Controllable integrator

Abstract

Integrated circuitry for selectively introducing capacitance and for controlling the transconductance transfer function of one or more amplifiers includes concatenated differential amplifiers with one or more pairs of switchable capacitive components differentially connected across outputs of the differential amplifiers to facilitate operation over a wide range of operating frequencies under control of external signals.

What is claimed is:  
     
       1. Integrator apparatus comprising: 
       an amplifier including a pair of outputs and being responsive to differential input signals for producing differential output signals on the pair of outputs; and  
       a pair of capacitive components connected to the pair of outputs and to a common source of first control signal, the capacitive components including insulated-gate, field-effect transistors having gates connected to respective ones of the pair of outputs and having sources and drains connected in common to receive said first control signal for altering the capacitance of each pair of capacitive component in response to the first control signal applied to the sources and drains thereof.  
     
     
       2. Integrator apparatus according to  claim 1  comprising a plurality of pairs of capacitive components, each including insulated-gate, field-effect transistors having gates connected to respective ones on the pair of outputs and having sources and drains connected in common to receive the first control signal therefor for altering the capacitance of the capacitive components in response to the first control signal applied to the sources and drains of each of the plurality of pairs of capacitive components. 
     
     
       3. Integrator apparatus according to  claim 2  wherein the amplifier includes a plurality of differential amplifiers, each having a pair of outputs coupled in common to the plurality of pairs of capacitive components, and each having a pair of inputs connected in common to receive applied differential signals, at least one of the plurality of differential amplifiers also having a transfer function from inputs thereof to outputs thereof that is controllable in response to a second control signal applied thereto for altering the combined transfer function of the plurality of differential amplifiers from the inputs thereof connected in common to the differential outputs thereof coupled in common in response to applied second control signal. 
     
     
       4. Integrator apparatus according to  claim 1  wherein said amplifier includes a pair of field-effect transistors, each having a drain electrode connected to respective ones of said pair of outputs, and having source electrodes connected in common, with the source and drain electrodes of each transistor forming a conduction channel thereof, and transistors having gate electrodes connected to receive the differential input signals applied thereto to alter the conduction channel thereof; and 
       a current source connected to the drain electrode of each transistor, and another current source connected to the common connection of the source electrodes for conducting the sum of currents in the conduction channels of the pair of transistors.  
     
     
       5. Integrator apparatus according to  claim 4  wherein said another current source is adjustable to alter the transfer function of the amplifier from the gate electrodes to the pair of outputs thereof. 
     
     
       6. Integrator apparatus according to  claim 3  wherein the second control signal is adjusted to maintain substantially constant the ratio of the transconductance of the amplifier to the capacitance provided by the capacitive components in response to first control signal applied thereto. 
     
     
       7. Integrator apparatus comprising: 
       
         a plurality of differential amplifiers connected in parallel,  
       
       
         said plurality of differential amplifiers having differential inputs connected in common to receive an applied differential signal,  
       
       
         said plurality of differential amplifiers having differential outputs connected in common to output a differential amplified signal, and  
       
       
         each of said plurality of differential amplifiers having a transfer function from input thereof to output thereof, wherein each of said plurality of differential amplifiers is individually controllable in response to a respective control signal applied thereto, for altering the transfer function of a corresponding one of said plurality of differential amplifiers from the input thereof to the output thereof. 
       
     
     
       8. Integrator apparatus, comprising: 
       
         a plurality of differential amplifiers connected in parallel,  
       
       
         said plurality of differential amplifiers having differential inputs connected in common to receive an applied differential signal,  
       
       
         said plurality of differential amplifiers having differential outputs connected in common to output a differential amplified signal,  
       
       
         each of said plurality of differential amplifiers having a transfer function from input thereof to output thereof, wherein each of said plurality of differential amplifiers is individually controllable in response to a respective control signal applied thereto, for altering the transfer function of a corresponding one of said plurality of differential amplifiers from the input thereof to the output thereof, and  
       
       
         wherein each of said plurality of differential amplifiers is selectively enabled or disabled. 
       
