Systems and methods for improving output signal quality in memory devices
View Patent ↗A semiconductor device may include a plurality of memory banks and an output buffer that may couple to the plurality of memory banks. The output buffer may produce a data voltage signal representative of data to be read from at least one of the plurality of memory banks to a controller. The semiconductor device may also include a plurality of switches that may couple a voltage source to the output buffer, a first pull-down switch that may drive the output buffer to a low voltage reference level to correct its drive strength. The device also includes a second pull-down switch that may couple the output buffer to the low voltage reference level. The plurality of switches, the first pull-down switch, and the second pull-down switch may each provide the data voltage signal to the output buffer.
1. A semiconductor device, comprising:
a plurality of memory banks;
an output buffer configured to couple to the plurality of memory banks, wherein the output buffer is configured to receive a data voltage signal representative of data to be read from at least one of the plurality of memory banks;
a plurality of switches configured to directly couple a voltage source to the output buffer;
a first pull-down switch configured to directly couple the output buffer to a low voltage reference level, wherein the voltage source and the low voltage reference level are different; and
a second pull-down switch configured to couple the output buffer to the low voltage reference level via a resistor, wherein the plurality of switches, the first pull-down switch, and the second pull-down switch are configured to provide the data voltage signal to the output buffer.
2. The semiconductor device of claim 1 , comprising a logic circuit configured to detect an incoming logical zero of the data and send a first gate signal to the first pull-down switch to cause the first pull-down switch to close in response to the incoming logical zero.
3. The semiconductor device of claim 1 , comprising a logic circuit configured to detect an incoming logical zero of the data and send an indication of the incoming logical zero to a pulse generator.
4. The semiconductor device of claim 3 , wherein the pulse generator is configured to generate a pulse signal configured to cause the second pull-down switch to close for a period of time.
5. The semiconductor device of claim 4 , wherein the pulse signal is configured to cause the second pull-down switch to close synchronously with the first pull-down switch.
6. The semiconductor device of claim 4 , wherein the pulse signal comprises a width determined based on an impedance value associated with the semiconductor device, an upper voltage limit associated with the semiconductor device, a lower voltage limit associated with the semiconductor device, a slew rate associated with the semiconductor device, or any combination thereof.
7. The semiconductor device of claim 4 , wherein the pulse generator is configured to receive the data via a multiplexer.
8. A driver circuit, configured to perform operations comprising:
receiving a first indication that a logical zero is to be provided to an output buffer of a memory device via a data voltage signal representative of data to be written into or read from a plurality of memory banks coupled to the output buffer;
receiving a second indication of a time in which a first pull-down switch configured to directly couple the output buffer to ground is to be closed based on the first indication;
generating a pulse signal configured to cause a second pull-down switch to close synchronously with the first pull-down switch based on the second indication, wherein the second pull-down switch is configured to couple the output buffer to the ground via a resistor;
receiving a third indication that a logical one is to be provided to the output buffer via an additional data voltage signal representative of the data; and
sending a plurality of signals to a plurality of switches configured to directly couple a voltage source to the output buffer in response to receiving the third indication, wherein the voltage source is different from the ground.
9. The driver circuit of claim 8 , wherein the pulse signal comprises a width determined based on an impedance value associated with the output buffer, an upper voltage limit associated with the output buffer, a lower voltage limit associated with the output buffer, a slew rate associated with the output buffer, or any combination thereof.
10. The driver circuit of claim 8 , wherein the pulse signal is configured to cause the second pull-down switch to close for a duration of time.
11. The driver circuit of claim 10 , wherein the duration of time is configured to prevent the data voltage signal from falling below a lower voltage limit associated with the output buffer.
12. The driver circuit of claim 8 , wherein the duration of time is configured to cause the data voltage signal to reach a low voltage value within a half cycle.
13. The driver circuit of claim 8 , wherein the resistor is coupled between the second pull-down switch and the output buffer.
14. The driver circuit of claim 13 , comprising a second resistor coupled between the output buffer and a voltage source, wherein an impedance value of the resistor is determined based on the second resistor.
15. A method, comprising:
receiving, via a circuit, a first indication that a logical zero is to be provided to an output buffer of a memory device via a data voltage signal representative of data to be written into or read from a plurality of memory banks coupled to the output buffer;
receiving, via the circuit, a second indication of a time in which a first pull-down switch configured to directly couple the output buffer to ground is to be closed based on the first indication;
generating, via the circuit, a pulse signal configured to cause a second pull-down switch to close synchronously with the first pull-down switch based on the second indication, wherein the second pull-down switch is configured to couple the output buffer to the ground via a resistor;
receiving a third indication that a logical one is to be provided to the output buffer via an additional data voltage signal representative of the data; and
sending a plurality of gate signals to a plurality of switches configured to directly couple the output buffer to a voltage source in response to receiving the third indication, wherein the plurality of switches is separate from the first pull-down switch and the second pull-down switch.
16. The method of claim 15 , wherein the pulse signal comprises a width determined based on an impedance value associated with the output buffer, an upper voltage limit associated with the output buffer, a lower voltage limit associated with the output buffer, a slew rate associated with the output buffer, or any combination thereof.
17. The method of claim 15 , comprising sending a plurality of additional gate signals to a plurality of switches configured to couple the output buffer to the voltage source in response the memory device being in a standby state, wherein the plurality of additional gate signals is configured to close the plurality of switches.
18. The method of claim 17 , wherein the first pull-down switch and the second pull-down switch are open during the standby state.
19. The method of claim 15 , comprising:
transmitting, via the circuit, a first gate signal to the first pull-down switch, wherein the first gate signal is configured to cause the first pull-down switch to close at a first time;
transmitting, via the circuit, a second gate signal to the second pull-down switch based on the pulse signal, wherein the second gate signal is configured to cause the second pull-down switch to close at the first time.
20. The method of claim 19 , wherein the second gate signal is provided to the second pull-down switch for a duration that corresponds to a width of the pulse signal.