Chip-scale coils and isolators based thereon

Abstract

Coil structures and isolators using them. A coil(s) is (are) used as a magnetic field-generating element(s) paired with another coil(s) or other magnetic field-receiving element(s). The coil(s) is(are) formed in or on a substrate which does not include some or all of the driver (i.e., input) or receiver (i.e., output) circuits. The coil(s) and magnetic field-receiving element(s) thus can be manufactured separately from the driver and/or receiver circuitry, using different processes, instead of subjecting the chip areas containing both input and output circuits to post processing to form the coil(s). Isolators can be assembled using such coils with a resultant lower cost. Isolators also can be assembled using transformers made from such coils wherein the transformers can be driven on either of their windings in order to provide bi-directional isolation with a single transformer.

What is claimed is:  
     
         1 . A signal isolator comprising: 
 a first substrate;    a first transformer formed on the first substrate;    an input circuit operatively connected to drive the transformer in response to a received input signal;    an output circuit operatively connected to generate an output signal responsive to a signal from the transformer; and    wherein at least one of the input circuit and the output circuit is not formed on the first substrate.    
     
     
         2 . The signal isolator of  claim 1  wherein the transformer includes a first winding disposed in or on the first substrate and a second winding disposed above the first winding and electrically insulated from the first winding.  
     
     
         3 . The signal isolator of  claim 1  wherein at least one of the input circuit and the output circuit is formed in or on a semiconductor substrate which is not the first substrate.  
     
     
         4 . The signal isolator of  claim 3  wherein the input circuit is formed in or on a first semiconductor substrate and the output circuit is formed in or on a second semiconductor substrate.  
     
     
         5 . The signal isolator of  claim 4  wherein either the first semiconductor substrate or the second semiconductor substrate is the same as the first substrate.  
     
     
         6 . The signal isolator of any of claims  1 ,  3  or  4  wherein there are formed on or in the first substrate one or more elements other than the first transformer, which elements are not part of the input circuit or output circuit.  
     
     
         7 . The signal isolator of  claim 1  wherein the transformer comprises a first winding disposed on or in a first surface of the first substrate and a second winding disposed on or in an opposing second surface of the first substrate.  
     
     
         8 . The signal isolator of any of claims  1 ,  2 ,  4 ,  5  and  7  further including a Faraday shield disposed between the windings of the transformer.  
     
     
         9 . The signal isolator of any of claims  1 ,  2 ,  4 ,  5  and  7  wherein the first substrate is formed of a material having a resistivity substantially higher than 10 ohm-cm.  
     
     
         10 . The isolator of any of claims  1 - 5  further including an insulation material disposed between windings of the transformer  
     
     
         11 . The isolator of  claim 10  wherein the transformer includes a first, bottom winding and a second, top winding and a layer of dielectric material is disposed on a surface of the first substrate between the substrate and the bottom winding of the transformer.  
     
     
         12 . The isolator of  claim 11  wherein said input circuit is operatively connected to drive the second winding and said output circuit is operatively connected to receive a signal from the first winding responsive to the drive from said input circuit.  
     
     
         13 . The isolator of  claim 12  further including a second input circuit operatively connected to drive the first winding and a second output circuit operatively connected to receive a signal from the second winding responsive to the drive from the second input circuit.  
     
     
         14 . The isolator of  claim 11  wherein said input circuit is operatively connected to drive the first winding and said output circuit is operatively connected to receive a signal from the second winding responsive to the drive from said input circuit.  
     
     
         15 . A multi-channel isolator in which two or more channels are provided for communicating in opposing directions, comprising: 
 a first semiconductor substrate containing input circuitry for channels of first directionality and output circuitry for channels of second, opposing directionality;    a second semiconductor substrate containing output circuitry for channels of first directionality and input circuitry for channels of second directionality; and    a third substrate containing one or more transformers each with first windings in or on the third substrate and with second windings disposed above the first windings and with interconnections from the first substrate circuitry to the first windings and from the second substrate circuitry to the second windings.    
     
     
         16 . A signal isolator comprising: 
 a first substrate;    a coil formed in or on the first substrate for use in generating a magnetic field;    a magnetic field-receiving element formed under or over the coil and spaced therefrom by an insulator;    an input circuit operatively connected to drive the coil in response to a received input signal;    an output circuit operatively connected to generate an output signal responsive to a signal from the field-receiving element; and    wherein neither the input circuit nor the output circuit is formed on the first substrate.    
     
     
         17 . The signal isolator of  claim 16  wherein the field-receiving element includes at least one MR element.  
     
     
         18 . A method of providing signal isolation comprising: 
 providing a first substrate;    forming a first transformer on the first substrate;    operatively connecting to a first winding of the transformer an input circuit to drive the transformer in response to a received input signal; and    operatively connecting an output circuit to a second winding of the transformer to generate an output signal responsive to a signal from the transformer;    without forming at least one of the input circuit and the output circuit on the first substrate.    
     
     
         19 . The method of  claim 18  wherein the act of forming the transformer includes forming the transformer with a first winding disposed in or on the first substrate and a second winding disposed above the first winding and electrically insulated from the first winding.  
     
     
         20 . The method of  claim 18  further including: 
 forming at least one of the input circuit and the output circuit in or on a semiconductor substrate which is not the first substrate.  
 
     
     
         21 . The method of  claim 20  wherein the input circuit is formed in or on a first semiconductor substrate and the output circuit is formed in or on a second semiconductor substrate.  
     