     
     
       9. Integrator apparatus, comprising: 
       
         a plurality of differential amplifiers connected in parallel,  
       
       
         said plurality of differential amplifiers having differential inputs connected in common to receive an applied differential signal,  
       
       
         said plurality of differential amplifiers having differential outputs connected in common to output a differential amplified signal,  
       
       
         each of said plurality of differential amplifiers having a transfer function from input thereof to output thereof, wherein each of said plurality of differential amplifiers is individually controllable in response to a respective control signal applied thereto, for altering the transfer function of a corresponding one of said plurality of differential amplifiers from the input thereof to the output thereof, and  
       
       
         wherein each of said plurality of differential amplifiers is selectively controllable to expand the linear range of a combined transfer function of the integrator apparatus. 
       
     
     
       10. Integrator apparatus according to  claim 7 , further comprising a plurality of constant current sources each providing a respective control signal to a corresponding one of the plurality of differential amplifiers. 
     
     
       11. An amplifier comprising: 
       
         a plurality of differential amplifiers, each having:  
       
         a pair of gain elements having  ( i )  a pair of differential input terminals,  ( ii )  a pair of differential output terminals, and  ( iii )  a pair of common terminals; and    
       
         a controllable current source in combination with said pair of common terminals,  
       
       
         wherein said plurality of differential amplifiers are connected in parallel,  
       
       
         wherein each of said pair of differential input terminals is connected in common with the differential input terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said pair of differential output terminals is connected in common with the differential output terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said plurality of differential amplifiers has a response characteristic defined by a corresponding transfer function from said pair of input terminals to said pair of output terminals, and  
       
       
         wherein each of said controllable current source individually controls the corresponding transfer function of a respective one of said plurality of differential amplifiers. 
       
     
     
       12. An amplifier, comprising: 
       
         a plurality of differential amplifiers, each having:  
       
       
         a pair of gain elements having:  
       
       ( i )  a pair of differential input terminals,    
       ( ii )  a pair of differential output terminals, and    
       ( iii )  a pair of common terminals; and    
       
         a controllable current source in combination with said pair of common terminals,  
       
       
         wherein said plurality of differential amplifiers are connected in parallel,  
       
       
         wherein each of said pair of differential input terminals is connected in common with the differential input terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said pair of differential output terminals is connected in common with the differential output terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said plurality of differential amplifiers has a response characteristic defined by a corresponding transfer function from said pair of input terminals to said pair of output terminals,  
       
       
         wherein each of said controllable current source individually controls the corresponding transfer function of a respective one of said plurality of differential amplifiers, and  
       
       
         wherein each of said plurality of differential amplifiers is selectively enabled or disabled. 
       
     
     
       13. An amplifier, comprising: 
       
         a plurality of differential amplifiers, each having:  
       
       
         a pair of gain elements having:  
       
       ( i )  a pair of differential input terminals,    
       ( ii )  a pair of differential output terminals, and    
       ( iii )  a pair of common terminals; and    
       
         a controllable current source in communication with said pair of common terminals,  
       
       
         wherein said plurality of differential amplifiers are connected in parallel,  
       
       
         wherein each of said pair of differential input terminals is connected in common with the differential input terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said pair of differential output terminals is connected in common with the differential output terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said plurality of differential amplifiers has a response characteristic defined by a corresponding transfer function from said pair of input terminals to said pair of output terminals,  
       
       
         wherein each of said controllable current source individually controls the corresponding transfer function of a respective one of said plurality of differential amplifiers, and  
       
       
         wherein each of said plurality of differential amplifiers is selectively controllable to expand the linear range of a combined transfer function of the amplifier. 
       
