Semiconductor device

Abstract

A semiconductor device includes a filter circuit to sub-divide and output a received signal as a relatively low frequency first signal and a relatively high frequency second signal, a first channel containing a photocoupler to convey the first signal output from the filter circuit, a second channel containing an isolator, the isolator conveying the second signal output from the filter circuit, and a signal synthesis circuit to sum and output the first signal conveyed by way of the first channel and the second signal conveyed by way of the second channel. The isolator that is mounted in the second channel includes a capacitive coupling type isolator. The photocoupler that is mounted in the first channel contains a light emitting diode to emit light according to the first signal, and a photodiode to receive light from the light emitting diode. The isolator mounted in the second channel contains a capacitor.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a filter circuit to sub-divide and output a received signal as a relatively low frequency first signal and a relatively high frequency second signal;   a first channel containing a photocoupler to convey the first signal output from the filter circuit;   a second channel containing an isolator, the isolator conveying the second signal output from the filter circuit;   a signal synthesis circuit to sum and output the first signal conveyed by way of the first channel and the second signal conveyed by way of the second channel,
 wherein the isolator mounted in the second channel comprises a capacitive coupling type isolator, 
 wherein the photocoupler mounted in the first channel contains a light emitting diode to emit light according to the first signal, and a photodiode to receive light from the light emitting diode, and 
 wherein the isolator mounted in the second channel contains a capacitor; 
   a first semiconductor chip including the filter circuit;   a second semiconductor chip including the light emitting diode; and   a third semiconductor chip including the photodiode, the capacitor, and the signal synthesis circuit.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein the photodiode and the capacitor are formed over a single substrate in the third semiconductor chip. 
     
     
         3 . The semiconductor device according to  claim 2 , wherein the photodiode, the capacitor, and the signal synthesis circuit are formed over a single substrate in the third semiconductor chip. 
     
     
         4 . The semiconductor device according to  claim 1 , wherein the isolator mounted in the second channel comprises an inductive coupling type isolator. 
     
     
         5 . A semiconductor device, comprising:
 a first filter circuit to sub-divide and output a signal received from a first input terminal into a relatively low frequency first signal and a relatively high frequency second signal;   a second filter circuit to sub-divide and output a signal received from a second input terminal into a relatively low frequency third signal and a relatively high frequency fourth signal;   a first channel including a first photocoupler to convey the first signal output from the first filter circuit;   a second channel including a first isolator, the first isolator conveying the second signal output from the first filter circuit;   a third channel including a second photocoupler to convey a third signal output from the second filter circuit;   a fourth channel including a second isolator to convey a fourth signal output from the second filter circuit;   a first signal synthesis circuit to sum and output the first signal conveyed by way of the first channel and the second signal conveyed by way of the second channel;   a second signal synthesis circuit to sum and output the third signal conveyed by way of the third channel and the fourth signal conveyed by way of the fourth channel,
 wherein the first photocoupler mounted in the first channel includes a first light emitting diode to emit light according to the first signal, and a first photodiode to receive the light from the first light emitting diode, 
 wherein the first isolator mounted in the second channel includes a first capacitor, 
 wherein the third photocoupler mounted in the third channel includes a second light emitting diode to emit light according to the third signal, and a second photodiode to receive the light of the second light emitting diode, and 
 wherein the second isolator mounted in the fourth channel includes a second capacitor; 
   a first semiconductor chip including the first filter circuit, the second signal synthesis circuit, the second photodiode, and the second capacitor;   a second semiconductor chip including the first light emitting diode;   a third semiconductor chip including the second filter circuit, the first signal synthesis circuit, the first photodiode, and the first capacitor; and   a fourth semiconductor chip including the second light emitting diode,   wherein the second photodiode and the second capacitor are formed over a single substrate in the first semiconductor chip, and   wherein the first photodiode and the first capacitor are formed over a single substrate in the third semiconductor chip.   
     
     
         6 . The semiconductor device according to  claim 5 , wherein the first filter circuit, the second signal synthesis circuit, the second photodiode, and the second capacitor are formed over a single substrate in the first semiconductor chip, and
 wherein the second filter circuit, the first signal synthesis circuit, the first photodiode, and the first capacitor are formed over a single substrate in the third semiconductor chip.   
     
     
         7 . The semiconductor device according to  claim 5 , wherein the first isolator mounted in the second channel, and the second isolator mounted in the fourth channel, include a capacitive coupling type isolator or an inductive coupling type isolator.