Active low-power termination
An active termination circuit comprising an input node connected to a transmission line, a first transistor, and a second transistor. The transmission line supplies a signal to the input node. The first transistor is diode connected between a high voltage supply and the input node. The first transistor terminates the signal when the signal is at a low logic level. The second transistor is diode connected between the input node and a low voltage supply. The second transistor terminates the signal when the signal is at a high logic level.
1. An active termination circuit comprising:
an input node connected to a transmission line configured to supply a signal to the input node;
a first transistor diode connected between a high voltage supply and the input node, the first transistor configured to terminate the signal in response to the signal being at a low logic level, wherein a first control gate of the first transistor is connected to the high voltage supply; and
a second transistor diode connected between the input node and a low voltage supply, the second transistor configured to terminate the signal in response to the signal being at a high logic level, wherein a second control gate of the second transistor is connected to the low voltage supply.
2. The active termination circuit of claim 1 , further comprising an inherent bias on terminals of the first transistor and the second transistor such that each transistor operates alternately within a saturation region and a cut-off region as the signal transitions between the high logic level and the low logic level.
3. The active termination circuit of claim 1 , wherein the first transistor and the second transistor are calibrated to provide a dynamic termination impedance to the signal on the transmission line within a target input impedance range, wherein the dynamic termination impedance changes as the signal transitions between the low logic level and the high logic level.
4. The active termination circuit of claim 1 , wherein at least one of the first transistor and the second transistor are calibrated to provide a termination impedance to the signal on the transmission line within a target input impedance range based on a temperature range that the active termination circuit is configured to operate in.
5. The active termination circuit of claim 1 , wherein the first transistor comprises an NPN bipolar transistor and the second transistor comprises a PNP bipolar transistor and the high voltage supply is less than or equal to 1.4 volts.
6. The active termination circuit of claim 1 , wherein the first transistor operates in a saturation region and the second transistor operates in a cut-off region in response to the signal having the low logic level and the second transistor operates in the saturation region and the first transistor operates in the cut-off region in response to the signal having the high logic level.
7. The active termination circuit of claim 1 , wherein a strength of at least one of the first transistor and the second transistor is configurable.
8. An active termination circuit comprising:
an input node connected to a transmission line configured to supply a signal to the input node;
a first transistor diode connected between a high voltage supply and the input node, the transistor configured to terminate the signal in response to the signal being at a low logic level; and
a second transistor diode connected between the input node and a low voltage supply, the second transistor configured to terminate the signal in response to the signal being at a high logic level, wherein the first transistor comprises an NMOS transistor and the second transistor comprises a PMOS transistor.
9. The active termination circuit of claim 8 , wherein the PMOS transistor comprises a set of PMOS transistors configured to be coupled in parallel with the input node and low voltage supply based on calibration settings that determine which PMOS transistors of the set of PMOS transistors are coupled in parallel.
10. An active termination circuit comprising:
an input node connected to a transmission line configured to supply a signal to the input node;
a first transistor diode connected between a high voltage supply and the input node, the transistor configured to terminate the signal in response to the signal being at a low logic level; and
a second transistor diode connected between the input node and a low voltage supply, the second transistor configured to terminate the signal in response to the signal being at a high logic level, wherein the first transistor comprises a set of transistors configured to connect in parallel by way of a set of switches, the set of switches set to one of an open state and a closed state based on a calibration setting.
11. An active termination circuit comprising:
an input node connected to a transmission line configured to supply a signal to the input node;
a first transistor diode connected between a high voltage supply and the input node, the transistor configured to terminate the signal in response to the signal being at a low logic level; and
a second transistor diode connected between the input node and a low voltage supply, the second transistor configured to terminate the signal in response to the signal being at a high logic level, wherein the second transistor comprises a set of transistors configured to connect in parallel by way of a set of switches, the set of switches set to one of an open state and a closed state based on a calibration setting.
12. A system, comprising:
a first integrated circuit mounted on a printed circuit board;
a second integrated circuit mounted on the printed circuit board;
an interconnect configured to operate as a transmission line transmitting signals between the first integrated circuit and the second integrated circuit; and
an active termination circuit formed within one of the first integrated circuit and the second integrated circuit, the active termination circuit comprising:
an input node configured to connect to the interconnect and configured to receive a signal from the interconnect;
an NMOS transistor having a gate terminal and a drain terminal each connected to a high voltage supply and a source terminal connected to the input node, the NMOS transistor configured to terminate the signal in response to the signal being in a low logic level; and
a PMOS transistor having a gate terminal and a drain terminal each connected a low voltage supply and a source terminal connect to the input node, the PMOS transistor configured to terminate the signal in response to the signal being in a high logic level.
13. The system of claim 12 , wherein the NMOS transistor and the PMOS transistor of the active termination circuit are calibrated to provide a dynamic termination impedance to the signal from the interconnect, wherein the dynamic termination impedance changes as the signal transitions between the low logic level and the high logic level and the NMOS transistor and PMOS transistor comprise an inherent bias that exists as the NMOS transistor and the PMOS transistor transition alternately between a saturation region and a cut-off region.
14. The system of claim 12 , wherein the first integrated circuit is a non-volatile memory storage controller and the second integrated circuit is a non-volatile memory die controller.
15. The system of claim 12 , wherein the first integrated circuit is a non-volatile memory storage controller and the second integrated circuit is a uniform memory die;
the system further comprising a stack of uniform memory dies each uniform memory die coupled to each other in series by a wire bond; and
wherein the active termination circuit is within each uniform memory die of the stack of uniform memory dies.
16. The system of claim 12 , further comprising:
a temperature sensor configured to sense a temperature for one of the first integrated circuit and the second integrated circuit;
a storage controller configured to:
store a set of calibration settings for one or more of the NMOS transistor and the PMOS transistor, the set of calibration settings used to calibrate one of the NMOS transistor and the PMOS transistor; and
change calibration settings for one of the NMOS transistor and the PMOS transistor in response to the temperature sensor sensing a temperature below or above a temperature threshold.
17. The system of claim 16 , wherein the storage controller is further configured to change calibration settings for the PMOS transistor in response to the temperature sensed by the temperature sensor being greater than or equal to about 100° C. and less than or equal to about −25° C.
18. A method for calibrating an active termination circuit, the method comprising: receiving a target input impedance range (Rin) for an active termination circuit, the active termination circuit comprising:
an NMOS transistor diode connected between a high voltage supply and an input node; and
a PMOS transistor diode connected between the input node and a low voltage supply;
measuring an input impedance as an input current (Ln), applied to the input node, transitions between a high logic level and a low logic level;
determining whether the measured input impedance falls within the target input impedance range; and
calibrating a strength for one of the NMOS transistor and the PMOS transistor in response to the input impedance falling outside the target input impedance range.
19. The method of claim 18 , wherein:
one of the NMOS transistor and the PMOS transistor comprises a set of transistors, each of a common transistor type, configured to connect in parallel by way of a set of switches set to one of an open state and a closed state based on a calibration setting; and
wherein calibrating the strength for one of the NMOS transistor and the PMOS transistor comprises changing the calibration setting such that one or more additional transistors from the set of transistors is connected in parallel as one of the NMOS transistor and the PMOS transistor.
20. The method of claim 18 , wherein calibrating the strength for one of the NMOS transistor and the PMOS transistor comprises adjusting a strength of one of the NMOS transistor and the PMOS transistor based on an operating temperature range for the active termination circuit.