     
     
       14. An amplifier comprising: 
       
         a plurality of differential amplifiers connected in parallel, each having:  
       
       
         a pair of differential input terminals;  
       
       
         a pair of differential output terminals; and  
       
       
         a controllable current source,  
       
       
         wherein each of said pair of differential input terminals is connected in common with the differential input terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said pair of differential output terminals is connected in common with the differential output terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said plurality of differential amplifiers has a response characteristic defined by a corresponding transfer function from said pair of input terminals to said pair of output terminals, and  
       
       
         wherein each of said controllable current source individually controls the corresponding transfer function of a respective one of said plurality of differential amplifiers. 
       
     
     
       15. An amplifier, comprising: 
       
         a plurality of differential amplifiers connected in parallel, each having:  
       
       
         a pair of differential input terminals;  
       
       
         a pair of differential output terminals; and  
       
       
         a controllable current source,  
       
       
         wherein each of said pair of differential input terminals is connected in common with the differential input terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said pair of differential output terminals is connected in common with the differential output terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said plurality of differential amplifiers has a response characteristic defined by a corresponding transfer function from said pair of input terminals to said pair of output terminals,  
       
       
         wherein each of said controllable current source individually controls the corresponding transfer function of a respective one of said plurality of differential amplifiers, and  
       
       
         wherein each of said plurality of differential amplifiers is selectively enabled or disabled. 
       
     
     
       16. An amplifier, comprising: 
       
         a plurality of differential amplifiers connected in parallel, each having:  
       
       
         a pair of differential input terminals,;  
       
       
         a pair of differential output terminals; and  
       
       
         a controllable current source,  
       
       
         wherein each of said pair of differential input terminals is connected in common with the differential input terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said pair of differential output terminals is connected in common with the differential output terminals of other ones of said plurality of differential amplifiers,  
       
       
         wherein each of said plurality of differential amplifiers has a response characteristic defined by a corresponding transfer function from said pair of input terminals to said pair of output terminals,  
       
       
         wherein each of said controllable current source individually controls the corresponding transfer function of a respective one of said plurality of differential amplifiers, and  
       
       
         wherein each of said plurality of differential amplifiers is selectively controllable to expand the linear range of a combined transfer function of the amplifier. 
       
     
     
       17. Integrator apparatus comprising: 
       
         a plurality of differential amplifier means for amplifying a differential signal connected in parallel,  
       
       
         said plurality of differential amplifier means having differential inputs connected in common to receive an applied differential signal,  
       
       
         said plurality of differential amplifier means having differential outputs connected in common to output a differential amplified signal, and  
       
       
         each of said plurality of differential amplifier means having a transfer function from input thereof to output thereof, wherein each of said plurality of differential amplifier means is individually controllable in response to a respective control signal applied thereto, for altering the transfer function of a corresponding one of said plurality of differential amplifier means from the input thereof to the output thereof. 
       
     
     
       18. Integrator apparatus, comprising: 
       
         a plurality of differential amplifier means for amplifying a differential signal connected in parallel,  
       
       
         said plurality of differential amplifier means having differential inputs connected in common to receive an applied differential signal,  
       
       
         said plurality of differential amplifier means having differential outputs connected in common to output a differential amplified signal,  
       
       
         each of said plurality of differential amplifier means having a transfer function from input thereof to output thereof, wherein each of said plurality of differential amplifier means is individually controllable in response to a respective control signal applied thereto, for altering the transfer function of a corresponding one of said plurality of differential amplifier means from the input thereof to the output thereof, and  
       
       
         wherein each of said plurality of differential amplifier means is selectively enabled or disabled. 
       
     
     
       19. Integrator apparatus, comprising: 
       
         a plurality of differential amplifier means for amplifying a differential signal connected in parallel,  
       
       
         said plurality of differential amplifier means having differential inputs connected in common to receive an applied differential signal,  
       
       
         said plurality of differential amplifier means having differential outputs connected in common to output a differential amplified signal,  
       
       
         each of said plurality of differential amplifier means having a transfer function from input thereof to output thereof, wherein each of said plurality of differential amplifier means is individually controllable in response to a respective control signal applied thereto, for altering the transfer function of a corresponding one of said plurality of differential amplifier means from the input thereof to the output thereof, and  
       
       
         wherein each of said plurality of differential amplifier means is selectively controllable to expand the linear range of a combined transfer function of the integrator apparatus. 
       
