Method and system for down-converting an electromagnetic signal

• US 9,350,591 B2
• Filed: 03/05/2015
• Issued: 05/24/2016
• Est. Priority Date: 10/21/1998
• Status: Expired due to Fees

• Current Assignee: ParkerVision, Inc.
• Original Assignee: ParkerVision, Inc.
• Inventors: Sorrells, David F., Bultman, Michael J., Cook, Robert W., Looke, Richard C., Moses, Charley D., Rawlins, Gregory S., Rawlins, Michael W.
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US14/639,296
• Publication Number:
  US 20150244551A1
• Time in Patent Office: 446 Days
• Field of Search: 375/268, 375/279, 375/316, 375/318, 375/320, 375/324, 375/328, 375/329, 375/330, 375/340, 329/304, 329/306, 329345-347, 329/358, 329/361, 455/205, 455/210, 455/334, 455/341
• US Class Current: 1/1
• CPC Class Codes: H03C 1/62 Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present H03C1/28 - H03C1/34, H03C1/46, H03C1/48 take precedence
• CPC Class Codes: H03D 7/00 Transference of modulation from one carrier to another, e.g. frequency-changing H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F
• CPC Class Codes: H03D 7/1441 using field-effect transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/1475 Subharmonic mixer arrangements
• 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 1/16 Circuits
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 25/08 Modifications for reducing interference; Modifications for reducing effects due to line faults ; Receiver end arrangements for detecting or overcoming line faults
• CPC Class Codes: H04L 27/00 Modulated-carrier systems
• CPC Class Codes: H04L 27/06 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/14 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 27/148 using filters, including PLL-type filters
• CPC Class Codes: H04L 27/156 with demodulation using temporal properties of the received signal, e.g. detecting pulse width
• CPC Class Codes: H04L 27/2672 Frequency domain
• CPC Class Codes: H04L 27/3881 using sampling and digital processing, not including digital systems which imitate heterodyne or homodyne demodulation

Abstract

Methods for down converting a modulated carrier signal to a demodulated baseband signal are described herein. The method requires that a first portion of energy is transferred from the modulated carrier signal, and stored at a first storage device when a first switch is on. At least some of the energy stored in the first storage device is discharged when the first switch is off. The method further comprises transferring a second portion of energy from the modulated carrier signal, storing at a second storage device the second portion of transferred energy when a second switch is on, and discharging at least some of the energy stored in the second storage device when the second switch is off. A down-converted in-phase baseband signal portion is generated from the energy accumulated in the first storage device while both the charging and the discharging occurs, and a down-converted inverted in-phase baseband signal portion is generated from the energy accumulated in the second storage device while both the charging and the discharging occurs, and the two portions are combined with a first differential amplifier circuit to form a down-converted differential in-phase baseband signal.

Claims

1. A method for frequency down-converting a modulated carrier signal to a demodulated baseband signal, comprising:

transferring to an output of a first switch a first portion of energy from the modulated carrier signal during a sampling aperture with a specified frequency of a first control signal that controls when the first switch is on and when the first switch is off;

storing at a first storage device the first portion of transferred energy from the modulated carrier signal output by the first switch when the first switch is on, the first storage device having previously accumulated energy from the modulated carrier signal as a first accumulation of energy, the first portion of energy being added to the first accumulation of energy to result in a second accumulation of energy, discharging at least some of the second accumulation of energy when the first switch is off so as to leave a third accumulation of energy which results from an undischarged portion of the second accumulation of energy at the first storage device, and outputting a down-converted in-phase baseband signal portion of said modulated carrier signal derived from the energy stored at the first storage device while the storing and the discharging occurs;

transferring to an output of a second switch a second portion of energy from the modulated carrier signal during a sampling aperture with a specified frequency of a second control signal that controls when the second switch is on and when the second switch is off;

storing at a second storage device the second portion of transferred energy from the modulated carrier signal output by the second switch when the second switch is on, the second storage device having previously accumulated energy from the modulated carrier signal as a fourth accumulation of energy, the second portion of energy being added to the fourth accumulation of energy to result in a fifth accumulation of energy, discharging at least some of the fifth accumulation of energy when the second switch is off so as to leave a sixth accumulation of energy stored at the second storage device, and outputting a down-converted inverted in-phase baseband signal portion of said modulated carrier signal derived from the energy stored at the second storage device while the storing and the discharging occurs;

wherein said down-converted in-phase baseband signal portion is generated from both said second accumulation of energy and said third accumulation of energy;

wherein said down-converted inverted in-phase baseband signal portion is generated from both said fifth accumulation of energy and said sixth accumulation of energy; and

combining with a first differential amplifier circuit said down-converted in-phase baseband signal portion with said down-converted inverted in-phase baseband signal portion and outputting to a channel a down-converted differential in-phase baseband signal based on said down-converted in-phase baseband signal portion and said down-converted inverted in-phase baseband signal portion.

2. The method of claim 1, wherein said modulated carrier signal includes an amplitude variation.

3. The method of claim 1, wherein said modulated carrier signal includes a phase variation.

4. The method of claim 1, wherein said modulated carrier signal includes a combination of amplitude variation and phase variation.

5. The method of claim 1, wherein the sampling aperture of the first control signal transfers energy for at least one-tenth of a cycle of the modulated carrier signal and no more than one-half cycle of the modulated carrier signal.

