| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve a PSRR (Power Supply Rejection Ratio) of a ΔΣ A/D converter. <P>SOLUTION: A switched capacitor type D/A converter 4 converts a digital output signal D<SB POS="POST">OUT</SB>into an analog feedback voltage V<SB POS="POST">FB</SB>. The D/A converter 4 has m switch circuits 10 each of which is provided for each bit of the digital output signal D<SB POS="POST">OUT</SB>. Each switch circuit 10 includes a first switch group (M1 and M4) that is controlled to be turned on when a corresponding bit (Vdata<SB POS="POST">i</SB>) is 1 and controlled to be turned off when the bit is 0, and a second switch group (M2 and M3) that is controlled to be turned on when the corresponding bit (Vdata<SB POS="POST">i</SB>) is 0 and controlled to be turned off when the bit is 1. Each switch (M1-M4) of the first switch group and the second switch group is constituted by a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor). A ground voltage is applied to each lower power supply terminal of a first inverter 12 and a second inverter 14. <P>COPYRIGHT: (C)2012,JPO&INPIT |
