Patent ID: 6366125
Filing Date: 2002-04-02
Classification: H03K

Abstract:
A digital signal output circuit for transmitting data in a digital signal, said digital signal output circuit comprising:capacitor forming means connected as an integrator; charging means for selectively charging the capacitor forming means with a constant charging current; discharging means for selectively discharging the capacitor forming means with a constant discharging current; means for selectively coupling the capacitor forming means to the charging means and to the discharging means as a function of data to be transmitted by the digital signal; and a digital signal output coupled to the capacitor forming means so as to establish a rising edge of the digital signal when the capacitor forming means is coupled to the charging means and a falling edge of the digital signal when the capacitor forming means is coupled to the discharging means, wherein the constant charging current and the constant discharging current have the same magnitude so as to produce the digital signal with symmetrical rising and falling edges, the capacitor forming means is connected as an active integrator, the capacitor forming means includes an operational amplifier and a capacitor, the charging means and the discharging means are selectively coupled to the inverting input of the operational amplifier, the non-inverting input of the operational amplifier is coupled to a reference potential, and the capacitor is coupled between the inverting input and the output of the operational amplifier.