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  said pair of capacitive component  components 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 provide by the capacitive components in response to first control signal applied thereto. 
     
     
       7. 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 capacitive element connected to the pair of outputs and to a common source of a control signal, the capacitive element including two 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 control signal for altering the capacitance of said capacitive element in response to the control signal applied to the sources and drains thereof.   
     
     
       8. Integrator apparatus according to  claim 7  further comprising a plurality of capacitive elements, each element including two 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 a respective control signal, the capacitance of each capacitive elements being altered in response to the respective control signal applied to the sources and drains thereof.   
     
     
       9. Integrator apparatus according to  claim 8  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 elements, 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. 
     
     
       10. Integrator apparatus according to  claim 9  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 elements in response to first control signal applied thereto. 
     
     
       11. Integrator apparatus according to  claim 7  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. 
       
     
     
       12. Integrator apparatus according to  claim 11  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. 
     
     
       13. Integrator apparatus comprising: 
       
         a plurality of differential amplifiers, each having:  
       
       
         a pair of inputs connected in common to receive an applied differential signal  
       
       
         a pair of outputs connected in common to output a differential amplified signal, and  
       
       
         a transfer function from inputs thereof to outputs thereof that is controllable in response to a control signal applied thereto for altering the combined transfer function of the plurality of differential amplifiers from the inputs thereof to the outputs thereof,  
       
       
         wherein the plurality of differential amplifiers are of the same conductivity type. 
       
     
     
       14. Integrator apparatus according to  claim 13 , wherein each of the plurality of differential amplifiers further comprises a controllable current source to control the transfer function in response to the control signal applied thereto. 
     
     
       15. Integrator apparatus comprising: 
       
         a plurality of differential amplifiers, each having:  
       
       
         a pair of inputs connected in common to receive an applied differential signal,  
       
       
         a pair of outputs connected in common to output a differential amplified signal, and  
       
       
         a transfer function from inputs thereof to outputs thereof that is controllable in response to a control signal applied thereto for altering the combined transfer function of the plurality of differential amplifiers from the inputs thereof to the outputs thereof,  
       
       
         wherein each of the plurality of differential amplifiers further comprises a controllable current source to control the transfer function in response to the control signal applied thereto, and  
       
       
         wherein each said controllable current source, in response to the control signal applied thereto selectively enables or disables a corresponding one of said plurality of differential amplifiers. 
       
     
     
       16. Integrator apparatus according to  claim 13 , wherein each of the plurality of differential amplifiers further comprises first and second current sources coupled respectively to drains of said differential amplifiers. 
     
     
       17. Integrator apparatus according to  claim 13 , wherein said apparatus is embodied in a MOS device. 
     
     
       18. Integrator apparatus comprising: 
       
         a plurality of differential amplifiers, each having:  
       
       
         a pair of inputs connected in common to receive an applied differential signal,  
       
       
         a pair of outputs connected in common to output a differential amplified signal, and  
       
       
         a transfer function from inputs thereof to outputs thereof that is controllable in response to a control signal applied thereto for altering the combined transfer function of the plurality of differential amplifiers from the inputs thereof to the outputs thereof,  
       
       
         a plurality of capacitive elements each with two transistors whose gates are respectively coupled to said respective pair of outputs, said two transistors having sources and drains coupled in common to receive another control signal which alters the capacitance of said capacitive element. 
       
     
     
       19. Integrator apparatus according to  claim 18 , further comprising a plurality of said capacitive elements, and wherein said control signal and said another control signal cause the integrator apparatus to be operated in a frequency range of from about  40  MHz to about  270  MHz. 
     
     
       20. Integrator apparatus according to  claim 18 , wherein said control signal and said another control signal cause the integrator apparatus to maintain a transductance to capacitance ratio substantially constant. 
     
     
       21. 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 each of said pair of differential input terminals is arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers; and  
       
       
         wherein the plurality of differential amplifiers are of the same conductivity type. 
       
     
     
       22. 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 each of said pair of differential input terminals is arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers; and  
       
       
         wherein each said controllable current source selectively enables or disables a corresponding one of said plurality of differential amplifiers. 
       
     
     
       23. 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 each of said pair of differential input terminals is arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers; and  
       
       
         wherein each of said plurality of differential amplifiers further comprises:  
       
       
         a pair of transistors in communication with said pair of differential output terminals, said pair of transistors comprising a control terminal and being arranged as a capacitance  
       
       
         wherein said control terminal is arranged and constructed for receiving a control signal for adjusting the capacitance. 
       
     
     
       24. An amplifier according to  claim 23 , further comprising a plurality of said pair of transistors, each having gates coupled in parallel, and each having sources and drains coupled together to receive said control signal. 
     
     
       25. An amplifier according to  claim 21 , wherein said amplifier comprises a CMOS device. 
     
     
       26. An amplifier according to  claim 21  wherein each of said plurality of differential amplifiers includes first and second current sources respectively coupled to said differential output terminals. 
     
     
       27. An amplifier comprising: 
       
         a plurality of differential amplifiers, 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 arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel with the differential output terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein the plurality of differential amplifiers are of the same conductivity type  
       
       
         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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers. 
       
     
     
       28. An amplifier comprising: 
       
         a plurality of differential amplifiers, 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 arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel with the differential output terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said the 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers; and  
       
       
         wherein each said controllable current source selectively enables or disables a corresponding one of said plurality of differential amplifiers. 
       