     
     
       20. An amplifier comprising: 
       
         a plurality of differential amplifier means for amplifying a differential signal, each having:  
       
         a pair of gain means having  ( i )  a pair of differential input means for inputting a differential signal,  ( ii )  a pair of differential output means for outputting a differential signal, and  ( iii )  a pair of common means; and    
       
         a controllable current source means for providing a current in communication with said pair of common means;  
       
       
         wherein said plurality of differential amplifier means are connected in parallel;  
       
       
         wherein each of said pair of differential input means is connected in common with the differential input means of other ones of said plurality of differential amplifier means;  
       
       
         wherein each of said pair of differential output means is connected in common with the differential output means of other ones of said plurality of differential amplifier means;  
       
       
         wherein each of said plurality of differential amplifier means has a response characteristic defined by a corresponding transfer function from said pair of input means to said pair of output means; and  
       
       
         wherein each of said controllable current source means individually controls the corresponding transfer function of a respective one of said plurality of differential amplifier means. 
       
     
     
       21. An amplifier, comprising: 
       
         a plurality of differential amplifier means for amplifying a differential signal, each having:  
       
       
         a pair of gain means having:  
       
       ( i )  a pair of differential input means for inputting a differential signal,    
       ( ii )  a pair of differential output means for outputting a differential signal, and    
       ( iii )  a pair of common means; and    
       
         a controllable current source means for providing a current in communication with said pair of common means;  
       
       
         wherein said plurality of differential amplifier means are connected in parallel;  
       
       
         wherein each of said pair of differential input means is connected in common with the differential input means of other ones of said plurality of differential amplifier means;  
       
       
         wherein each of said pair of differential output means is connected in common with the differential output means of other ones of said plurality of differential amplifier means;  
       
       
         wherein each of said plurality of differential amplifier means has a response characteristic defined by a corresponding transfer function from said pair of input means to said pair of output means,  
       
       
         wherein each of said controllable current source means individually controls the corresponding transfer function of a respective one of said plurality of differential amplifier means, and  
       
       
         wherein each of said plurality of differential amplifier means is selectively enabled or disabled. 
       
     
     
       22. An amplifier, comprising: 
       
         a plurality of differential amplifier means for amplifying a differential signal, each having:  
       
       
         a pair of gain means having:  
       
       ( i )  a pair of differential input means for inputting a differential signal,    
       ( ii )  a pair of differential output means for outputting a differential signal, and    
       ( iii )  a pair of common means; and    
       
         a controllable current source means for providing a current in communication with said pair of common means,  
       
       
         wherein said plurality of differential amplifier means are connected in parallel,  
       
       
         wherein each of said pair of differential input means is connected in common with the differential input means of other ones of said plurality of differential amplifier means,  
       
       
         wherein each of said pair of differential output means is connected in common with the differential output means of other ones of said plurality of differential amplifier means,  
       
       
         wherein each of said plurality of differential amplifier means has a response characteristic defined by a corresponding transfer function from said pair of input means to said pair of output means,  
       
       
         wherein each of said controllable current source means individually controls the corresponding transfer function of a respective one of said plurality of differential amplifier means, and  
       
       
         wherein each of said plurality of differential amplifier means is selectively controllable to expand the linear range of a combined transfer function of the amplifier. 
       
