High Performance, Low Power Consumption NMOS P-Well on Chip Charge Pump
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-27
A circuit is shown which can yield more substrate bias and/or source higher leakage current with negligible impact to power consumption. By adding a depletion device to charge a node fully to Vdd, a NMOS P-well on chip substrate generator circuit can realize an improved substrate voltage (more negative) with negligible impact on power consumption. A basic charge pump circuit is shown in Fig. 1. Since T1 is a low voltage threshold (VT) device whose gate reaches Vdd, node N19 only charges to Vdd - low VT . This limits the coupling of node N21 to Vdd - low VT (C1/CN21). By charging C1 to Vdd, the down coupling of N21 and charge transfer through T6 can be increased. By making T1 smaller and adding a small depletion device T/A shown in Fig. 2, the charging of node N19 is shared between T1 and TA.