Hybrid marchand/back-wave balun and double balanced mixer using same

1. A hybrid Marchand/back-wave balun comprising:

a first pair of coupled sections having a first primary section and first secondary section;

a second pair of coupled sections having a second primary section and second secondary section;

a first reactance interconnecting said first and second primary sections and a second reactance interconnecting said first and second secondary sections;

one of said reactances being open at high frequency and shorted at low frequency, the other reactance being shorted at high frequency and open at low frequency for selectively providing low frequency Marchand/high frequency back-wave function and high frequency Marchand/low frequency back-wave function.

2. The hybrid Marchand/back-wave balun of claim 1 in which said first reactance is an inductive reactance said second reactance is a capacitive reactance and said balun functions as a Marchand balun at low frequency and a back-wave balun at high frequency.

3. The hybrid Marchand/back-wave balun of claim 1 in which said first reactance is a capacitive reactance said second reactance is an inductive reactance and said balun functions as a Marchand balun at high frequency and a back-wave balun at low frequency.

4. The hybrid Marchand/back-wave balun of claim 2 further including a grounding capacitive reactance connected between said first and second primary sections and ground.

5. The hybrid Marchand/back-wave balun of claim 4 in which said grounding capacitive reactance includes first and second capacitances connected from each end of said inductive reactance to ground and a third capacitance connected from the free end of said second primary section to ground and said free end of said first primary section being connected to the single port of the balun.

6. The hybrid Marchand/back-wave balun of claim 2 further including a grounding inductive reactance connected from said first and second secondary sections to ground.

7. The hybrid Marchand/back-wave balun of claim 6 in which said grounding inductive reactance includes first and second inductances connected from one end of each secondary section to ground, the other ends of said secondary sections being the balanced balun ports.

8. The hybrid Marchand/back-wave balun of claim 3 further including a grounding inductive reactance connected between said first and second primary sections and ground.

9. The hybrid Marchand/back-wave balun of claim 8 in which said grounding inductive reactance includes first and second inductances connected from each end of said capacitive reactance to ground and a third inductance connected from said the free end of said second primary section to ground and said free end of said first primary section being connected to the single port of the balun.

10. The hybrid Marchand/back-wave balun of claim 3 further including a grounding capacitive reactance connected from said first and second secondary sections to ground.

11. The hybrid Marchand/back-wave balun of claim 10 in which said grounding capacitive reactance includes first and second capacitances connected from one end of each secondary section to ground, the other ends of said secondary sections being the balanced balun ports.

12. The hybrid Marchand/back-wave balun of claim 1 in which said balun is a distributed balun and said coupled sections are transmission line sections.

13. The hybrid Marchand/back-wave balun of claim 1 in which said balun is a lumped balun and said coupled sections are transformer sections.

14. The hybrid Marchand/back-wave balun of claim 1 in which one of said first and second reactances is a capacitive reactance and the other is an inductive reactance and they are implemented by parasitic capacitance and parasitic inductance of the coupled sections, respectively.

15. The hybrid Marchand/back-wave balun of claim 4 in which the grounding capacitive reactance is implemented by the parasitic capacitance of coupled sections.

16. The hybrid Marchand/back-wave balun of claim 6 in which the grounding inductive reactance is implemented by the parasitic inductance of the coupled sections.

17. A hybrid Marchand/back-wave balun comprising:

a first pair of coupled sections having a first primary section and first secondary section;

a second pair of coupled sections having a second primary section and second secondary section;

a first inductive reactance interconnecting to an IF port of said first and second secondary sections and a second inductive reactance interconnecting said first and second primary sections;

said first and second inductive reactances being open at high frequency and shorted at low frequency, for selectively providing low frequency Marchand function and high frequency back-wave function and an accessible IF port.

18. The hybrid Marchand/back-wave balun of claim 17 further including a first grounding capacitive reactance connected between said first inductive reactance of the first and second secondary sections and ground.

19. The hybrid Marchand/back-wave balun of claim 18 in which said first grounding capacitive reactance includes first and second capacitances connected from ground to the IF port and the end of said first inductive reactance of the first and second secondary sections.

20. The hybrid Marchand/back-wave balun of claim 19 further including a second capacitive reactance connected from said first and second primary sections to ground.

21. The hybrid Marchand/back-wave balun of claim 20 in which said second grounding capacitive reactance includes first and second capacitances connected from each end of said second inductive reactance to ground and a third capacitance connected from said the free end of said second primary section to ground.

22. A double balanced mixer with hybrid Marchand/back-wave baluns comprising:

a first hybrid Marchand/back-wave balun for receiving a first single input and providing a first balanced output;

a second hybrid Marchand/back-wave balun for receiving a second single input and providing a second balanced output; and

a balanced mixer core responsive to said first and second balanced outputs to provide a mixed signal from said first and second single inputs;

each of said hybrid Marchand/back-wave balun including

a first pair of coupled sections having a first primary section and first secondary section;

a second pair of coupled sections having a second primary section and second secondary section;

a first reactance interconnecting said first and second primary sections and a second reactance interconnecting said first and second secondary sections;

one of said reactances being open at high frequency and shorted at low frequency, the other reactance being shorted at high frequency and open at low frequency for selectively providing low frequency Marchand/high frequency back-wave function and high frequency Marchand/low frequency back-wave function.

23. The double balanced mixer with hybrid Marchand/back-wave baluns of claim 22 further including an impedance transforming network interconnected between said balun mixer core and said balanced outputs of each of said hybrid baluns.

24. The double balanced mixer with hybrid Marchand/back-wave baluns of claim 22 in which said first reactance is an inductive reactance, said second reactance is a capacitive reactance and said balun functions as a Marchand balun at low frequency and a back-wave balun at high frequency.

25. The double balanced mixer with hybrid Marchand/back-wave baluns of claim 22 in which said first reactance is a capacitive reactance, said second reactance is an inductive reactance and said balun functions as a Marchand balun at high frequency and a back-wave balun at low frequency.

26. The double balanced mixer with hybrid Marchand/back-wave baluns of claim 22 in which one of the first and second reactances are capacitive reactances and the other is an inductive reactances and they are implemented by parasitic capacitance and parasitic inductance of the coupled sections, respectively.