Radio transmission frequency digital signal generation

• US 20030210746A1
• Filed: 03/19/2003
• Published: 11/13/2003
• Est. Priority Date: 03/20/2002
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Asbeck, Peter M., Galton, Ian
• Granted Patent: US 7,953,174 B2
• Time in Patent Office: Days
• US Class Current: 375/247
• CPC Class Codes: H04B 14/06 using differential modulation, e.g. delta modulation

Abstract

The invention is directed to digital generation of RF signals. In the digital domain, digital RF signals are converted to the digital signals clocked at a high speed clock that is phase-synchronized with the RF carrier. A band-pass delta-sigma modulator produces a bit stream from the converted digital signals.

Claims

1. A method for digital generation of RF signals, the method comprising steps of:

timing adjusting digital RF signals produced by a digital circuit to a first frequency phase-synchronized to an RF transmission frequency;

up converting timing adjusted RF signals to a second frequency that is a multiple of the RF transmission frequency;

band-pass delta-sigma modulating the up converted RF signals to produce an output bit stream.

2. The method of claim 1, wherein the first frequency is an exact submultiple of the second frequency.

3. The method of claim 2, wherein the second frequency is four times the RF transmission frequency.

4. The method of claim 2, wherein the first frequency is higher than a bandwidth for transmission of the RF signals.

5. The method of claim 1, wherein said step of up converting is conducted according to the following equation:

y(n)=x_i(n)s₁(n)+x_q(n)s₂(n)

where s₁(n) is the signal {1,1,−

1,−

1, . . .} and s₂(n) is the signal {−

1,1,1,−

1 . . . }, x_i(n) is an in-phase component of the RF signal provided by said step of timing adjusting, and x_q(n) is a quadrature component of the RF signal provided by said step of timing adjusting.

6. The method of claim 1, wherein the RF transmission frequency comprises a baseband RF transmission frequency.

7. The method of claim 6, wherein the second frequency is four times the RF transmission frequency and the first frequency is an exact submultiple of the second frequency.

8. The method of claim 1, wherein said steps are carried out in a single integrated circuit.

9. The method of claim 1, wherein said steps are carried out in a CMOS integrated circuit.

10. The method of claim 1, further comprising steps of amplifying and filtering the RF signal resulting from said step of band-pass delta-sigma converting.

11. The method of claim 10, wherein said step of amplifying uses a switching amplifier and said step of filtering is conducted subsequent to said step of amplified.

12. The method of claim 11, further comprising a step of modulating power to the switching amplifier.

13. The method of claim 12, wherein said step of filtering removes undesired out of band spectral components and feeds back power associated with said undesired out of band spectral components back to said switching amplifier.

14. The method of claim 1, wherein the output stream produced by said step of band-pass delta-sigma modulating is a single bit output stream.

15. The method of claim 1, wherein the output stream produced by said step of band-pass delta-sigma modulating is a multiple bit output stream.

16. A method for digital generation of RF signals, comprising steps of:

bringing multi-bit digital representations of RF signals at an integrated circuit digital processing clock frequency up to a multiple of the RF transmission frequency; and

band-pass delta-sigma modulating, at the multiple of the RF transmission frequency, the digital representations of RF signals to produce an output bit stream including the analog content of the RF signals.

17. The method according to claim 16, wherein the multiple of the RF transmission frequency is four times a baseband frequency of RF transmission.

18. An integrated signal processing circuit for RF signal production, the circuit comprising:

a digital signal processor that produces digitally represented multi-bit in-phase and quadrature signals at a processing circuit clock frequency;

a digital signal processor that timing adjusts the multi-bit in-phase and quadrature signals to a first RF frequency;

an up converter that converts the multi-bit in-phase and quadrature signals to a second RF frequency; and

a band-pass delta-sigma modulator operating at the second frequency that produces an output bit stream representation of the multi-bit in-phase and quadrature signals.

19. A transmitter including the integrated circuit of claim 18, wherein the output bit steam is a single bit resolution bit stream, further comprising:

a switching power amplifier to amplify the single bit resolution bit stream; and

a filter to remove out of band components from the output of the switching power amplifier.