Chopped intermediate frequency wireless receiver
View Patent ↗A chopped intermediate frequency (IF) wireless receiver is disclosed. The wireless receiver includes a local oscillator (LO), a first and a second mixers, an LO frequency control module, an IF filter, a digital down converter and a down conversion controller. The LO provides a local oscillating signal to the first and second mixers. The first and second mixers converts a received radio frequency signal to an in-phase IF signal and a quadrature IF signal, respectively. The LO frequency control module alternately down converts a channel frequency by changing an oscillation frequency of the LO. Coupled to the digital down converter, the down conversion controller adjusts a complex sine wave within the digital down converter while the in-phase IF signal and the quadrature IF signal are being down-converted by the digital down converter to a baseband signal.
1. A radio frequency (RF) receiver comprising:
a local oscillator (LO) for generating a local oscillation signal;
first and a second mixers coupled to said LO, for converting a received RF signal to an in-phase intermediate frequency (IF) signal and a quadrature IF signal, respectively;
an LO frequency control module, coupled to said LO, for alternately down-converting a channel frequency on a frame-by-frame basis by changing an oscillation frequency of said LO via
even frame: f RFLO =f CH −f IF
odd frame: f RFLO =f CH +f IF
wherein f RFLO =said local oscillation frequency
f CH =said channel frequency
f IF =said IF signal frequency
a down converter, coupled to said first and second mixers, for down converting said in-phase IF signal and said quadrature IF signal to a baseband; and
a complex sinusoid signal IFLO, coupled to said down converter, for providing a complex sinusoid signal to said down converter; and
a down conversion controller, coupled to said complex sinusoid signal IFLO, for adjusting a complex sine wave within said down converter via said complex sinusoid signal IFLO.
2. The RF receiver of claim 1 , wherein said down conversion controller adjusts a complex sine wave e ±jωt within said down converter by
even frame: IFLO( t )= e −jω IF t
odd frame: IFLO( t )= e +jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
3. The RF receiver of claim 2 , wherein said frames are time-division multiple access (TDMA) frames.
4. The RF receiver of claim 1 , wherein said down conversion controller adjusts a complex sine wave e ±jωt within said down converter by
even frame: IFLO( t )= e +jω IF t
odd frame: IFLO( t )= e −jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
5. The RF receiver of claim 4 , wherein said frames are time-division multiple access (TDMA) frames.
6. The RF receiver of claim 1 , wherein said LO frequency control module alternately down-converts a channel frequency by
even frame: f RFLO =f CH +f IF
odd frame: f RFLO =f CH −f IF
wherein f RFLO =said local oscillation frequency
f CH =said channel frequency
f IF =said IF signal frequency.
7. The RF receiver of claim 6 , wherein said down conversion controller adjusts a complex sine wave e ±jωt within said down converter by
even frame: IFLO( t )= e +jω IF t
odd frame: IFLO( t )= e −jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
8. The RF receiver of claim 7 , wherein said frames are time-division multiple access (TDMA) frames.
9. The RF receiver of claim 6 , wherein said down conversion controller adjusts a complex sine wave e ±jωt within said down converter by
even frame: IFLO( t )= e −jω IF t
odd frame: IFLO( t )= e +jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
10. The RF receiver of claim 9 , wherein said frames are time-division multiple access (TDMA) frames.
11. The RF receiver of claim 1 , wherein said RF receiver further includes an IF filter.
12. The RF receiver of claim 1 , wherein said RF receiver further includes an analog-to-digital converter.
13. A method for enhancing signal quality within a radio frequency (RF) receiver, said method comprising:
receiving a RF signal;
alternately down-converting a channel frequency by changing a local oscillation frequency, wherein said local oscillation frequency is utilized for converting said received RF signal to an in-phase intermediate frequency (IF) signal and a quadrature IF signal, wherein said alternately down-converting further includes alternately down-converting said in-phase IF signal and said quadrature If signal on a frame-by-frame basis by
even frame: f RFLO =f CH −f IF
old frame: f RFLO =f CH +f IF
wherein f RFLO =said local oscillation frequency
f CH =said channel frequency
f IF =said IF signal frequency;
providing a complex sine for down converting said in-phase IF signal and said quadrature IF signal; and
adjusting said complex sine wave for down converting said in-phase IF signal and said quadrature IF signal to a baseband signal.
14. The method of claim 13 , wherein said adjusting further includes adjusting a complex sine wave e ±jωt by
even frame: IFLO( t )= e −jω IF t
odd frame: IFLO( t )= e +jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
15. The method of claim 14 , wherein said frames are time-division multiple access (TDMA) frames.
16. The method of claim 13 , wherein said adjusting further includes adjusting a complex sine wave e ±jωt by
even frame: IFLO( t )= e +jω IF t
odd frame: IFLO( t )= e −jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
17. The method of claim 16 , wherein said frames are time-division multiple access (TDMA) frames.
18. The method of claim 13 , wherein said alternately down-converting is performed by
even frame: f RFLO =f CH +f IF
odd frame: f RFLO =f CH −f IF
wherein f RFLO =said local oscillation frequency
f CH =said channel frequency
f IF =said IF signal frequency.
19. The method of claim 18 , wherein said adjusting further includes adjusting a complex sine wave e ±jωt by
even frame: IFLO( t )= e +jω IF t
odd frame: IFLO( t )= e −jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
20. The method of claim 19 , wherein said frames are time-division multiple access (TDMA) frames.
21. The method of claim 18 , wherein said adjusting further includes adjusting a complex sine wave e ±jωt by
even frame: IFLO( t )= e −jω IF t
odd frame: IFLO( t )= e +jω IF t
where e −jω IF t =Cos ω IF t−j Sin ω IF t
e +jω IF t =Cos ω IF t+j Sin ω IF t
ω IF =2πf IF .
22. The method of claim 21 , wherein said frames are time-division multiple access (TDMA) frames.