Data extraction threshold circuit and method

• US 9,853,504 B2
• Filed: 09/30/2014
• Issued: 12/26/2017
• Est. Priority Date: 12/16/2013
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Neidorff, Robert A.
• Primary Examiner(s): Chang, Joseph
• Application Number:
  US14/501,850
• Publication Number:
  US 20150171634A1
• Time in Patent Office: 1,183 Days
• Field of Search: 307104
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H03K 19/20 characterised by logic function, e.g. AND, OR, NOR, NOT circuits H03K19/003 - H03K19/01 take precedence
• CPC Class Codes: H03K 2005/00078 Fixed delay
• CPC Class Codes: H03K 5/1532 Peak detectors measuring characteristics of individual pulses G01R29/02
• CPC Class Codes: H03K 5/1536 Zero-crossing detectors in measuring circuits G01R19/175
• CPC Class Codes: H03K 5/24 the characteristic being amplitude
• CPC Class Codes: H04B 5/0093 with one coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/02 using transceiver
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A circuit for setting a threshold level for extracting data from a signal stream includes a terminal couplable to the signal stream. A peak detector is coupled to the terminal. A valley detector is coupled to the terminal. A comparator is coupled to outputs of the peak detector and the valley detector for generating a threshold voltage for extracting data or commands from the signal stream. A method of extracting data from a signal stream including: peak detecting the signal stream to generate a first signal; valley detecting the signal stream to generate a second signal; combining the first and second signals to generate a threshold signal; and extracting data from the signal stream utilizing the threshold level signal.

Claims

1. A circuit extracting data from a signal stream comprising:

a data stream terminal for receiving the signal stream;

a peak detector having an input coupled to the data stream terminal and an output;

a valley detector having an input coupled to the data stream terminal and an output coupled to the output of the peak detector at a node;

a pre-amplifier having an input coupled to the node, an input connected to the data stream terminal, and an output; and

a data comparator having a first input connected to the node, a second input connected to the output of the pre-amplifier, and a data output.

2. The circuit of claim 1 including:

a first RC circuit coupled to the output of the peak detector and the node; and

a second RC circuit coupled to the output of the valley detector and the node.

3. The circuit of claim 1 including:

a first capacitor coupled between the output of the peak detector and ground and a first resistor coupled between the output of the peak detector and the node; and

a second capacitor coupled between the output of the peak detector and ground and a second resistor coupled between the output of the peak detector and the node, wherein a signal at the node is a threshold level signal.

4. The circuit of claim 1 in which:

the peak detector is a first low value resistor having a first end connected to the data stream terminal and a second end, and including a first diode and a first high value resistor connected in series between the a second end and the node, and a first capacitor connected to between the first diode and first high value resistor and a ground; and

the valley detector is a second low value resistor having a third end connected to the data stream terminal and a fourth end, and including a second diode and a second high value resistor connected in series between the fourth end and the node, and a second capacitor connected to between the second diode and second high value resistor and the ground.

5. The circuit of claim 1 in which:

the peak detector is a first comparator having a first input connected to the data stream terminal, a peak output, and a second input coupled to the peak output, and including a first diode and a first resistor connected in series between the a peak output and the node, and a first capacitor connected to between the first diode and first resistor and a ground; and

the valley detector is a second comparator having a third input connected to the data stream terminal, a valley output, and a fourth input coupled to the valley output, and including a second diode and a second resistor connected in series between the valley output and the node, and a second capacitor connected to between the second diode and second resistor and the ground.

6. A method of extracting data from a signal stream comprising:

peak detecting the signal stream to generate a first signal;

valley detecting the signal stream to generate a second signal;

combining the first and second signals to generate a threshold signal;

receiving the signal stream at a first input terminal of a preamplifier;

coupling a second input terminal of the preamplifier to the threshold signal; and

comparing the output of the preamplifier to the threshold signal to extract data from the signal stream.

7. The method of claim 6 including:

coupling a first RC filter to the first signal and a node;

coupling a second RC filter to the second signal and the node; and

combining the first and second signals at the node to generate the threshold level signal.

8. In a primary side wireless power transmitter for being inductively coupled to a secondary side wireless power receiver for supplying power to the wireless power receiver to power a load coupled to the wireless power receiver, a primary side controller receiving communications from the secondary side wireless power receiver through the inductive coupling, comprising:

a peak detector receiving a signal stream from the secondary side wireless power receiver and having a peak output coupled to a node;

a valley detector receiving a signal stream from the secondary side wireless power receiver and having a valley output coupled to the node;

a pre-amplifier having an input coupled to the node, an input connected to the signal stream, and an output; and

a comparator having a first input coupled to the node, a second input coupled to the output of the pre-amplifier, and a data output.

9. The controller of claim 8 including:

a first RC circuit coupled to the peak output of the peak detector; and

a second RC circuit coupled to the valley output of the valley detector.

10. The controller of claim 8 in which:

the peak detector is a first low value resistor having a first end connected to the signal stream and a second end, and including a first diode and a first high value resistor connected in series between the a second end and the node, and a first capacitor connected to between the first diode and first high value resistor and a ground; and

the valley detector is a second low value resistor having a third end connected to the signal stream and a fourth end, and including a second diode and a second high value resistor connected in series between the fourth end and the node, and a second capacitor connected to between the second diode and second high value resistor and the ground.

11. The controller of claim 8 in which:

the peak detector is a first comparator having a first input connected to the signal stream, the peak output, and a second input coupled to the peak output, and including a first diode and a first resistor connected in series between the a peak output and the node, and a first capacitor connected to between the first diode and first resistor and a ground; and

the valley detector is a second comparator having a third input connected to the signal stream, the valley output, and a fourth input coupled to the valley output, and including a second diode and a second resistor connected in series between the valley output and the node, and a second capacitor connected to between the second diode and second resistor and the ground.

12. A method of operating a primary side wireless power transmitter inductively coupled to a secondary side wireless power receiver for supplying power to the wireless power receiver to power a load coupled to the receiver comprising:

peak detecting a signal stream from the wireless power receiver to generate a first signal;

valley detecting the signal stream to generate a second signal;

generating a threshold voltage signal from the first and second signals;

receiving the signal stream at a first terminal of a preamplifier;

coupling a second terminal of the preamplifier to the threshold voltage signal; and

comparing the output of the preamplifier to the threshold signal to extract data from the signal stream.

13. The method of claim 12 including:

coupling a first RC filter to the first signal and a node;

coupling a second RC filter to the second signal and the node; and

combining the first and second signals at the node to generate the threshold level signal.