Low voltage swing pad driver and receiver

• US 20030137440A1
• Filed: 07/16/2002
• Published: 07/24/2003
• Est. Priority Date: 01/24/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Ranganathan, Sumant, Kwan, Tom W.
• Granted Patent: US 6,801,577 B2
• Time in Patent Office: Days
• US Class Current: 341/155
• CPC Class Codes: H04L 27/0002 analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line duplex arrangements H04L5/143

Abstract

Low voltage swing pad driver and receiver. A transmitter portion and a receiver portion are implemented within various devices that communicate using low voltage swing pads communicatively coupled via a trace. The transmitter portion of one device generates a current signal that is pushed/pulled to a low voltage swing pad and is then passed across the trace to another low voltage swing pad. The transmitter portion includes a current driver that outputs the current signal to the low voltage swing pads, and the receiver portion includes a trans-impedance amplifier that transforms the received current signal into a voltage signal. The low voltage swing pad driver and receiver generates a relatively low voltage swing when compared to CMOS full-scale voltage swings thereby significantly reducing the possibility of introducing any noise and/or distortion of data that is communicated via the interface.

Claims

1. A semiconductor system employing low swing pads, the semiconductor system comprising:

an integrated asynchronous digital subscriber line semiconductor chip; and

wherein the integrated asynchronous digital subscriber line semiconductor chip comprises an analog front-end portion;

the analog front-end portion comprises a transmitter portion and a receiver portion, the transmitter portion being communicatively coupled to a transmitter pad and the receiver portion being communicatively coupled to a receiver pad;

the transmitter portion comprises a voltage to current converter that is operable to convert a voltage signal to a current signal and to push/pull the current signal to the transmitter pad; and

the receiver portion comprises a current to voltage converter that is operable to receive a current signal at the receiver pad and to transform the received current signal to a voltage signal.

2. The semiconductor system of claim 1, wherein at least one of the current signal generated by the voltage to current converter of the transmitter and the current signal received by the current to voltage converter of the receiver portion comprises a voltage swing less than approximately plus or minus 100 milli-Volts.

3. The semiconductor system of claim 1, wherein the receiver portion comprises a digital level converter that is operable to convert the voltage signal from a first level to a second level.

4. The semiconductor system of claim 3, wherein the first level comprises a voltage of approximately 3.3 V and the second level comprises a voltage of approximately 1.8 V.

5. The semiconductor system of claim 1, wherein the receiver portion comprises a trans-impedance amplifier that is operable to receive the current signal and to transform the received current signal to the voltage signal.

6. The semiconductor system of claim 5, wherein the voltage signal comprises a voltage having a magnitude that is approximately 3.3 Volts.

7. The semiconductor system of claim 6, wherein the trans-impedance amplifier comprises a feedback resistor having a resistance that is substantially 1.2 kilo-Ohms.

8. The semiconductor system of claim 1, wherein the integrated asynchronous digital subscriber line semiconductor chip further comprises a scrambler and a digital level converter;

the scrambler receives a digital input signal and then generates a scrambled digital input signal; and

the digital level converter converts a level of the scrambled digital input signal and provides the level converted scrambled digital input signal to the transmitter portion.

9. The semiconductor system of claim 1, wherein the integrated asynchronous digital subscriber line semiconductor chip further comprises a de-scrambler and a digital level converter;

the receiver portion provides the digital signal to the digital level converter;

the digital level converter receives the digital signal and changes a level of the digital signal; and

the de-scrambler receives the voltage level changed digital signal and then generates a de-scrambled digital output signal.

10. The semiconductor system of claim 1, wherein at least one of the receiver pad and the transmitter pad communicatively couples to another device via a trace.

11. A low swing pad system, comprising:

a device comprising a transmitter pad and a receiver pad;

the device comprises a current signal transmitter that is operable to push/pull a current signal to the transmitter pad, the current signal comprising a voltage swing less than approximately plus or minus 100 milli-Volts; and

the device comprises a current signal receiver that is operable to receive a current signal comprising a voltage swing less than approximately plus or minus 100 milli-Volts.

12. The low swing pad system of claim 11, further comprising at least one additional device comprising at least one additional transmitter pad and at least one additional receiver pad;

and

wherein the transmitter pad and the at least one additional receiver pad are communicatively coupled via a trace;

the at least one additional transmitter pad and the receiver pad are communicatively coupled via at least one additional trace;

the at least one additional device comprises at least one additional current signal transmitter that is operable to push/pull at least one additional current signal to the at least one additional transmitter pad, the current signal comprising a voltage swing less than approximately plus or minus 100 milli-Volts; and

the at least one additional device comprises at least one additional current signal receiver that is operable to receive at least one additional current signal comprising a voltage swing less than approximately plus or minus 100 milli-Volts.

13. The low swing pad system of claim 11, wherein the current signal receiver comprises a trans-impedance amplifier is operable to receive the current signal and to transform the received current signal to the voltage signal.

14. The low swing pad system of claim 13, wherein the voltage signal comprises a voltage having a magnitude that is substantially 3.3 Volts.

15. The low swing pad system of claim 13, wherein the trans-impedance amplifier comprises a feedback resistor having a resistance that is substantially 1.2 kilo-Ohms.

16. The low swing pad system of claim 13, wherein the current signal receiver further comprises a swinging/inverting comparator that is operable to generate a single bit digital output signal from the voltage signal.

17. The low swing pad system of claim 11, wherein the device comprises an integrated asynchronous digital subscriber line semiconductor chip;

the integrated asynchronous digital subscriber line semiconductor chip comprises an analog front-end portion; and

the analog front-end portion comprises the current signal transmitter and the current signal receiver.

