Differential signal comparator

• US 20050266810A1
• Filed: 06/01/2004
• Published: 12/01/2005
• Est. Priority Date: 06/01/2004
• Status: Active Grant

• Current Assignee: ATI Technologies ULC (Advanced Micro Devices, Inc.)
• Original Assignee: ATI Technologies Incorporated (Advanced Micro Devices, Inc.)
• Inventors: Drapkin, Oleg, Temkine, Grigori
• Granted Patent: US 7,295,828 B2
• Time in Patent Office: Days
• US Class Current: 455/126
• CPC Class Codes: H03F 2200/78 A comparator being used in a controlling circuit of an amplifier
• CPC Class Codes: H03F 2203/45028 the differential amplifier amplifying transistors are folded cascode coupled transistors
• CPC Class Codes: H03F 3/45183 Long tailed pairs H03F3/4521, H03F3/45237 take precedence
• CPC Class Codes: H03F 3/45192 Folded cascode stages
• CPC Class Codes: H04L 25/0272 Arrangements for coupling to multiple lines, e.g. for differential transmission

Abstract

A differential signal comparator includes an input circuit operative to provide an absolute input current difference value that is associated with the absolute difference of differential input signal levels, and a reference circuit operative to provide an absolute reference current difference value that is associated with the absolute difference of the reference signal levels. Current comparison of the absolute input current difference value with the absolute reference current difference value identify whether an input differential signal is bigger than the reference noise level and should be processed, or an input differential signal is smaller than the reference noise level and should not be processed.

Claims

1. An apparatus for differential signal communications, the apparatus comprising:

an input circuit operative to receive a first input voltage and a second input voltage of differential input signal, the input circuit operative to generate an input absolute value of the difference between a first current associated with the first input voltage and a second current associated with the second input voltage;

a reference circuit operative to generate a reference absolute value of the difference between a first reference current associated with a first reference voltage and a second reference current associated with a second reference voltage; and

a current comparator operative to compare the input absolute value and the reference absolute value such that if the input absolute value is greater than the reference absolute value, an incoming signal is determined to be an incoming communication signal and if the input absolute value is smaller than the reference absolute value, the incoming signal is determined to be an incoming noise signal.

2. The apparatus of claim 1 wherein the first current is proportional to the absolute difference of the input differential signal levels.

3. The apparatus of claim 1 wherein the second current is proportional to the absolute difference of the reference differential signal levels.

4. The apparatus of claim 1 wherein the input circuit provides differential signals absolute difference calculations using a plurality of current mirror.

5. The apparatus of claim 1 wherein input circuit includes a differential input voltage to current converter and the reference circuit includes a differential reference voltage to current converter such that the differential input voltage to current converter is operative to provide a current that is related to the absolute input signal difference, and the differential reference voltage to current converter is operative to provide a complimentary current that is related to the absolute reference signal difference to the current comparator.

6. The apparatus of claim 1 further comprising:

a processing device operably coupled to the differential input signal and to the differential signal comparator such that the processing device is operative to generate a wake-up command if the incoming signal is determined to be an incoming communication signal.

7. An apparatus for differential signal communications, the apparatus comprising:

an input circuit operative to receive a first input voltage and the second input voltage of differential input signal, the input circuit operative to generate an input absolute value of the difference between a first current associated with the first input voltage and a second current associated with the second input voltage;

a reference circuit operative to generate a reference absolute value of the difference between a first reference current associated with a first reference voltage and a second reference current associated with a second reference voltage;

a comparator operative to compare the input absolute value and the reference absolute value such that if the input absolute value is greater than the reference absolute value, an incoming signal is determined to be an incoming communication signal and if the input absolute value is smaller than the reference absolute value, an incoming signal is determined to be an incoming noise signal; and

a processing device operative to generate a wake-up command and start processing data if the incoming signal is determined to be the incoming communication signal or to generate an idle signal and stop processing data if the incoming signal is determined to be the incoming noise.

10. The apparatus of claim 9 wherein the first current is proportional to the absolute difference of the input differential signal levels.

11. The apparatus of claim 9 wherein the second current is proportional to the absolute difference of the reference differential signal levels.

12. The apparatus of claim 9 wherein the input circuit provides differential signals absolute difference calculations based on current mirrors application.

13. The apparatus of claim 9 wherein input circuit includes a differential input voltage to current converter and the reference circuit includes a differential reference voltage to current converter such that the differential input voltage to current converter is operative to provide a current that is related to the absolute input signal difference, and the differential reference voltage to current converter is operative to provide a complimentary current that is related to the absolute reference signal difference to the current comparator.

14. A method for different signal comparison, the method comprising:

receiving a differential input signal;

generating a first current associated with the first input voltage level and the second current associated with the second input voltage level;

generating an absolute input current difference value based on the first current and the second current;

receiving a differential reference signal;

generating a first reference current associated with the first reference voltage level and the second reference current associated with the second reference voltage level;

generating an absolute reference current difference value based on the first reference current and the second reference current;

comparing the absolute input current difference value with the absolute reference current difference value; and

if the absolute input current difference value is greater than the absolute reference current difference value, activating a processing device to start processing data.

15. The method of claim 14 further comprising:

if the absolute input current difference value is smaller than the absolute reference current difference value, ignoring the input signal as noise to stop processing data.

16. The method of claim 14 wherein the absolute difference of the input current value is proportional to the absolute difference of the input differential signal levels.

17. The apparatus of claim 14 wherein the absolute difference of the reference current value is proportional to the absolute difference of the reference differential signal levels.