Single-chip software configurable transceiver for asymmetric communication system

• US 5,909,463 A
• Filed: 11/04/1996
• Issued: 06/01/1999
• Est. Priority Date: 11/04/1996
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: May, Michael R., Greaves, Carlos A., Rybicki, Mathew A., Johnson, Terence L., Pendleton, Matthew A., Molnar, Peter R., Porter, John M., Levin, Howard E., Gleason, Jeffrey P., Wiprud, Robin, Sudhaman, Sujit, Everett, Jody
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Maddox, Michael W.
• Application Number:
  US08/741,634
• Time in Patent Office: 939 Days
• Field of Search: 375/220, 375/219, 375/221, 375/222, 375/223, 370/276, 370/295, 370/296, 370/464, 370/480, 370/389, 370/395, 370/403, 370/404, 370/402, 370/400, 370/401, 455/73
• US Class Current: 375/220
• CPC Class Codes: H04L 27/0002 analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line duplex arrangements H04L5/143
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04Q 2213/13034 A/D conversion, code compression/expansion
• CPC Class Codes: H04Q 2213/1305 Software aspects
• CPC Class Codes: H04Q 2213/13103 Memory
• CPC Class Codes: H04Q 2213/1319 Amplifier, attenuation circuit, echo suppressor
• CPC Class Codes: H04Q 2213/13199 Modem, modulation
• CPC Class Codes: H04Q 2213/1332 Logic circuits

Abstract

A transceiver (5) for an asymmetric communication system such as asymmetric digital subscriber line (ADSL) includes a configuration register (71) defining operation at either a central office (CO) or a remote terminal (RT). The configuration register (71) includes a control bit (72) for selecting either CO or RT mode. The transceiver (5) includes a signal processing module (70) configured according to the state of the control bit (72). For example, a digital interface (70) converts transmit data into transmit symbols and converts received symbols into receive data. The digital interface (70) uses a large memory (158) as a buffer in the transmit path and a small memory (160) as a buffer in the receive path in CO mode. In RT mode, the digital interface (70) uses the small memory (160) in the transmit path and the large memory (158) in the receive path. The selective configuration allows a single integrated circuit to be used in both CO and RT equipment.

Claims

1. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a signal processor having a data input terminal for receiving a digital transmit signal, a data output terminal for providing a digital receive signal, an input terminal coupled to said receive port, and an output terminal coupled to said transmit port, said signal processor converting said digital transmit signal into a digital representation of an analog transmit signal having a frequency content, and converting a digital representation of an analog receive signal into said digital receive signal according to a frequency content of the digital representation of the analog receive signal;

said signal processor comprising;

control means for determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate; and

a digital interface having an input coupled to said control means and operable in first and second modes in response to said control means being in a first logic state or a second logic state, respectively, said digital interface converting said digital transmit signal into a plurality of transmit symbols at said first data rate, and converting a plurality of receive symbols received at said second data rate into said digital receive signal,

wherein said digital interface uses a first memory buffer for converting said digital transmit signal into said plurality of transmit symbols and uses a second memory buffer which is smaller than said first memory buffer for converting said plurality of receive symbols into said digital receive signal when said control means indicates said first logic state, and wherein said digital interface uses said second memory buffer for converting said digital transmit signal into said plurality of transmit symbols and uses said first memory buffer for converting said plurality of receive symbols into said digital receive signal when said control means indicates said second logic state,

wherein said transceiver is selectively operable at either end of said asymmetrical communication link.

35. The transceiver of claim 1 wherein said signal processor further comprises an analog front end module for converting the digital representation of the analog transmit signal into said analog transmit signal, and for converting said analog receive signal into the digital representation of the analog receive signal.

2. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a signal processor having a data input terminal for receiving a digital transmit signal, a data output terminal for providing a digital receive signal, an input terminal coupled to said receive port, and an output terminal coupled to said transmit port, said signal processor converting said digital transmit signal into a digital representation of an analog transmit signal having a frequency content, and converting a digital representation of an analog receive signal into said digital receive signal according to a frequency content of the digital representation of the analog receive signal;

said signal processor comprising;

control means for determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate; and

a circular echo synthesis (CES) module having an input coupled to said control means and operable in first and second modes in response to said control means being in a first logic state or a second logic state, respectively,

wherein said CES module interpolates a transmit signal representation based on the digital representation of the analog transmit signal to provide a cancellation signal when said control means indicates said first logic state, and which generates a second cancellation signal in response to said transmit signal representation and decimates said second cancellation signal to provide said cancellation signal when said control means indicates said second logic state, wherein said signal processor subtracts said cancellation signal from a receive signal representation based on the digital representation of the analog receive signal,

wherein said transceiver is selectively operable at either end of said asymmetrical communication link.

36. The transceiver of claim 2 wherein said signal processor further comprises an analog front end module for converting the digital representation of the analog transmit signal into said analog transmit signal, and for converting said analog receive signal into the digital representation of the analog receive signal.

3. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a signal processor having a data input terminal for receiving a digital transmit signal, a data output terminal for providing a digital receive signal, an input terminal coupled to said receive port, and an output terminal coupled to said transmit port, said signal processor converting said digital transmit signal into a digital representation of an analog transmit signal having a frequency content, and converting a digital representation of an analog receive signal into said digital receive signal according to a frequency content of the digital representation of the analog receive signal;

said signal processor comprising;

control means for determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate; and

a fast Fourier transform (FFT) module having an input coupled to said control means and operable in first and second modes in response to said control means being in a first logic state or a second logic state, respectively,

wherein said FFT module performs an inverse FFT on a first transmit signal representation based on the digital representation of the analog transmit signal to provide a second transmit signal representation based on the digital representation of the analog transmit signal when said control means indicates said first logic state, and which performs an FFT on a first receive signal representation based on the digital representation of the analog receive signal to provide a second receive signal representation based on the digital representation of the analog receive signal when said control means indicates said second logic state,

wherein said transceiver is selectively operable at either end of said asymmetrical communication link.

37. The transceiver of claim 3 wherein said signal processor further comprises an analog front end module for converting the digital representation of the analog transmit signal into said analog transmit signal, and for converting said analog receive signal into the digital representation of the analog receive signal.

4. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a signal processor having a data input terminal for receiving a digital transmit signal, a data output terminal for providing a digital receive signal, an input terminal coupled to said receive port, and an output terminal coupled to said transmit port, said signal processor converting said digital transmit signal into a digital representation of an analog transmit signal having a frequency content, and converting a digital representation of an analog receive signal into said digital receive signal according to a frequency content of the digital representation of the analog receive signal;

said signal processor comprising;

control means for determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate; and

a filter having an input coupled to said control means and operable in first and second modes in response to said control means being in a first logic state or a second logic state, respectively,

wherein when said control means indicates said first logic state said filter filters a first transmit signal representation based on the digital representation of the analog transmit signal to provide a second transmit signal representation based on the digital representation of the analog transmit signal, and wherein when control means indicates said second logic state said filter filters a first receive signal representation based on the digital representation of the analog transmit signal to provide a second transmit signal representation based on the digital representation of the analog transmit signal,

wherein said transceiver is selectively operable at either end of said asymmetrical communication link.

5. The transceiver of claim 4 wherein said filter comprises a digital finite impulse response (FIR) filter, wherein when said control means indicates the said first logic state said digital FIR filter operates with a first set of coefficients and wherein when said control means indicates the said second logic state said digital FIR filter operates with a second set of coefficients.

6. The transceiver of claim 5 wherein said second set of coefficients differs from said first set of coefficients.

7. The transceiver of claim 4 wherein said filter comprises a digital biquadratic filter, wherein when said control means indicates said first logic state said digital biquadratic filter operates with a first set of coefficients and wherein when said control means indicates said second logic state said digital biquadratic filter operates with a second set of coefficients.

8. The transceiver of claim 4 wherein said filter further comprises an analog filter, wherein when said control means indicates said first logic state said analog filter has a first pole-zero characteristic and wherein when said control means indicates said second logic state said analog filter has a second pole-zero characteristic.

38. The transceiver of claim 4 wherein said signal processor further comprises an analog front end module for converting the digital representation of the analog transmit signal into said analog transmit signal, and for converting said analog receive signal into the digital representation of the analog receive signal.

9. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a signal processor having a data input terminal for receiving a digital transmit signal, a data output terminal for providing a digital receive signal, an input terminal coupled to said receive port, and an output terminal coupled to said transmit port, said signal processor converting said digital transmit signal into a digital representation of an analog transmit signal having a frequency content, and converting a digital representation of an analog receive signal into said digital receive signal according to a frequency content of the digital representation of the analog receive signal;

said signal processor comprising;

control means for determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate;

an analog front end module having an input coupled to said control means and operable in first and second modes in response to said control means being in a first logic state or a second logic state, respectively, comprising;

an interpolator having an input for receiving a first transmit signal representation based on the digital representation of the analog transmit signal, and an output; and

an oversampled modulator having an input coupled to said output of said interpolator, and an output coupled to said transmit port,

wherein when said control means indicates said first logic state said interpolator has a first predetermined order and wherein when said control means indicates said second logic state said interpolator has a second predetermined order,

wherein said transceiver is selectively operable at either end of said asymmetrical communication link.

39. The transceiver of claim 9 wherein said analog front end module further converts said analog receive signal into the digital representation of the analog receive signal.

10. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a signal processor having a data input terminal for receiving a digital transmit signal, a data output terminal for providing a digital receive signal, an input terminal coupled to said receive port, and an output terminal coupled to said transmit port, said signal processor converting said digital transmit signal into an analog transmit signal having a frequency content, and converting an analog receive signal into said digital receive signal according to said frequency content of said analog receive signal;

said signal processor comprising;

control means for determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate; and

an analog front end module having an input coupled to said control means and operable in first and second modes in response to said control means being in a first logic state or a second logic state, respectively,

wherein said analog front end module comprises an oversampled analog-to-digital converter having an input coupled to said receive port, and an output for providing a representation of said analog receive signal, wherein when said control means indicates said second logic state said signal processor uses all of said oversampled analog-to-digital converter to convert said analog receive signal into said digital receive signal, and wherein when said control means indicates said first logic state said signal processor uses only a portion of said oversampled analog-to-digital converter to convert said analog receive signal into said digital receive signal,

wherein said transceiver is selectively operable at either end of said asymmetrical communication link.

11. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a data processor coupled to an internal bus for accessing memory locations via said internal bus in response to a program;

a plurality of peripheral modules coupled to said transmit port, said receive port, and said internal bus, wherein said data processor and said plurality of peripheral modules together process a digital transmit signal into a digital representation of an analog transmit signal having a frequency content, and process a digital representation of an analog receive signal into a digital receive signal; and

each of said plurality of peripheral modules coupled to a control means for determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate when in a first logic state, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate when in a second logic state.

12. The transceiver of claim 11 wherein a portion of the peripheral modules are hardware modules.

13. The transceiver of claim 11 wherein a portion of the peripheral modules are software modules.

14. The transceiver of claim 11 wherein said data processor includes a direct memory access (DMA) channel having a programmable direction.

15. The transceiver of claim 11 further comprising a program memory coupled to said data processor having a first portion for storing a first plurality of instructions for configuring at least one of said plurality of peripheral modules when said control means indicates the said first logic state and a second portion for storing a second plurality of instructions for configuring at least one of said plurality of peripheral modules when said control means indicates the said second logic state.

16. The transceiver of claim 15 wherein the program memory further comprises a third portion for storing a plurality of software modules, wherein said data processor executes said plurality of software modules to process said digital transmit signal and said digital representation of an analog transmit signal.

17. The transceiver of claim 13 wherein said first plurality of instructions includes a first instruction which causes said data processor to set a control bit of said control means of said at least one of said plurality of peripheral modules to said first logic state, and wherein said second plurality of instructions includes a second instruction which causes said data processor to set said control bit of said control means of said at least one of said plurality of peripheral modules to said second logic state.