18. The low swing pad system of claim 11, wherein the device further comprises a scrambler and a digital level converter;

the scrambler receives a digital input signal and then generates a scrambled digital input signal;

the digital level converter converts a level of the scrambled digital input signal and provides the level converted scrambled digital input signal to the current signal transmitter; and

the current signal transmitter transforms the level converted scrambled digital input signal into the current signal.

19. The low swing pad system of claim 11, wherein the device comprises a de-scrambler and digital level converter;

the current signal receiver transforms the received current signal into a voltage signal;

the current signal receiver provides the voltage signal to the digital level converter;

the digital level converter receives changes a level of the voltage signal; and

the de-scrambler receives the level changed voltage signal and then generates a de-scrambled digital output signal.

20. The low swing pad system of claim 11, wherein at least one of the receiver pad and the transmitter pad communicatively couples to another device via a trace.

21. A low swing pad operating method, comprising:

transforming a voltage signal into a current signal;

pushing/pulling the current signal to a transmitter pad;

transmitting the current signal from the transmitter pad to a receiver pad via a trace;

receiving the current signal at the receiver pad; and

transforming the received current signal into a voltage signal; and

wherein the current signal comprises a voltage swing less than approximately plus or minus 100 milli-Volts.

22. The method of claim 21, wherein the method is performed within an analog front-end;

and

the analog front-end is contained within an integrated asynchronous digital subscriber line semiconductor chip.

23. The method of claim 22, wherein the analog front-end further comprises a transmitter portion and a receiver portion.

24. The method of claim 23, further comprising:

receiving a digital input signal;

scrambling the digital input signal;

changing a level of the scrambled digital input signal using a digital level converter; and

providing the level changed scrambled digital input signal to the transmitter portion.

25. The method of claim 23, further comprising:

providing the received the voltage signal to a digital level converter;

changing a level of the voltage signal using the digital level converter;

de-scrambling the level changed digital signal to generate a de-scrambled digital output signal.

26. A low swing pad operating method, comprising:

receiving a digital input signal;

scrambling the digital input signal;

converting a level of the digital input signal;

transforming the digital input signal into a current signal;

pushing/pulling the current signal to a transmitter pad;

transmitting the current signal from the transmitter pad to a receiver pad via a trace;

receiving the current signal at the receiver pad;

transforming the received current signal into a voltage signal;

converting a level of the voltage signal; and

de-scrambling the level converted voltage signal to generate a de-scrambled digital output signal.

27. The method of claim 26, wherein the current signal comprises a voltage swing less than approximately plus or minus 100 milli-Volts.

28. The method of claim 26, wherein the method is performed within an analog front-end;

and

the analog front-end is contained within an integrated asynchronous digital subscriber line semiconductor chip.

29. The method of claim 28, wherein the analog front-end further comprises a transmitter portion and a receiver portion.

30. The method of claim 26, wherein the transforming of the received current signal into the voltage signal is performed using a trans-impedance amplifier;

the converting the received voltage signal to a digital signal is performed using a swinging/inverting comparator.

31. An analog front-end receiver system, comprising:

a receive programmable gain amplifier that receives an analog input signal and is operable to selectively amplify the analog input signal;

a sigma-delta analog to digital converter that receives the analog input signal and converts the analog input signal into a digital input signal;

a digital level translator that modifies a voltage level of the digital input signal from a first voltage level to a second voltage level;

an analog front-end digital block that receives the digital input signal having the second voltage level; and

a low swing pad interface, communicatively coupled to the analog front-end digital block, that is operable to communicatively couple the digital input signal having the second voltage level to an external device; and

wherein the low swing pad interface comprises a voltage to current converter that is operable to convert the digital input signal having the second voltage level to a current signal that comprises a voltage swing less than approximately plus or minus 100 milli-Volts.

32. The analog front-end receiver system of claim 31, wherein the analog front-end receiver system is contained within an integrated asynchronous digital subscriber line semiconductor chip.

33. The analog front-end receiver system of claim 31, wherein the first voltage level comprises a voltage of approximately 3.3 V and the second voltage level comprises a voltage of approximately 1.8 V.

34. An analog front-end system, comprising:

a receive programmable gain amplifier that receives an analog input signal and is operable to selectively amplify the analog input signal;

a sigma-delta analog to digital converter that receives the analog input signal and converts the analog input signal into a digital input signal;

a digital level translator that modifies a voltage level of the digital input signal from a higher voltage level to a lower voltage level;

an analog front-end digital block that receives the digital input signal having the lower voltage level;

a low swing pad interface, communicatively coupled to the analog front-end digital block, that is operable to communicatively couple the digital input signal having the lower voltage level to an external device, the low swing pad interface is operable to receive a digital input signal and to communicatively couple the digital input signal to the analog front-end digital block;

at least one additional digital level translator that is operable to receive the digital input signal from the analog front-end digital block and to modifies a voltage level of a digital input signal received from the analog front-end digital block from the lower voltage level to the higher voltage level;

a sigma-delta digital to analog converter that receives the digital input signal having the high voltage level to an analog output signal;

a transmit programmable gain amplifier that receives an analog output signal and is operable to selectively amplify the analog output signal; and

wherein the low swing pad interface comprises a voltage to current converter that is operable to convert the digital input signal having the lower voltage level to a current signal that comprises a voltage swing less than approximately plus or minus 100 milli-Volts.

35. The analog front-end system of claim 34, wherein the analog front-end system is contained within an integrated asynchronous digital subscriber line semiconductor chip.

36. The analog front-end system of claim 34, wherein the higher voltage level comprises a voltage of approximately 3.3 V and the lower voltage level comprises a voltage of approximately 1.8 V.