Apparatuses and methods for conversion of radio frequency (RF) signals to intermediate frequency (IF) signals
View Patent ↗Various embodiments implement apparatuses and methods for conversion of radio frequency (RF) signals to intermediate frequency (IF) signals. More particularly, some embodiments are directed toward down conversion of RF signals to IF signals in a multi-band radio receiver, such as a satellite receiver, using a single oscillator for different frequency bands. For example, some of the apparatuses and methods presented are suitable for integration into monolithic RF integrated circuits in low-cost satellite receivers for home entertainment use.
1. An apparatus for conversion of radio frequency (RF) signals in a plurality of frequency bands to intermediate frequency (IF) signals, comprising:
an oscillator capable of generating an oscillator frequency LO;
a first down conversion chain, comprising:
a first first-stage mixer coupled to the oscillator and configured to down convert a first received RF signal RF 1 using the oscillator frequency LO to generate a first first-stage IF signal IF a ,
a first frequency divider coupled to the oscillator and configured to generate a first divided oscillation frequency by dividing the oscillator frequency LO by a fraction P, and
a first second-stage mixer coupled to the first frequency divider and configured to down convert the first first-stage IF signal IF a using the second divided oscillation frequency to generate a first second-stage IF signal IF 1 ; and
a second down conversion chain, comprising:
a second first-stage mixer coupled to the oscillator and configured to down convert a second received RF signal RF 2 using the oscillator frequency LO, to generate a second first-stage IF signal IF b ,
a second frequency divider coupled to the oscillator and configured to generate a second divided oscillation frequency by dividing the oscillator frequency LO by a fraction Q, where P is different from Q, and
a second second-stage mixer coupled to the second frequency divider and configured to down convert the second first-stage IF signal IF b using the second divided oscillation frequency to generate a second second-stage IF signal IF 2 .
2. The apparatus of claim 1 , wherein the first received RF signal RF 1 is from a first frequency band and the second received RF signal RF 2 is from a second frequency band.
3. The apparatus of claim 1 , further comprising a first first-stage filter coupled between the first first-stage mixer and the first second-stage mixer and configured to filter the first first-stage IF signal IF a received by the first second-stage mixer.
4. The apparatus of claim 1 , further comprising a second first-stage filter coupled between the second first-stage mixer and the second second-stage mixer and configured to filter the second first-stage IF signal IFb received by the second second-stage mixer.
5. The apparatus of claim 1 , wherein the first second-stage IF signal IF, and the second second-stage IF signal IF 2 are within substantially the same frequency band (IF 1 -IF 2 ).
6. The apparatus of claim 5 , wherein the first frequency divider is configured to generate the first divided oscillation frequency by dividing the oscillator frequency LO by the fraction P, and the second frequency divider is configured to generate a second divided oscillation frequency by dividing the oscillator frequency LO by the fraction Q, and P, Q, and LO are selected such that |LO/P−|LO−RF 1 ∥≅|LO/Q−LO−RF 2 ∥≅IF 1 ≅IF 2 .
7. A method of converting radio frequency (RF) signals in a plurality of frequency bands to intermediate frequency (IF) signals in a multi-band receiver, comprising:
providing an oscillator frequency LO using an oscillator;
down converting a received RF signal RF using the oscillator frequency LO to generate a set of first-stage IF signals IF 1P ;
dividing the oscillator frequency by a plurality of different predetermined numbers to generate a plurality of divided oscillation frequencies; and
down converting the plurality of first-stage IF signals IF 1P using the plurality of divided oscillation frequencies to generate a plurality of second-stage IF signals IF 2P , respectively.
8. The method of claim 7 , wherein the plurality of first-stage IF signals IF 1P and the plurality of second-stage IF signals IF 2P are within substantially the same frequency band.
9. The method of claim 7 , wherein the received RF signal RF is from a first frequency band.
10. A method, comprising:
in an apparatus for converting radio frequency (RF) signals in a plurality of frequency bands to intermediate frequency (IF) signals:
receiving a frequency value RFreq corresponding to an input RF signal RF for a receiver;
receiving a set of frequencies values IFreq={IFreq 1 , IFreq 2 , . . . IFreq i } such that IFreq 1 ≅IFreq 2 ≅ . . . ≅IFreq i , wherein the frequency value IFreq i respectively corresponds to an output IF signal IF i in a set of output IF signals IF={IF 1 , IF 2 , . . . IF i } for the receiver, and the frequency values in the set of frequency values IFreq are within substantially the same frequency band;
determining an oscillator frequency LO and a set of different divisors D={D 1 , D 2 , D 3 , . . . D i }, such that |LO/D 1 −|LO−RF∥≅|LO/D 2 −|LO−RF∥≅ . . . ≅|LO/D 1 −|LO−RF∥≅IFreq 1 ≅IFreq 2 ≅ . . . ≅IFreq i , wherein the fraction value D 1 respectively corresponds to a frequency divider in a set of frequency dividers Div={Div 1 , Div 2 , . . . Div i } included in the receiver;
providing an oscillator for the receiver configured to generate the oscillator frequency LO;
providing a first-stage mixer for the receiver configured to down convert the input RF signal RF using the oscillator frequency LO to generate a first-stage IF signal IF a ,
providing the set of frequency dividers Div for the receiver, wherein frequency divider Div i is configured to generate a divided oscillation frequency DLO i in a set of divided oscillation frequencies DLO={DLO 1 , DLO 2 , DLO 3 , DLO i } by dividing the oscillator frequency LO by the fraction D i , and
providing a set of second-stage mixers Mix={Mix 1 , Mix 2 , Mix i } for the receiver, wherein second-stage mixer Mix, is configured to down convert the first-stage IF signal IF a using divided oscillation frequency DLO 1 in the set of divided oscillation frequencies DLO to generate the output IF signal IF i .