Patent ID: 9716440
Date: 2017-07-25
CPC Classifications: H01L,H04B,H04L

Claim:
1. A receiving circuit that operates in a power supply system different from a transmitting circuit outputting a transmission signal and receives the transmission signal through an AC coupling device where a primary coil through which the transmission signal flows and a secondary coil having first and second ends and a center tap to which a specified voltage is supplied from an external terminal are magnetically coupled, comprising: a pulse width amplifier circuit including a first peak hold circuit that holds a first pulse signal with a positive amplitude appearing at a first end of the secondary coil for a first specified period of time and outputs the signal as a first hold signal, and a second peak hold circuit that holds a second pulse signal with a positive amplitude appearing at the second end of the secondary coil for a second specified period of time and outputs the signal as a second hold signal; and a comparator circuit having a first anode and a second anode that compares a voltage of the first hold signal and a voltage of the second hold signal and outputs a comparison result, wherein the first peak hold circuit comprises: a first diode element having an anode connected to the first end of the secondary coil and a cathode connected to the first anode of the comparator circuit; and a first resistor element having one end connected to the cathode of the first diode element and another end to which a reference voltage is supplied, wherein the second peak hold circuit comprises: a second diode element having an anode connected to the second end of the secondary coil and a cathode connected to the second anode of the comparator circuit; and a second resistor element having one end connected to the cathode of the second diode and another end to which the reference voltage is supplied, and wherein the pulse width amplifier circuit further includes either a third capacitor element having one end connected to the cathode of the first diode element and another end connected to the cathode of the second diode element, or a first capacitor element that accumulates charges supplied from the first end of the secondary coil through the first diode element and a second capacitor element that accumulates charges supplied from the second end of the secondary coil through the second diode element.