
20. The system according to claim 18 , wherein a fifth capacitor is operatively coupled to a first output terminal of the track and hold amplifier and a sixth capacitor is operatively coupled to the second output terminal of the track and hold amplifier.
21. The system according to claim 19 , wherein the second common mode voltage is operatively coupled to the gate terminals of the first and second NMOS transistors via a second pair of switches.
22. A system for communication, the system comprising:
a track and hold amplifier comprising a first PMOS transistor coupled to a first NMOS transistor, a second PMOS transistor coupled to a second NMOS transistor, a capacitor at a gate terminal of each NMOS and PMOS transistor, and a plurality of switches, the track and hold amplifier being operable to, during a tracking mode of the track and hold amplifier:
operatively couple a differential input signal to each NMOS and PMOS transistor via a first switch coupled to a first capacitor coupled to the gate terminal of the first PMOS transistor and a second capacitor coupled to the gate terminal of the first NMOS transistor, and via a second switch coupled to a third capacitor coupled to the gate terminal of the second PMOS transistor and a fourth capacitor coupled to the gate terminal of the second NMOS transistor;
operatively couple the gate terminal of the first PMOS transistor to the gate terminal of the second PMOS transistor via a third switch;
operatively couple the gate terminal of the first NMOS transistor to the gate terminal of the second NMOS transistor via a fourth switch; and
short first and second output terminals of the track and hold amplifier together via a fifth switch;
operatively couple a first common mode voltage from a first switched feedback loop to the gate terminals of the first and second PMOS transistors; and
operatively couple a second common mode voltage from a second switched capacitor feedback loop to the gate terminals of the first and second NMOS transistors.