6. The method of claim 1, wherein the sampling aperture of the second control signal transfers energy for approximately one-tenth of a cycle of the modulated carrier signal.

7. The method of claim 1, wherein the sampling apertures of the first and second control signals are defined by a windowing function u(t)−

u(t−

T_A), where a length of a windowing function aperture is T_A, which is at least one-tenth of a cycle of the modulated carrier signal and no more than a half cycle of the modulated carrier signal.

8. The method of claim 1, wherein for each respective first and second storage device, the energy discharged during any given discharge cycle is not completely discharged, with the remaining undischarged energy from the given discharge cycle becoming an initial condition for a next charging cycle that begins immediately following the given discharge cycle.

9. The method of claim 1, wherein each said first and second control signal operates at an aliasing rate selected so that energy of the modulated carrier signal is sampled and differentially applied to the respective first and second storage device at the frequency of the respective first and second control signal'"'"'s aperture.

10. The method of claim 1, further comprising:

filtering with a first filter said down-converted in-phase baseband signal portion; and

filtering with a second filter said down-converted inverted in-phase baseband signal portion.

11. The method of claim 10, wherein the first and second filters each comprise a low-pass filter.

12. The method of claim 1, wherein said first and second storage devices are capacitive storage circuits.

13. The method of claim 1, further comprising:

transferring to an output of a third switch a third portion of energy from the modulated carrier signal during a sampling aperture with a specified frequency of a third control signal that controls when the third switch is on and when the third switch is off;

storing at a third storage device the third portion of transferred energy from the modulated carrier signal output by the third switch when the third switch is on, the third storage device having previously accumulated energy from the modulated carrier signal as a seventh accumulation of energy, the third portion of energy being added to the seventh accumulation of energy to result in an eighth accumulation of energy, discharging at least some of the eighth accumulation of energy when the third switch is off so as to leave a ninth accumulation of energy which results from an undischarged portion of the eight accumulation of energy at the third storage device, and outputting a down-converted quadrature-phase baseband signal portion of said modulated carrier signal derived from the energy stored at the third storage device while the storing and the discharging occurs;

transferring to an output of a fourth switch a fourth portion of energy from the modulated carrier signal during a sampling aperture with a specified frequency of a fourth control signal that controls when the fourth switch is on and when the fourth switch is off;

storing at a fourth storage device the fourth portion of transferred energy from the modulated carrier signal output by the fourth switch when the fourth switch is on, the fourth storage device having previously accumulated energy from the modulated carrier signal as a tenth accumulation of energy, the fourth portion of energy being added to the tenth accumulation of energy to result in an eleventh accumulation of energy, discharging at least some of the eleventh accumulation of energy when the fourth switch is off so as to leave a twelfth accumulation of energy stored at the fourth storage device, and outputting a down-converted inverted quadrature-phase baseband signal portion of said modulated carrier signal derived from the energy stored at the fourth storage device while the storing and the discharging occurs;

wherein said down-converted quadrature-phase baseband signal portion is generated from both said eighth accumulation of energy and said ninth accumulation of energy;

wherein said down-converted inverted quadrature-phase baseband signal portion is generated from both said eleventh accumulation of energy and said twelfth accumulation of energy; and

combining at a second differential amplifier said down-converted quadrature-phase baseband signal portion with said down-converted inverted quadrature-phase baseband signal portion and outputting for another channel a down-converted differential quadrature-phase baseband signal based on said down-converted quadrature-phase baseband signal portion and said down-converted inverted quadrature-phase baseband signal portion.

14. The method of claim 13, wherein said modulated carrier signal includes an amplitude variation.

15. The method of claim 13, wherein said modulated carrier signal includes a phase variation.

16. The method of claim 13, wherein said modulated carrier signal includes a combination of amplitude variation and phase variation.

17. The method of claim 13, wherein the sampling aperture of the third control signal transfers energy for at least one-tenth of a cycle of the modulated carrier signal and no more than a half cycle of the modulated carrier signal.

18. The method of claim 13, wherein the sampling aperture of the fourth control signal transfers energy for approximately one-tenth of a cycle of the modulated carrier signal.

19. The method of claim 13, wherein the sampling apertures of the third and fourth control signals are defined by a windowing function u(t)−

u(t−

T_A), where a length of a windowing function aperture is T_A, which is at least one-tenth of a cycle of the modulated carrier signal and no more than a half cycle of the modulated carrier signal.

20. The method of claim 13, wherein for each respective third and fourth storage device, the energy discharged during any given discharge cycle is not completely discharged, with the remaining undischarged energy from the given discharge cycle becoming an initial condition for a next charging cycle that begins immediately following the given discharge cycle.

21. The method of claim 13, wherein each said third and fourth control signal operates at an aliasing rate selected so that energy of the modulated carrier signal is sampled and differentially applied to the respective third and fourth storage device at the frequency of the respective third and fourth control signal'"'"'s aperture.

22. The method of claim 13, further comprising:

filtering at a first filter said down-converted in-phase baseband signal portion;

filtering at a second filter said down-converted inverted in-phase baseband signal portion;

filtering at a third filter said down-converted quadrature-phase baseband signal portion; and

filtering at a fourth filter said down-converted inverted quadrature-phase baseband signal portion.

23. The method of claim 22, wherein the first, second, third, and fourth filters each comprise a low-pass filter.

24. The method of claim 13, wherein said first, second, third and fourth storage devices are capacitive storage circuits.