Power supply circuit and RF transponder IC

An RF transponder IC card, comprising:

• a coil antenna;
• and
• a semiconductor integrated circuit including a tuning capacitance section having a tuning capacitance, a charging capacitance section having a charging capacitance, a rectifier circuit, an analog circuit, a digital circuit, and a power supply circuit which includes a current detection circuit connected between a first power supply voltage section for applying a first power supply voltage to a first electronic circuit and a second power supply voltage section for applying a second power supply voltage to a second electronic circuit, the current detection circuit having a monitor terminal for monitoring a current flowing from the first power supply voltage section to the second power supply voltage section and a current compensation circuit connected to the first power supply voltage section and the monitor terminal, the current compensation circuit controlling a compensation current flowing from the first power supply voltage section to a ground based on the monitored current to compensate for current fluctuations caused by load fluctuations of the second electronic circuit
• wherein:
• the coil antenna is connected in parallel with the tuning capacitance section to an input of the rectifier circuit;
• the rectifier circuit has an output connected to the charging capacitance section and produces the first power supply voltage supplied to the analog circuit;
• and
• the power supply circuit produces the second power supply voltage supplied from the first power supply voltage section to the digital circuit.