Multiple-input and multiple-output amplifier having pseudo-differential inputs

Abstract

The invention relates to an amplifier capable of delivering a plurality of output signals, these output signals being controlled by a plurality of input signals. A multiple-input and multiple-output amplifier of the invention comprises a common input terminal, 4 signal input terminals, 4 signal output terminals, a common terminal amplifier, 4 active sub-circuits and a feedback network. Each active sub-circuit has a sub-circuit input terminal connected to one of the signal input terminals, a sub-circuit output terminal connected to one of the signal output terminals and a sub-circuit common terminal. The feedback network has four C terminals and one R terminal. Each of said C terminals of the feedback network is coupled to the sub-circuit common terminal of one of said active sub-circuits. The output terminal of the common terminal amplifier is coupled to said R terminal of the feedback network.

The invention claimed is: 
     
       1. A multiple-input and multiple-output amplifier comprising:
 a common input terminal, n signal input terminals, n signal output terminals and a reference terminal, where n is an integer greater than or equal to 2; 
 at least one common terminal amplifier, each of the common terminal amplifiers being an amplifier comprising an input terminal and an output terminal, the input terminal of each of the common terminal amplifiers being coupled to the common input terminal; 
 a number n of active sub-circuits, each of the active sub-circuits having a sub circuit input terminal, a sub-circuit output terminal and a sub-circuit common terminal, the sub-circuit input terminal being coupled to one of the signal input terminals, the sub-circuit output terminal being coupled to one of the signal output terminals, each of the active sub-circuits being such that the current flowing out of the sub-circuit common terminal and the current flowing into the sub-circuit output terminal depend on the voltage between the sub-circuit input terminal and the sub-circuit common terminal, each of the signal input terminals being coupled to only one sub-circuit input terminal, each of the signal output terminals being coupled to only one sub-circuit output terminal; 
 a feedback network having a number n of C terminals and at least one R terminal, each of the C terminals being coupled to the sub-circuit common terminal of one of the active sub-circuits, the output terminal of each of the common terminal amplifiers being coupled to one of the R terminals, the feedback network being such that, in a known frequency band, the impedance matrix of the C terminals with respect to the R terminals connected the one to the other is a non-diagonal n×n matrix. 
 
     
     
       2. The multiple-input and multiple-output amplifier of  claim 1 , wherein the number n of signal output terminals is greater than or equal to three. 
     
     
       3. The multiple-input and multiple-output amplifier of  claim 1 , wherein at least one of the active sub-circuits is such that the current flowing out of the sub-circuit common terminal and the current flowing into the sub-circuit output terminal may be considered as only depending on the voltage between the sub-circuit input terminal and the sub-circuit common terminal. 
     
     
       4. The multiple-input and multiple-output amplifier of  claim 1 , wherein, in the known frequency band, each of the common terminal amplifiers has a small-signal voltage gain approximately equal to one, the absolute value of the output impedance of any one of the common terminal amplifiers being smaller than the absolute values of all diagonal components of the impedance matrix of the C terminals of the feedback network with respect to the R terminals of the feedback network connected the one to the other. 
     
     
       5. The multiple-input and multiple-output amplifier of  claim 1 , wherein the impedance matrix of the C terminals of the feedback network with respect to the R terminals of the feedback network connected the one to the other is, in the known frequency band, an invertible matrix. 
     
     
       6. The multiple-input and multiple-output amplifier of  claim 5 , wherein, in the known frequency band, each of the active sub-circuits has an absolute value of the ratio of the current flowing out of the sub-circuit common terminal to the voltage between the sub-circuit input terminal and the sub-circuit common terminal larger than the absolute values of all components of the inverse of the impedance matrix of the C terminals of the feedback network with respect to the R terminals of the feedback network connected the one to the other. 
     
     
       7. The multiple-input and multiple-output amplifier of  claim 1 , wherein the feedback network is composed of linear, passive and reciprocal circuit elements. 
     
