Direct conversion FSK receiver using frequency tracking filters

• US 5,451,899 A
• Filed: 09/08/1994
• Issued: 09/19/1995
• Est. Priority Date: 09/14/1993
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Plessey Semiconductors Limited (Plessey Group Holdings Ltd.)
• Inventors: Lawton, Rodney J.
• Primary Examiner(s): GRIMM, SIEGFRIED H
• Application Number:
  US08/302,510
• Time in Patent Office: 376 Days
• Field of Search: 329/300, 329/301, 329/302, 329/303, 375/80, 375/82, 375/88, 375/102, 375/103, 375/120
• US Class Current: 329/302
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H03D 3/24 Modifications of demodulators to reject or remove amplitude variations by means of locked-in oscillator circuits
• CPC Class Codes: H04L 27/1525 using quadrature demodulation

Abstract

In a direct conversion receiver in which received radio frequency signals are mixed with quadrature local oscillator signals in I and Q channels, the output signals from the mixers are applied to a phase detector by way of respective frequency tracking filters to reduce the noise bandwidth and improve the sensitivity.

Claims

1. A direct conversion frequency shift keying radio receiver arrangement in which received radio frequency signals are mixed with local oscillator signals in quadrature-phase arms and the output signals from these quadrature-phase arms are applied to a phase detector to recover data signals represented by said frequency shift keying, wherein each of said quadrature-phase arms includes a frequency tracking filter.

3. A direct conversion radio receiver arrangement in accordance with claim 1 wherein the frequency tracking filters comprise injection locked oscillators.

4. A direct conversion radio receiver arrangement in accordance with claim 1 wherein the frequency tracking filters comprise phase locked loop circuits.

5. A direct conversion radio receiver arrangement in accordance with claim 1 wherein the frequency tracking filters comprise phase locked filter loops.

6. A direct conversion radio receiver arrangement in accordance with claim 3 wherein signals derived from said injection locked oscillators are utilized to derive a signal for controlling the frequency of said local oscillator signals.

2. A direct conversion radio receiver arrangement in which received radio frequency signals are applied to two mixer circuits to which local oscillator signals are applied in phase quadrature, wherein output signals from said mixer circuits are applied to a phase detector of the receiver arrangement by way of respective frequency tracking filter circuits.

7. A direct conversion radio receiver arrangement in accordance with claim 2 wherein the frequency tracking filters comprise injection locked oscillators.

8. A direct conversion radio receiver arrangement in accordance with claim 2 wherein the frequency tracking filters comprise phase locked loop circuits.

9. A direct conversion radio receiver arrangement in accordance with claim 2 wherein the frequency tracking filters comprise phase locked filter loops.

10. A direct conversion radio receiver arrangement in accordance with claim 7 wherein signals derived from said injection locked oscillators are utilized to derive a signal for controlling the frequency of said local oscillator signals.