     
     
       23. An amplifier comprising: 
       
         a plurality of differential amplifier means connected in parallel, each having:  
       
       
         a pair of differential input means for inputting a differential signal,  
       
       
         a pair of differential output means for outputting a differential signal, and  
       
       
         a controllable current source means for supplying a current;  
       
       
         wherein each of said pair of differential input means is connected in common with the differential input means of other ones of said plurality of differential amplifier means;  
       
       
         wherein each of said pair of differential output means is connected in common with the differential output means of other ones of said plurality of differential amplifier means;  
       
       
         wherein each of said plurality of differential amplifier means has a response characteristic defined by a corresponding transfer function from said pair of input means to said pair of output means; and  
       
       
         wherein each of said controllable current source means individually controls the corresponding transfer function of a respective one of said plurality of differential amplifier means. 
       
     
     
       24. An amplifier, comprising: 
       
         a plurality of differential amplifier means connected in parallel, each having:  
       
       
         a pair of differential input means for inputting a differential signal,  
       
       
         a pair of differential output means for outputting a differential signal, and  
       
       
         a controllable current source means for supplying a current;  
       
       
         wherein each of said pair of differential input means is connected in common with the differential input means of other ones of said plurality of differential amplifier means,  
       
       
         wherein each of said pair of differential output means is connected in common with the differential output means of other ones of said plurality of differential amplifier means,  
       
       
         wherein each of said plurality of differential amplifier means has a response characteristic defined by a corresponding transfer function from said pair of input means to said pair of output means,  
       
       
         wherein each of said controllable current source means individually controls the corresponding transfer function of a respective one of said plurality of differential amplifier means, and  
       
       
         wherein each of said plurality of differential amplifier means is selectively enabled or disabled. 
       
     
     
       25. An amplifier, comprising: 
       
         a plurality of differential amplifier means connected in parallel, each having:  
       
       
         a pair of differential input means for inputting a differential signal,  
       
       
         a pair of differential output means for outputting a differential signal, and  
       
       
         a controllable current source means for supplying a current;  
       
       
         wherein each of said pair of differential input means is connected in common with the differential input means of other ones of said plurality of differential amplifier means,  
       
       
         wherein each of said pair of differential output means is connected in common with the differential output means of other ones of said plurality of differential amplifier means,  
       
       
         wherein each of said plurality of differential amplifier means has a response characteristic defined by a corresponding transfer function from said pair of input means to said pair of output means,  
       
       
         wherein each of said controllable current source means individually controls the corresponding transfer function of a respective one of said plurality of differential amplifier means, and  
       
       
         wherein each of said plurality of differential amplifier means is selectively controllable to expand the linear range of a combined transfer function of the amplifier. 
       
     
     
       26. A method of integrating an applied differential signal comprising the steps of: 
       
         providing a plurality of differential amplifiers connected in parallel,  
       
       
         arranging differential inputs of the plurality of differential in common to receive the applied differential signal,  
       
       
         arranging differential outputs of the plurality of differential amplifiers in common to output a differential amplified signal,  
       
       
         wherein each of the plurality of differential amplifiers has a transfer function from input thereof to output thereof, and  
       
       
         individually controlling each of said plurality of differential amplifiers in response to a respective control signal applied thereto, for altering the transfer function of a corresponding one of said plurality of differential amplifiers from the input thereof to the output thereof. 
       
     
     
       27. A method of amplifier an applied signal comprising the steps of: 
       
         providing a plurality of differential amplifiers, each having:  
       
         a pair of gain elements having  ( i )  a pair of differential input terminals,  ( ii )  a pair of differential output terminals, and  ( iii )  a pair of common terminals;    
       
         applying a current to the pair of common terminals;  
       
       
         arranging the plurality of differential amplifiers in parallel;  
       
       
         arranging each of the pair of differential input terminals in common with the differential input terminals of other ones of the plurality of differential amplifiers;  
       
       
         arranging each of the pair of differential output terminals in common with the differential output terminals of other ones of the plurality of differential amplifiers;  
       
       
         wherein each of the plurality of differential amplifiers has a response characteristic defined by a corresponding transfer function from the pair of input terminals to the pair of output terminals; and  
       
       
         individually controlling the current applied to a respective one of the plurality of differential amplifiers to individually control the corresponding transfer function thereof.