     
       8. The multiple-input and multiple-output amplifier of  claim 1 , wherein the feedback network comprises one or more insulated-gate field-effect transistors. 
     
     
       9. The multiple-input and multiple-output amplifier of  claim 1 , wherein the impedance matrix of the C terminals of the feedback network with respect to the R terminals of the feedback network connected the one to the other can be adjusted by electrical means. 
     
     
       10. The multiple-input and multiple-output amplifier of  claim 1 , wherein each of said active sub-circuits comprises an internal feedback loop. 
     
     
       11. A multiple-input and multiple-output amplifier, comprising:
 a common terminal, n signal input terminals, n signal output terminals and n active sub-circuits, wherein:
 n is an integer greater than or equal to 2, 
 each signal input terminal and each signal output terminal is coupled to a unique one of the n active sub-circuits, and 
   at least one common terminal amplifier, each common terminal amplifier including an input terminal coupled to the common terminal; and   a feedback network including at least one R terminal and n C terminals, wherein:
 the at least one R terminal is coupled to an output terminal of the at least one common terminal amplifier, 
 each of the n C terminals is connected to a sub-circuit common terminal of a unique one of the n active sub-circuits, and 
 in a known frequency band, an impedance matrix of the C terminals with respect to the at least one R terminal is a non-diagonal n×n matrix. 
   
     
     
       12. The multiple-input and multiple-output amplifier of claim 11, wherein each active sub-circuit is configured such that current flowing out of the sub-circuit common terminal and current flowing into a sub-circuit output terminal depend on a voltage between a sub-circuit input terminal and the sub-circuit common terminal. 
     
     
       13. A method for multiple-input and multiple-output amplification, wherein n is an integer greater than or equal to 2, comprising:
 connecting each of n signal input terminals of an amplifier to a sub-circuit input terminal of a unique one of n active amplifier sub-circuits;   connecting each of n signal output terminals of the amplifier to a sub-circuit output terminal of a unique one of the n active amplifier sub-circuits;   connecting a common terminal of the amplifier to at least one input terminal of at least one common terminal amplifier;   connecting at least one R terminal of an amplifier feedback network to at least one output terminal of the at least one common terminal amplifier; and   connecting each of n C terminals of the amplifier feedback network to a sub-circuit common terminal of a unique one of the n active sub-circuits, wherein, in a known frequency band, an impedance matrix of the C terminals with respect to the at least one R terminal is a non-diagonal n×n matrix.   
     
     
       14. The method for multiple-input and multiple-output amplification of claim 13, further comprising:
 configuring each of the n active amplifier sub-circuits such that current flowing out of a sub-circuit common terminal and current flowing into the sub-circuit output terminal depend on a voltage between the sub-circuit input terminal and the sub-circuit common terminal.   
     
     
       15. A multiple-input and multiple-output amplifier, wherein n is an integer greater than or equal to 2, comprising:
 means for connecting each of n signal input terminals of an amplifier to a sub-circuit input terminal of a unique one of n active amplifier sub-circuits;   means for connecting each of n signal output terminals of the amplifier to a sub-circuit output terminal of a unique one of the n active amplifier sub-circuits;   means for connecting a common terminal of the amplifier to at least one input terminal of at least one common terminal amplifier;   means for connecting at least one R terminal of an amplifier feedback network to at least one output terminal of the at least one common terminal amplifier; and   means for connecting each of n C terminals of the amplifier feedback network to a sub-circuit common terminal of a unique one of the n active sub-circuits, wherein, in a known frequency band, an impedance matrix of the C terminals with respect to the at least one R terminal is a non-diagonal n×n matrix.   
     
     
       16. The multiple-input and multiple-output amplifier of claim 15, further comprising:
 means for configuring each of the n active amplifier sub-circuits such that current flowing out of a sub-circuit common terminal and current flowing into the sub-circuit output terminal depend on a voltage between the sub-circuit input terminal and the sub-circuit common terminal.