High-IF superheterodyne receiver incorporating high-Q complex band pass filter
A novel and useful reconfigurable superheterodyne receiver that employs a 3 rd order complex IQ charge-sharing band-pass filter (BPF) for image rejection and 1 st order feedback based RF BPF for channel selection filtering. The operating RF input frequency of the receiver is 500 MHz to 1.2 GHz with a varying high IF range of 33 to 80 MHz. The gain stages are inverter based g m stages and the total gain of the receiver is 35 dB and in-band IIP3 at mid gain is +10 dBm. The NF of the receiver is 6.7 dB which is acceptable for the receiver without an LNA. The architecture is highly reconfigurable and follows the technology scaling.
1. A superheterodyne radio frequency (RF) receiver, comprising:
an RF input node for receiving an RF input signal;
a local oscillator (LO) input node for receiving an LO signal;
a mixer coupled to said RF input node and said LO input node, said mixer operative to frequency translate said RF input signal in accordance with said LO signal, said mixer producing an in-phase/quadrature (I/Q) intermediate frequency (IF) signal of frequency substantially higher than a bandwidth of said RF input signal;
a band pass discrete-time (DT) IF filter coupled to said IF signal, wherein said band pass DT IF filter presents an input impedance that is substantially higher at higher frequency offsets from said IF frequency than at lower frequency offsets from said IF frequency.
2. The superheterodyne RF receiver according to claim 1 , wherein said band pass DT IF filter comprises a complex charge sharing filter operative to perform charge sharing between said I and said Q signals.
3. The superheterodyne RF receiver according to claim 2 , wherein said complex charge sharing filter has a bandwidth substantially at said IF frequency.
4. The superheterodyne RF receiver according to claim 2 , wherein said complex charge sharing filter operates at full sampling rate of said LO signal.
5. The superheterodyne RF receiver according to claim 2 , wherein said band pass DT IF filter comprises at least one additional complex charge sharing filter cascaded with said complex charge sharing filter.
6. The superheterodyne RF receiver according to claim 2 , wherein said band pass DT IF filter comprises a notch filter coupled to said complex charge sharing filter, wherein said notch filter output is coupled to said band pass DT IF filter input.
7. The superheterodyne RF receiver according to claim 1 , wherein said band pass DT IF filter comprises a notch filter, wherein said notch filter output is coupled to said band pass DT IF filter input.
8. The superheterodyne RF receiver according to claim 7 , wherein said notch filter comprises an N-path filter.
9. A superheterodyne radio frequency (RF) receiver, comprising:
an RF input node for receiving an RF input signal;
a local oscillator (LO) input node for receiving an LO signal;
a mixer coupled to said RF input node and said LO input node, said mixer operative to frequency translate said RF input signal in accordance with said LO signal, said mixer producing an in-phase/quadrature (I/Q) intermediate frequency (IF) signal of frequency substantially higher than a bandwidth of said RF input signal;
a discrete time (DT) band pass filter coupled to said IF signal and operative to filter out blocking interferer signals and image components of the desired signal;
a notch filter coupled to the output of said band pass filter and operative to reject wanted signals and pass all blocker and unwanted signals; and
a feedback loop operative to feedback the output of said notch filter to the input of said band pass filter.
10. The superheterodyne RF receiver according to claim 9 , wherein said band pass filter comprises a 3 rd order complex IQ charge sharing filter.
11. The superheterodyne RF receiver according to claim 9 , wherein said notch filter comprises a complex N-path notch filter.
12. The superheterodyne RF receiver according to claim 9 , wherein said band pass DT IF filter comprises a complex charge sharing filter operative to perform charge sharing between said I and said Q signals.
13. The superheterodyne RF receiver according to claim 12 , wherein said complex charge sharing filter has a bandwidth substantially at said IF frequency.
14. The superheterodyne RF receiver according to claim 12 , wherein said complex charge sharing filter operates at full sampling rate of said LO signal.
15. The superheterodyne RF receiver according to claim 12 , wherein said band pass DT IF filter comprises at least one additional complex charge sharing filter cascaded with said complex charge sharing filter.
16. A superheterodyne radio frequency (RF) receiver, comprising:
an RF input node for receiving an RF input signal;
a local oscillator (LO) input node for receiving an LO signal;
a mixer coupled to said RF input node and said LO input node, said mixer operative to frequency translate said RF input signal in accordance with said LO signal, said mixer producing an in-phase/quadrature (I/Q) intermediate frequency (IF) signal of frequency substantially higher than a bandwidth of said RF input signal;
a complex IQ charge sharing discrete time (DT) band pass filter centered at said IF coupled to said IF signal and operative to filter out blocking interferer signals and images of the desired signal;
a complex notch filter coupled to the output of said band pass filter and operative to reject wanted signals and pass all blocker and unwanted signals; and
a transconductance feedback path operative to feed the output of said notch filter back to the input of said band pass filter.
17. The superheterodyne RF receiver according to claim 16 , wherein said band pass filter comprises a 3 rd order complex IQ charge sharing filter.
18. The superheterodyne RF receiver according to claim 16 , wherein said notch filter comprises a complex N-path notch filter.
19. The superheterodyne RF receiver according to claim 16 , wherein said complex charge sharing filter operates at full sampling rate of said LO signal.
20. The superheterodyne RF receiver according to claim 16 , wherein said receiver comprises one or more gain stages.
21. The superheterodyne RF receiver according to claim 20 , wherein said gain stages comprise inverter-based g m stages.