18. The transceiver of claim 11 wherein said data processor is characterized as being a digital signal processor.

19. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

an internal bus;

a data processor coupled to said internal bus for accessing memory locations via said internal bus in response to a program;

a digital interface coupled to said internal bus which processes a digital transmit signal into a plurality of transmit symbols at said first data rate, and processes a plurality of receive symbols received at said second data rate into a digital receive signal;

a plurality of signal processing peripherals coupled to said internal bus, wherein said data processor in conjunction with said plurality of signal processing peripherals processes said plurality of transmit symbols into a digital representation of an analog transmit signal, and processes a digital representation of an analog receive signal into said plurality of receive symbols; and

control means for indicating whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate;

said control bit further determining a mode of operation of at least one said digital interface and said plurality of signal processing peripherals.

20. The transceiver of claim 19 wherein said data processor further comprising:

an analog front end module having an input terminal coupled to said receive port, an output coupled to said transmit port, and a bi-directional terminal coupled to said internal bus, wherein said analog front end module processes the digital representation of an analog transmit signal into an analog transmit signal, and processes an analog receive signal into the digital representation of the analog receive signal.

21. The transceiver of claim 19 wherein said data processor further comprises a host processor interface having a first bi-directional signal terminal adapted to be coupled to an external data processor, and a second bi-directional terminal coupled to said internal bus, wherein said host processor interface allows said external data processor to communicate with said data processor.

22. The transceiver of claim 19 further comprising a memory coupled to said data processor for storing said program.

23. The transceiver of claim 19 characterized as being implemented within a single integrated circuit.

24. The transceiver of claim 19 wherein said plurality of signal processing peripherals comprises a circular echo synthesis (CES) module, a fast Fourier transform (FFT) module, and a time domain equalizer.

25. The transceiver of claim 19 in which each of said plurality of signal processing peripherals having a control means for indicating whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate.

26. A transceiver for an asymmetric communication system, comprising:

a hardware portion for operating at a first data rate;

a software portion;

a data processor for executing the software portion to operate at a second data rate, wherein the second data rate is different the first data rate;

a control means for indicating when the transceiver is in one of a first state and a second state;

wherein, when the transceiver is in a first state, the hardware portion is in a data transmit path of the transceiver, and the software portion is in a data receive path of the transceiver; and

wherein, when the transceiver is in a second state, the hardware portion is in the data receive path of the transceiver, and the software portion is in the data transmit path of the transceiver.

27. The transceiver of claim 26, wherein the hardware portion and the software portion perform similar functions.

28. The transceiver of claim 27, wherein the hardware portion and the software portion perform filtering functions.

29. The transceiver of claim 27, wherein the software portion is stored in non-volatile memory.

30. The transceiver of claim 26, wherein the hardware portion performs a first function when in the data transmit path, and a second function when in the data receive path.

31. The transceiver of claim 30, wherein the first function and the second function are substantially different.

32. The transceiver of claim 31, wherein the first function is an inverse fast Fourier transform function and the second function is a fast Fourier transform function.

33. The transceiver of claim 30, wherein the first function and the second function are substantially similar.

34. The transceiver of claim 33, wherein the first function and the second function perform a filtering function.

40. A transceiver for an asymmetric communication system, comprising:

a transmit port adapted for coupling to an asymmetrical communication link, said transmit port transmitting data at a first data rate;

a receive port adapted for coupling to said asymmetrical communication link, said receive port receiving data at a second data rate;

a signal processor having a data input terminal for receiving a digital transmit signal, a data output terminal for providing a digital receive signal, an input terminal coupled to said receive port, and an output terminal coupled to said transmit port, said signal processor converting said digital transmit signal into a digital representation of an analog transmit signal having a frequency content, and converting a digital representation of an analog receive signal into said digital receive signal according to a frequency content of the digital representation of the analog receive signal;

said signal processor comprising;

a digital interface having a digital port for being coupled to an external data processor, and a register, wherein said digital interface alters a state of at least one control bit of said register in response to a command received from said external data processor via said digital port;

said at least one control bit determining whether said first data rate is a first predetermined data rate and said second data rate is a second predetermined data rate, or whether said first data rate is said second predetermined data rate and said second data rate is said first predetermined data rate; and

a signal processing module having an input coupled to said digital interface and operable in first and second modes in response to said at least one control bit being in a first logic state or a second logic state, respectively,

wherein said external data processor is capable of configuring said transceiver to operate at either end of said asymmetrical communication link.