Microwave semiconductor variable attenuation circuit

Abstract

A circuit for the variable attenuation of microwave signals including at least a first coupler and a first series circuit of inductors. Each inductor has a defined inductance, and one end of the first series circuit is connected to a first terminal of the first coupler. Also included is a second series circuit of inductors, each inductor having a defined inductance, where one end of the second series circuit is connected to a second terminal of the first coupler. A plurality of controllable resistance mechanisms, each being connected to a junction point between two respective inductors of the first or second series circuit are also included. The other end of the first series circuit is grounded through a first termination resistor and the other end of the second series circuit is grounded through a second termination resistor.

What is claimed is:  
     
         1 . A circuit for the variable attenuation of microwave signals comprising: 
 (a) at least a first coupler,    (b) a first series circuit of inductors, each inductor having a defined inductance, where one end of said first series circuit is connected to a first terminal of said first coupler,    (c) a second series circuit of inductors, each inductor having a defined inductance, where one end of said second series circuit is connected to a second terminal of said first coupler, and    (d) a plurality of means having controllable resistance, each of said means respectively being connected to a junction point between two respective inductors of said first or second series circuit.    
     
     
         2 . A circuit according to  claim 1 , characterized in that a second coupler is provided, where the other end of said first series circuit is connected to a first terminal of said second coupler, and the other end of said second series circuit is connected to a second terminal of said second coupler.  
     
     
         3 . A circuit according to  claim 2 , characterized in that inductors at the ends of said first and second series circuits have a predetermined inductance represented as L, the remaining inductors have an inductance 2L, and said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         4 . A circuit according to claims  2 , characterized in that each series circuit contains two inductors of equal inductance represented as L.  
     
     
         5 . A circuit according to  claim 4 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         6 . A circuit according to  claim 2 , characterized in that said second coupler has an impedance equal to the impedance of said first coupler.  
     
     
         7 . A circuit according to  claim 6 , characterized in that, said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         8 . A circuit according to claims  6 , characterized in that each series circuit contains two inductors of equal inductance represented as L.  
     
     
         9 . A circuit according to  claim 8 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         10 . A circuit according to  claim 2 , wherein said means having controllable resistance is a field-effect-transistor.  
     
     
         11 . A circuit according to  claim 10 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         12 . A circuit according to claims  10 , characterized in that each series circuit contains two inductors of equal inductance represented as L.  
     
     
         13 . A circuit according to  claim 12 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         14 . A circuit according to  claim 2 , characterized in that the means having controllable resistance is a diode.  
     
     
         15 . A circuit according to  claim 14 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         16 . A circuit according to claims  14 , characterized in that, each series circuit contains two inductors of equal inductance represented as L.  
     
     
         17 . A circuit according to  claim 16 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         18 . A circuit according to  claim 1 , characterized in that the other end of said first series circuit is grounded through a first termination resistor, and the other end of said second series circuit is grounded through a second termination resistor.  
     
     
         19 . A circuit according to  claim 18 , characterized in that inductors at the ends of said first and second series circuits have a predetermined inductance represented as L, the remaining inductors have an inductance 2L, and said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         20 . A circuit according to claims  18 , characterized in that each series circuit contains two inductors of equal inductance represented as L.  
     
     
         21 . A circuit according to  claim 20 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         22 . A circuit according to  claim 18 , wherein said means having controllable resistance is a field-effect-transistor.  
     
     
         23 . A circuit according to  claim 22 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         24 . A circuit according to claims  22 , characterized in that each series circuit contains two inductors of equal inductance represented as L.  
     
     
         25 . A circuit according to  claim 24 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         26 . A circuit according to  claim 18 , characterized in that the means having controllable resistance is a diode.  
     
     
         27 . A circuit according to  claim 26 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         28 . A circuit according to claims  26 , characterized in that each series circuit contains two inductors of equal inductance represented as L.  
     
     
         29 . A circuit according to  claim 28 , characterized in that said first and second series circuits satisfy Z 0   2 =2L/C, where the characteristic impedance of said first coupler is represented as Z 0 , and the capacity of said means having controllable resistance is represented as C.  
     
     
         30 . A circuit according to  claim 1 , characterized by being a Monolithic-Microwave-Integrated-Circuit structure on a semiconductor board.  
     
     
         31 . A circuit according to  claim 30 , characterized in that the circuit is of symmetrical structure with respect to said first series circuit and said second series circuit.  
     
     
         32 . A circuit according to  claim 31 , characterized by common through holes for grounding pairs of said means having controllable resistance, each pair consisting of one means connected to a junction between two inductors of said first series circuit and one means connected to a junction between two inductors of said second series circuit.  
     
     
         33 . A circuit according to  claim 1 , characterized in that every junction point between two inductors in said first or second series circuit is connected to a means having controllable resistance, and all of the means having controllable resistance are controlled on the basis of a common signal is provided at a single terminal.