Line driver with separate pre-driver for feed-through capacitance

Patent metadata

Field	Value
Publication number	US-9344081-B2
Application number	US-201314123037-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 15, 2013
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

Embodiments of the invention are generally directed to a line driver with separate pre-driver for feed-through capacitance. An embodiment of an apparatus includes a differential pair of transistors to generate an output signal on a first output node and a second output node; a pass-through capacitance coupled with the first output node and the second output node; a first pre-driver to drive an input signal for the differential transistors; and a second pre-driver to drive the input signal for the pass-through capacitance.

First claim

What is claimed is:

1. An apparatus comprising:
a differential pair of transistors to generate an output signal on a first output node and a second output node, the differential pair including a first transistor including an output terminal coupled with the first output node and a second transistor including an output terminal coupled with the second output node;
a first pass-through capacitor having a first terminal coupled with the second output node;
a second pass-through capacitor having a first terminal coupled with the first output node;
a first pre-driver configured to drive an input signal for the differential pair of transistors, the first pre-driver including a first input to receive a first signal component of a differential input signal and a second input to receive a second signal component of the differential input signal, and including a first output coupled with an input terminal of the first transistor and a second output coupled with an input terminal of the second transistor; and
a second pre-driver including a first output and a second output, the first output of the second pre-driver coupled to a second terminal of the first pass-through capacitor, the second output of the second pre-driver coupled to a second terminal of the second pass-through capacitor, the second pre-driver further including a first input to receive the first signal component and a second input to receive the second signal component.

2. The apparatus of claim 1 , further comprising a third pass-through capacitor coupled between the first input of the second pre-driver and the second output of the second pre-driver, and a fourth pass-through capacitor coupled between the second input of the second pre-driver and the first output of the second pre-driver.

3. The apparatus of claim 1 , wherein the first and second pass-through capacitors are part of the second pre-driver.

4. The apparatus of claim 1 , further comprising a delay mechanism to delay the input signal to the first and second inputs of the second pre-driver by a time delay.

5. The apparatus of claim 4 , wherein the time delay is an amount of time that is sufficient for a voltage of a component of the input signal to reach a midpoint in a transition between signal values.

6. The apparatus of claim 4 , wherein the delay mechanism provides a first time delay for a rising edge signal and a second time delay for a falling edge signal.

7. The apparatus of claim 6 , wherein the first time delay and the second time delay are different values.

8. A method comprising:
receiving a first signal component of a differential input signal at a first input of a first pre-driver;
receiving a second signal component of the differential input signal at a second input of the first pre-driver;
driving a signal for a differential pair of transistors with a first pre-driver based on the first signal component and the second signal component by providing a first output to an input terminal of the first transistor and a second output to an input terminal of the second transistor;
receiving the first signal component of the differential input signal at a first input of a second pre-driver;
receiving the second signal component of the differential input signal at a second input of the second pre-driver;
driving an input signal for a first pass-through capacitor with the second pre-driver based on the first signal component and the second signal component of the differential input signal;
driving an input signal for a second pass-through capacitor with the second pre-driver based on the first signal component and the second signal component of the differential input signal; and
generating an output signal on a first output node and a second output node by providing the first output and the second output to control the differential pair of transistors and adjusting voltage levels at the first and second output nodes by the first and second pass-through capacitors.

9. The method of claim 8 , further comprising:
coupling the first input of the second pre-driver to the second input of the second pre-driver via a third pass-through capacitor; and
coupling the second input of the second pre-driver to the first input of the second pre-driver via a fourth pass-through capacitor.

10. The method of claim 8 , wherein the first and second pass-through capacitors are part of the second pre-driver.

11. The method of claim 8 , further comprising delaying the input signal to the first and second inputs of the second pre-driver by a time delay.

12. The method of claim 11 , wherein the time delay is an amount of time that is sufficient for a voltage of a component of the input signal to reach a midpoint in a transition between signal values.

13. The method of claim 11 , wherein delaying the input signal includes providing a first time delay for a rising edge signal and a second time delay for a falling edge signal.

14. The method of claim 13 , wherein the first time delay and the second time delay are different values.

15. A non-transitory computer readable storage medium comprising a digital representation of a feed-through line driver, the feed-through line driver comprising:
a differential pair of transistors to generate an output signal on a first output node and a second output node, the differential pair including a first transistor including an output terminal coupled with the first output node and a second transistor including an output terminal coupled with the second output node;
a first pass-through capacitor having a first terminal coupled with the second output node;
a second pass-through capacitor having a first terminal coupled with the first output node and the second output node;
a first pre-driver configured to drive an input signal for the differential pair of transistors, the first pre-driver including a first input to receive a first signal component of a differential input signal and a second input to receive a second signal component of the differential input signal, and including a first output coupled with an input terminal of the first transistor and a second output coupled with an input terminal of the second transistor; and
a second pre-driver including a first output and a second output, the first output of the second pre-driver coupled to a second terminal of the first pass-through capacitor, the second output of the second pre-driver coupled to a second terminal of the second pass-through capacitor, the second pre-driver further including a first input to receive the first signal component and a second input to receive the second signal component.

16. The non-transitory computer readable storage medium system of claim 15 , further comprising a third pass-through capacitor coupled between the first input of the second pre-driver and the second output of the second pre-driver, and a fourth pass-through capacitor coupled between the second input of the second pre-driver and the first output of the second pre-driver.

17. The non-transitory computer readable storage medium of claim 15 , wherein the first and second pass-through capacitors are part of the second pre-driver.

18. The non-transitory computer readable storage medium of claim 15 , wherein the feed-through line driver further comprises a delay mechanism to delay the input signal to the first and second inputs of the second pre-driver by a time delay.

Assignees

• Lattice Semiconductor Corp

Inventors

• Luo Kexin
• Chu Fangqing
• Yang Huaizhou
• Shen Yu
• Lee Inyeol

Classifications

• H03K17/56 Primary

  by the use, as active elements, of semiconductor devices (using diodes H03K17/74) · CPC title

• H04L25/0272

  Arrangements for coupling to multiple lines, e.g. for differential transmission · CPC title