Integrated Circuits and Systems group, IIT Madras

Charge pump voltage multiplier

  • Analyze the circuit in the figure below. Determine the waveforms VA and VB in steady state

  • Transistors are added to multiplex VA and VB and result in Vout. Implement this circuit using CD4069 inverters. Think carefully about which terminal goes where! You'll need to use separate ICs for the inverter and the rest of the circuitry because, on a chip, the supply and ground pins are all shorted together. You can use clock frequencies in the tens of kHz range, capacitors in the 10nF range, and a supply of 5V.

  • What is the output voltage Vout with no load(CL)? and with a constant current load IL?
  • Build and demonstrate a circuit that gives an output of approximately three times the power supply.