Combined Positive Multiplication and Negative Voltage Conversion

This is a Combined Positive Multiplication and Negative Voltage Conversion circuit, a popular application for MAX1044/ICL7660. Here is the circuit:

This circuit can provides both negative and positive voltage. TO provide negative voltage, this circuit uses C3 and C1 which perform the reservoir and bucket. To generate the doubled positive voltage, the C4 and C2 are used as the reservoir and bucket. The use of common charge-pump driver causes this circuit has higher output impedance. [Source: MAXIM Application Note]