Balance differential receiver

• US 5,815,020 A
• Filed: 09/24/1996
• Issued: 09/29/1998
• Est. Priority Date: 09/24/1996
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Yip, William Chunhung, Allen, Steven Peter
• Primary Examiner(s): Wells, Kenneth B.
• Application Number:
  US08/718,733
• Time in Patent Office: 735 Days
• Field of Search: 327/1-12, 327/254, 327/255, 327/407, 327/238, 327/99, 327/298
• US Class Current: 327/255
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

A quadrant detector circuit (400) has a comparator (442) having a pair of inputs (438, 440). A first (438) of the pair of inputs (438, 440) is coupled to an in-phase signal (434) and a second (440) of the pair of inputs (438, 440) is coupled to a quadrature phase signal (436). A sample counter (448) has a reset (446) coupled to an output (444) of the comparator (442). A controllable switch (456) has a selection input (454) coupled to an output (452) of the sample counter (448). The controllable switch (456) is capable of switching between a local oscillator signal (458) and an inverse local oscillator signal (460).

Claims

1. A balance differential receiver circuit, comprising:

quadrant detector means, operably coupled to a pair of inputs, a first of the pair of inputs coupled to an in-phase signal and a second of the pair of inputs coupled to a quadrature phase signal, for detecting a phase relationship between the in-phase signal and the quadrature signal; and

quadrant rotation means, having a selection input operably coupled to the quadrant detector means, for switching between a local oscillator signal and an inverse local oscillator signal.

2. The balance differential receiver circuit of claim 1, further comprising a sample counter having an input coupled to an output of the quadrant detector means.

3. The balance differential receiver circuit of claim 1, wherein the quadrant detector means comprises an in-phase differential amplifier and a quadrature phase differential amplifier.

4. The balance differential receiver circuit of claim 3, wherein the in-phase differential amplifier has a first input connected to a first polarity in-phase signal and a second input connected to a second polarity in-phase signal.

5. The balance differential receiver circuit of claim 3, wherein the quadrature phase differential amplifier has a first input connected to a first polarity quadrature signal and a second input connected to a second polarity quadrature phase signal.

6. The balance differential receiver circuit of claim 1, further including an amplifier, the amplifier comprising:

an in-phase differential operational amplifier having a positive input connected to a first polarity in-phase signal and a negative input connected to a second polarity in-phase signal;

a quadrature phase differential operational amplifier having a positive input connected to a first polarity quadrature phase signal and a negative input connected to a second polarity quadrature phase signal;

an in-phase single ended operational amplifier having a positive input connected to a negative output of the in-phase differential operational amplifier and a negative input connected to a positive output of the in-phase differential operational amplifier, the in-phase single ended operational amplifier having an output coupled to the quadrant detector means; and

a quadrature phase single ended operational amplifier having a positive input connected to a negative output of the quadrature phase differential operational amplifier and a negative input connected to a positive output of the quadrature phase differential operational amplifier, the quadrature phase single ended operational amplifier having an output coupled to the quadrant detector means.

7. The balance differential receiver circuit of claim 6, further including a resistor between the negative output of the in-phase differential operational amplifier and the negative output of the quadrature phase differential operational amplifier.

8. The balance differential receiver circuit of claim 1, wherein the quadrant detector means comprises an exclusive OR gate.

9. The balance differential receiver circuit of claim 2, wherein the sample counter comprises a D-flip flop.

10. The balance differential receiver circuit of claim 2, wherein the sample counter has an input coupled to the local oscillator signal.

11. A balance differential receiver circuit, comprising:

means for amplifying an in-phase signal and a quadrature phase signal to produce an amplified in-phase signal and an amplified quadrature phase signal;

means for comparing the amplified in-phase signal with the amplified quadrature phase signal, wherein the means for comparing is operative to transmit an indication signal when the amplified in-phase signal and the amplified quadrature phase signal have a common polarity; and

rotation means, operably coupled to the indication signal, for selecting between a first local oscillator signal and a second local oscillator signal, wherein the second local oscillator signal is an inverse of the first local oscillator signal.

12. The balance differential receiver circuit of claim 11, wherein the means for comparing comprises an exclusive OR gate having an output coupled to a sample counter.

13. The balance differential receiver circuit of claim 12, wherein the sample counter is operably coupled to the first local oscillator signal.

14. A method of extracting a data signal that includes an in-phase component and a quadrature phase component using a local oscillator signal, the method comprising the steps of:

(a) receiving the in-phase component from an in-phase mixer;

(b) receiving the quadrature phase component from a quadrature phase mixer;

(c) comparing the in-phase component to the quadrature phase component to form an indication signal; and

(d) selecting, responsive to the indication signal, between the local oscillator signal and an inverse of the local oscillator signal.