Quadrature envelope-sampling of intermediate frequency signal in receiver

• US 20020176522A1
• Filed: 05/25/2001
• Published: 11/28/2002
• Est. Priority Date: 05/25/2001
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Fan, Yiping
• Application Number:
  US09/865,236
• Publication Number:
  US 20020176522A1
• Time in Patent Office: Days
• US Class Current: 375/340
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 1/0014 using DSP [Digital Signal Processor] quadrature modulation and demodulation
• CPC Class Codes: H04B 1/0025 using a sampling rate lower than twice the highest frequency component of the sampled signal for demodulation of angle-modulated signals H03D3/006
• CPC Class Codes: H04B 1/0039 using DSP [Digital Signal Processor] quadrature modulation and demodulation
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04L 2027/0016 Stabilisation of local oscillators
• CPC Class Codes: H04L 2027/0024 at the receiver end
• CPC Class Codes: H04L 27/3881 using sampling and digital processing, not including digital systems which imitate heterodyne or homodyne demodulation

Abstract

An apparatus and method for the two-dimensional direct intermediate frequency sampling of a received signal. A receiver is equipped with a circuit for converting a received radio frequency signal to an intermediate frequency signal. The converted intermediate frequency signal is sampled by a pair of lowpass analog-to-digital converters. The sampling scheme involves quadrature envelope sampling of the intermediate frequency signal. The sampling scheme further involves sampling the Q-channel signal at a quarter of the intermediate frequency carrier period after the I-channel signal is sampled.

Claims

1. A receiver comprising:

a radio frequency mixer;

an intermediate frequency filter;

an amplifier;

a first lowpass analog-to-digital converter directly connected to said amplifier;

a second lowpass analog-to-digital converter directly connected to said amplifier; and

a digital signal processor connected to said first and second lowpass analog-to-digital converters.

2. The receiver according to claim 1 wherein said receiver forms a part of a communications device.

3. The receiver according to claim 2 wherein said communications device comprises a cellular phone.

4. The receiver according to claim 2 wherein said communications device comprises a wireless device.

5. The receiver according to claim 2 wherein said communications device comprises a code division multiple access (CDMA) device.

6. The receiver according to claim 2 wherein said communications device comprises a time division multiple access (TDMA) device.

7. The receiver according to claim 1 further comprising a radio frequency filter.

8. The receiver according to claim 7 wherein said radio frequency filter comprises a surface acoustic wave filter.

9. The receiver according to claim 1 wherein said intermediate frequency filter comprises a surface acoustic wave filter.

10. The receiver according to claim 1 wherein said amplifier comprises a variable gain amplifier.

11. The receiver according to claim 1 wherein said first and second lowpass analog-to-digital converters comprise Sigma Delta analog-to-digital converters.

12. The receiver according to claim 1 wherein said first lowpass analog-to-digital converter comprises a flash-type analog-to-digital converter.

14. The method according to claim 13 wherein said direct sampling comprises:

sampling a first channel at a predetermined time; and

sampling a second channel a quarter of the intermediate frequency carrier period after said sampling of said first channel.

15. The method according to claim 13 wherein said direct sampling is accomplished with a pair of lowpass analog-to-digital converters.

16. The method according to claim 15 wherein said lowpass analog-to-digital converters comprise Sigma Delta analog-to-digital converters.

17. The method according to claim 13 wherein said direct sampling is accomplished with a single flash-type lowpass analog-to-digital converter.

13. A method for direct sampling of an intermediate frequency signal in a receiver comprising:

receiving a signal;

converting said signal to an intermediate frequency signal;

filtering said intermediate frequency signal;

amplifying said filtered intermediate frequency signal;

directly sampling said amplified intermediate frequency signal; and

processing said directly sampled signal with a digital signal processor.