Pass gate driver
A driver includes a low-resistance charging path between a supply voltage rail and a first output node, a high-resistance charging path between the supply voltage rail and the first output node, an inverter coupled to the first output node and configured to enable and disable the low-resistance charging path, and a high-resistance discharging path between the first output node and a second output node. The first output node is coupled to a control terminal of a pass gate transistor in some implementations. The low-resistance charging path charges a voltage on the first output node to a threshold voltage of the pass gate transistor, and the high-resistance charging path charges the voltage on the first output node greater than the threshold voltage of the pass gate transistor. The high-resistance discharging path discharges the voltage on the first output node.
1. A driver circuit, comprising:
a first transistor having a first control terminal coupled to an input node, a first current terminal coupled to a supply voltage rail, and a second current terminal;
a second transistor having a second control terminal configured to receive a first biasing voltage, a third current terminal coupled to the second current terminal, and a fourth current terminal coupled to a first output node;
a third transistor having a third control terminal configured to receive a second biasing voltage, a fifth current terminal coupled to the first output node, a sixth current terminal;
a fourth transistor having a fourth control terminal coupled to the input node, a seventh current terminal coupled to the sixth current terminal, and an eighth current terminal coupled to a second output node;
a fifth transistor having a fifth control terminal, a ninth current terminal coupled to the second and third current terminals, and a tenth current terminal;
a sixth transistor having a sixth control terminal configured to receive the first biasing voltage, an eleventh current terminal coupled to the tenth current terminal, and a twelfth current terminal coupled to the first output node;
a first inverter, comprising:
a seventh transistor having a seventh control terminal coupled to the first output node, a thirteenth current terminal coupled to the supply voltage rail, and a fourteenth current terminal; and
an eighth transistor having an eighth control terminal coupled to the first output node, a fifteenth current terminal coupled to the fourteenth current terminal, and a sixteenth current terminal coupled to the second output node; and
a second inverter having an input coupled to the fourteenth and fifteenth current terminals and an output coupled to the fifth control terminal.
2. The driver circuit of claim 1 , wherein the first output node is configured to be coupled to a control terminal of a pass gate transistor, and wherein characteristics of the eighth transistor match characteristics of the pass gate transistor.
3. The driver circuit of claim 1 , wherein a width-to-length ratio of the second transistor is less than one, and wherein a width-to-length ratio of the third transistor is less than one.
4. The driver circuit of claim 3 , wherein the first, fifth, and sixth transistors comprise a low-resistance charging path from the supply voltage rail to the first output node, and wherein the first and second transistors comprise a high-resistance charging path from the supply voltage rail to the first output node.
5. The driver circuit of claim 1 , wherein the first, second, fifth, sixth, and seventh transistors comprise p-type metal oxide semiconductor field-effect transistors (MOSFETs), and wherein the third, fourth, and eighth transistors comprise n-type MOSFETs.
6. The driver circuit of claim 5 , wherein the first biasing voltage is configured to keep the second and sixth transistors turned on.
7. The driver circuit of claim 5 , wherein the second biasing voltage is configured to keep the third transistor turned on.
8. The driver circuit of claim 1 , further comprising:
a third inverter having an input coupled to the input node and an output;
a ninth transistor coupled between the supply voltage rail and the thirteenth current terminal and having a ninth control terminal coupled to the output of the third inverter; and
a tenth transistor coupled between the sixteenth current terminal and the second output node and having a tenth control terminal coupled to the output of the third inverter.
9. A circuit, comprising:
a first transistor coupled to a supply voltage rail and having a first control terminal coupled to an input node;
a second transistor coupled between the first transistor and a first output node, the second transistor having a second control terminal configured to receive a first biasing voltage;
a third transistor coupled to the first output node and having a third control terminal configured to receive a second biasing voltage;
a fourth transistor coupled between the third transistor and a second output node, the fourth transistor having a fourth control terminal coupled to the input node;
a fifth transistor coupled to the first and second transistors and having a fifth control terminal;
a sixth transistor coupled between the fifth transistor and the first output node, the sixth transistor having a sixth control terminal configured to receive the first biasing voltage;
a first inverter, comprising:
a seventh transistor coupled to the supply voltage rail and having a seventh control terminal coupled to the first output node; and
an eighth transistor coupled between the seventh transistor and the second output node, the eighth transistor having an eighth control terminal coupled to the first output node; and
a second inverter coupled to the seventh and eighth transistors and to the fifth control terminal.
10. The circuit of claim 9 , wherein the first output node is configured to be coupled to a control terminal of a pass gate transistor, and wherein characteristics of the eighth transistor match characteristics of the pass gate transistor.
11. The circuit of claim 10 , further comprising:
the pass gate transistor coupled between an input voltage and the second output node;
a capacitor coupled between the second output node and a ground node;
an analog-to-digital converter (ADC) having an input coupled to the second output node and an output; and
a digital filter circuit having an input coupled to the output of the ADC and an output coupled to the input node.
12. The circuit of claim 9 , wherein a width-to-length ratio of the second transistor is less than one, and wherein a width-to-length ratio of the third transistor is less than one.
13. The circuit of claim 12 , wherein the first, fifth, and sixth transistors comprise a low-resistance charging path from the supply voltage rail to the first output node, and wherein the first and second transistors comprise a high-resistance charging path from the supply voltage rail to the first output node.
14. The circuit of claim 9 , wherein the first, second, fifth, sixth, and seventh transistors comprise p-type metal oxide semiconductor field-effect transistors (MOSFETs), and wherein the third, fourth, and eighth transistors comprise n-type MOSFETs.
15. The circuit of claim 14 , wherein the first biasing voltage is configured to keep the second and sixth transistors turned on, and wherein the second biasing voltage is configured to keep the third transistor turned on.
16. The circuit of claim 9 , further comprising:
a third inverter having an input coupled to the input node and an output;
a ninth transistor coupled between the supply voltage rail and the seventh transistor, the ninth transistor having a ninth control terminal coupled to the output of the third inverter; and
a tenth transistor coupled between the eighth transistor and the second output node, the tenth transistor having a tenth control terminal coupled to the output of the third inverter.