     
     
       29. An amplifier comprising: 
       
         a plurality of differential amplifiers, 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 arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers; and  
       
       
         wherein each of said plurality of differential amplifiers further comprises:  
       
       
         a pair of transistors in communication with said pair of differential output terminals, said pair of transistors comprising a control terminal and being arranged as a capacitance, wherein said control terminal is arranged and constructed for receiving a control signal for adjusting the capacitance. 
       
     
     
       30. An amplifier comprising: 
       
         a plurality of differential amplifiers, 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 arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel with the differential output terminals 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers; and  
       
       
         a plurality of said transistors each having gates coupled in parallel, and each having sources and drains coupled together to receive said control signal. 
       
     
     
       31. Integrator apparatus comprising: 
       
         an amplifier including a pair of outputs and being responsive to a differential input signal for producing differential output signals on the pair of outputs; and  
       
       
         a capacitance in communication with the pair of outputs and to a first control signal, the capacitance comprising plural transistors having gates connected to respective ones of the pair of and having sources and drains connected in common to receive said control signal for altering the capacitance in response to the first control signal applied to the sources and drains thereof. 
       
     
     
       32. Integrator apparatus according to  claim 31 , wherein said amplifier comprises a pair of semiconductor gain elements having drains coupled to said pair of outputs, sources coupled in common to receive a second control signal, and gates which receive the differential input signal. 
     
     
       33. Integrator apparatus according to  claim 31 , further comprising a plurality of said amplifiers having their outputs coupled in parallel, and their inputs coupled in parallel. 
     
     
       34. Integrator apparatus according to  claim 31 , further comprising a plurality of said capacitances having their outputs coupled in parallel. 
     
     
       35. Integrator apparatus according to  claim 31 , wherein said transistors comprise MOS transistors, and wherein the first control signal causes wide depletion regions to form adjacent said sources and drains to inhibit channels forming in the vicinities of the gates to reduce capacitance. 
     
     
       36. A semiconductor apparatus comprising: 
       
         a differential circuit including first and second outputs and being responsive to a differential input signal for producing differential output signals on the first and second outputs; and  
       
       
         a capacitance in communication with the first and second outputs and responsive to a single control signal, the capacitance comprising first and second transistors, a gate of the first transistor being in communication with the first output and a gate of the second transistor being in communication with the second output, a source and a drain of the first transistor being connected in common to receive the single control signal, a source and a drain of the second transistor being connected in common to receive the single control signal, the first control signal being applied to the sources and drains thereof for altering the capacitance. 
       
     
     
       37. A semiconductor apparatus according to  claim 36 , wherein said apparatus Comprises a MOS circuit. 
     
     
       38. A semiconductor apparatus according to  claim 36 , further comprising a plurality of differential circuits coupled in parallel, and a plurality of said first and second transistors having their gates coupled to outputs of said plurality of said differential circuits. 
     
     
       39. Integrator apparatus comprising: 
       
         a plurality of differential amplifiers, each having:  
       
       
         a pair of inputs connected in common to receive an applied differential signal  
       
       
         a pair of outputs connected in common to output a differential amplified signal, and  
       
       
         a transfer function from inputs thereof to outputs thereof that is controllable in response to a control signal applied thereto for altering the combined transfer function of the plurality of differential amplifiers from the inputs thereof to the outputs thereof,  
       
       
         wherein each of said plurality of differential amplifiers has the same conductivity type as all of the other differential amplifiers of said plurality of differential amplifiers. 
       
     
     
       40. Integrator apparatus according to  claim 39  wherein each of the plurality of differential amplifiers further comprises a controllable current source to control the transfer function in response to the control signal applied thereto. 
     
     
       41. Integrator apparatus comprising: 
       
         a plurality of differential amplifiers, each having a pair of inputs connected in common to receive an applied differential signal, a pair of outputs connected in common to output a differential amplified signal, and a transfer function from inputs thereof to outputs thereof that is controllable in response to a control signal applied thereto for altering the combined transfer function of the plurality of differential amplifiers from the inputs thereof to the outputs thereof,  
       
       
         wherein each of the plurality of differential amplifiers further comprises a controllable current source,  
       
       
         wherein each said controllable current source in response to the control signal applied thereto, selectively enables or disables a corresponding one of said plurality of differential amplifiers. 
       
     
     
       42. 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 each of said pair of differential input terminals is arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel with the differential output terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said plurality of differential amplifiers is the same conductivity type as all of the other differential amplifiers 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers. 
       
     
     
       43. An amplifier according to  claim 42  wherein each said controllable current source selectively enables or disables a corresponding one of said plurality of differential amplifiers. 
     
     
       44. 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 each of said pair of differential input terminals is arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel 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 selectively enables or disables a corresponding one of said plurality of differential amplifiers. 
       
     
     
       45. An amplifier comprising: 
       
         a plurality of differential amplifiers, 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 arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel with the differential output terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said plurality of differential amplifiers is the same conductivity type as all of the other differential amplifiers 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 controls the corresponding transfer function of a respective one of said plurality of differential amplifiers. 
       
     
     
       46. An amplifier comprising: 
       
         a plurality of differential amplifiers, 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 arranged in parallel with the differential input terminals of other ones of said plurality of differential amplifiers;  
       
       
         wherein each of said pair of differential output terminals is arranged in parallel 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 selectively enables or disables a corresponding one of said plurality of differential amplifiers.