Oscillator with two outputs in quadrature

Abstract

An oscillator includes four identical cells each producing a phase shift of 90 degrees. The output signal from one cell is applied to the input of the next cell, and with the cells looping back to themselves. Each cell includes a current amplifier and a parallel inductance-capacitance resonant circuit configured such that the output current from one cell is a fraction of the capacitive current of the parallel resonant circuit. This causes the 90° phase shift between the input and output currents of each cell.

1. A quadrature oscillator comprising:
 four cells coupled together, each cell producing a phase shift of 90 degrees between an output current and an input current, the output current being applied as an input current to an adjacent cell, and an output of each cell looping back to its input a last cell looping back to an input of a first cell, each cell comprising  
 a current amplifier, and  
 a resonant circuit connected to said current amplifier such that the output current from each cell is substantially less than a capacitive current of said resonant circuit providing the 90° phase shift between the input and output currents.  
 
     
     
       2. A quadrature oscillator according to  claim 1 , wherein said resonant circuit comprises a parallel inductance-capacitance resonant circuit. 
     
     
       3. A quadrature oscillator according to  claim 1 , wherein said current amplifier comprises a transistor in a common-base configuration; and wherein said resonant circuit is connected to a collector of said transistor. 
     
     
       4. A quadrature oscillator according to  claim 1 , further comprising a capacitive element connected between adjacent cells. 
     
     
       5. A quadrature oscillator according to  claim 1 , further comprising an inductive element connected between adjacent cells. 
     
     
       6. A quadrature oscillator according to  claim 5 , wherein said inductive element comprises a transformer having a secondary winding defining said inductive element, and having a primary winding defining an inductive portion of said resonant circuit. 
     
     
       7. A quadrature oscillator comprising:
 four cells coupled together, each cell producing a phase shift of 90 degrees between an output current and an input current, the output current being applied as an input current to an adjacent cell, and an output of each cell looping back to its input a last cell looping back to an input of a first cell, each cell comprising  
 a transistor in a common-base configuration, and  
 a resonant circuit connected to a collector of said transistor such that the output current from each cell is substantially less than a capacitive current of said resonant circuit providing the 90° phase shift between the input and output currents.  
 
     
     
       8. A quadrature oscillator according to  claim 7 , wherein said resonant circuit comprises a parallel inductance-capacitance resonant circuit. 
     
     
       9. A quadrature oscillator according to  claim 7 , further comprising a capacitive element connected between adjacent cells. 
     
     
       10. A quadrature oscillator according to  claim 7 , further comprising an inductive element connected between adjacent cells. 
     
     
       11. A quadrature oscillator according to  claim 7 , wherein said inductive element comprises a transformer having a secondary winding defining said inductive element, and having a primary winding defining an inductive portion of said resonant circuit. 
     
     
       12. A quadrature oscillator comprising:
 four cells coupled together, each cell producing a phase shift of 90 degrees between an output current and an input current, the output current being applied as an input current to an adjacent cell, and an output of each cell looping back to its input a last cell looping back to an input of a first cell, each cell comprising  
 a current amplifier and a resonant circuit connected thereto.  
 
     
     
       13. A quadrature oscillator according to  claim 12 , wherein said current amplifier comprises a transistor in a common-base configuration; and wherein said resonant circuit is connected to a collector of said transistor. 
     
     
       14. A quadrature oscillator according to  claim 12 , wherein said resonant circuit has an output providing the 90° phase shift between the input and output currents; and wherein the output current from each ell is substantially less than a capacitive current of said resonant circuit. 
     
     
       15. A quadrative oscillator according to  claim 12 , wherein said resonant circuit comprises a parallel inductance-capacitance resonant circuit. 
     
     
       16. A quadrature oscillator according to  claim 12 , further comprising a capacitive element connected between adjacent cells. 
     
     
       17. A quadrature oscillator according to  claim 12 , further comprising an inductive element connected between adjacent cells. 
     
     
       18. A quadrature oscillator according to  claim 12 , wherein said inductive element comprises a transformer having a secondary winding defining said inductive element, and having a primary winding defining an inductive portion of said resonant circuit. 
     
     
       19. A method of making a quadrature oscillator comprising the steps of:
 coupling four cells together such that the output current of one cell is applied as the input current to an adjacent cell, and an output of each cell looping back to its input a last cell looping back to an input of a first cell, each cell comprising a current amplifier and is resonant circuit connected thereto such that the output current from each cell is substantially less than a capacitive current of the resonant circuit providing a 90° phase shift between the input and output currents.  
 
     
     
       20. A method according to  claim 19 , wherein said resonant circuit comprises a parallel inductance-capacitance resonant circuit. 
     
     
       21. A method according to  claim 19 , wherein said current amplifier comprises a transistor in a common-base configuration, and wherein the method further comprises the step of connecting the resonant circuit to a collector of the transistor. 
     
     
       22. A method according to  claim 19 , further comprising the step of connecting adjacent cells together using a capacitive element. 
     
     
       23. A method according to  claim 19 , further comprising the step of connecting adjacent cells together using an inductive element. 
     
     
       24. A method according to  claim 23 , wherein the inductive device comprises a transformer having a secondary winding defining the inductive element, and having a primary winding defining an inductive portion of the resonant circuit.