     
         22 . The method of  claim 21  wherein either the first semiconductor substrate or the second semiconductor substrate is the same as the first substrate.  
     
     
         23 . The method of any of claims  18 ,  20  or  21  further including forming on or in the first substrate one or more elements other than the first transformer, which elements are not part of the input circuit or output circuit.  
     
     
         24 . The method of  claim 18  wherein forming the transformer includes forming a first winding disposed on or in a first surface of the first substrate and a second winding disposed on or in an opposing second surface of the first substrate.  
     
     
         25 . The method of any of claims  18 ,  19 ,  21 ,  22  and  24  further including providing a Faraday shield disposed between the windings of the transformer.  
     
     
         26 . The method of any of claims  18 ,  19 ,  21 ,  22  and  24  further including forming the first substrate of a material having a resistivity substantially higher than 10 ohm-cm.  
     
     
         27 . The method of any of claims  18 - 22  further including disposing an insulation material between windings of the transformer  
     
     
         28 . The method of  claim 27  wherein the transformer includes a first, bottom winding and a second, top winding and said method further includes disposing a layer of dielectric material on a surface of the first substrate between the substrate and the bottom winding of the transformer.  
     
     
         29 . The method of  claim 28  including operatively connecting said input circuit to drive the second winding and operatively connecting said output circuit to receive a signal from the first winding responsive to the drive from said input circuit.  
     
     
         30 . The method of  claim 29  further including operatively connecting a second input circuit to drive the first winding and a second output circuit to receive a signal from the second winding responsive to the drive from the second input circuit.  
     
     
         31 . The method of  claim 28  further including operatively connecting said input circuit to drive the first winding and said output circuit to receive a signal from the second winding responsive to the drive from said input circuit.  
     
     
         32 . A method for forming a multi-channel isolator in which two or more channels are provided for communicating in opposing directions, comprising: 
 forming on a first semiconductor substrate input circuitry for channels of first directionality and output circuitry for channels of second, opposing directionality;    forming on a second semiconductor substrate output circuitry for channels of first directionality and input circuitry for channels of second directionality;    forming on a third substrate one or more transformers each with a first winding in or on the third substrate and with a second winding disposed above said transformer's first winding; and    interconnecting the first substrate circuitry to the first windings and the second substrate circuitry to the second windings.    
     
     
         33 . A method for forming a signal isolator comprising: 
 providing a first substrate;    forming a coil in or on the first substrate for use in generating a magnetic field;    forming a magnetic field-receiving element under or over the coil and spaced therefrom by an insulator;    operatively connecting an input circuit to drive the coil in response-to a received input signal; and    operatively connecting an output circuit to generate an output signal responsive to a signal from the field-receiving element;    wherein neither the input circuit nor the output circuit is formed on the first substrate.    
     
     
         34 . The method of  claim 33  wherein the field-receiving element includes at least one MR element.  
     
     
         35 . A signal isolator comprising: 
 a first substrate;    a single transformer formed on the first substrate;    an input circuit operatively connected to drive the transformer in response to a received input signal;    an output circuit operatively connected to generate an output signal responsive to a signal from the transformer; and    wherein at least one of the input circuit and the output circuit is not formed on the first substrate.    
     
     
         36 . The signal isolator of  claim 35  wherein the transformer includes a first winding disposed in or on the first substrate and a second winding disposed above the first winding and electrically insulated from the first winding.  
     
     
         37 . The signal isolator of  claim 35  wherein at least one of the input circuit and the output circuit is formed in or on a semiconductor substrate which is not the first substrate.  
     
     
         38 . The signal isolator of  claim 37  wherein the input circuit is formed in or on a first semiconductor substrate and the output circuit is formed in or on a second semiconductor substrate.  
     
     
         39 . The signal isolator of  claim 38  wherein either the first semiconductor substrate or the second semiconductor substrate is the same as the first substrate.  
     
     
         40 . The signal isolator of  claim 35  wherein the transformer comprises a first winding disposed on or in a first surface of the first substrate and a second winding disposed on or in an opposing second surface of the first substrate.  
     
     
         41 . The signal isolator of any of claims  35 - 40  wherein the first substrate is formed of a material having a resistivity substantially higher than 10 ohm-cm.  
     
     
         42 . The isolator of any of claims  35 - 40  further including an insulation material disposed between windings of the transformer.  
     
     
         43 . The signal isolator of  claim 42  wherein the first substrate is formed of a material having a resistivity substantially higher than 10 ohm-cm.  
     
     
         44 . The isolator of any of claims  35 - 40  wherein the transformer includes a first, bottom winding and a second, top winding and a layer of dielectric material is disposed on a surface of the first substrate between the substrate and the bottom winding of the transformer.  
     
     
         45 . The isolator of  claim 44  wherein said input circuit is operatively connected to drive the second winding and said output circuit is operatively connected to receive a signal from the first winding responsive to the drive from said input circuit.  
     
     
         46 . The isolator of  claim 45  further including a second input circuit operatively connected to drive the first winding and a second output circuit operatively connected to receive a signal from the second winding responsive to the drive from the second input circuit.  
     
     
         47 . The isolator of  claim 44  wherein said input circuit is operatively connected to drive the first winding and said output circuit is operatively connected to receive a signal from the second winding responsive to the drive from said input circuit.