Patent ID: 7898349

Claim:
A triangular wave oscillation circuit, comprising: a first current source circuit for generating a current; a capacitor; a reference voltage circuit for generating a plurality of reference voltages; a comparator circuit for comparing a voltage of the capacitor with the plurality of reference voltages to output a switching signal for switching between charging and discharging of the capacitor based on a result obtained by the comparison; a charging and discharging circuit for performing one of the charging and discharging of the capacitor with the current specified by the first current source circuit in response to the switching signal from the comparator circuit; and a switch circuit for switching between the plurality of reference voltages in response to the switching signal from the comparator circuit, wherein the charging and discharging circuit includes: an inverter circuit for inverting the switching signal from the comparator circuit; a discharging reference potential generating circuit for generating a discharging reference potential which is a reference potential for discharging the capacitor; a first NMOS transistor having a drain connected with a connection point between the first current source circuit and the capacitor, and a gate connected with the discharging reference potential generated by the discharging reference potential generating circuit; a second NMOS transistor having a gate to which the switching signal is inputted through the inverter circuit, a drain connected with the gate of the first NMOS transistor, and a source connected with a source of the first NMOS transistor; and a third NMOS transistor having a gate to which the switching signal is inputted, a drain connected with a connection point between the source of the first NMOS transistor and the source of the second NMOS transistor, and a source grounded.