| 摘要 |
PURPOSE:To decrease the power consumption and occupied area per one filter, by commonly using operational amplifiers and capacitors with filters having different characteristics and multiplexing filters. CONSTITUTION:Switches SW31-34 are turned on and SWs 13-16, 20 are turned on with integration capacitors 5, 6 of the 1st characteristic BPF connected to operational amplifiers 7 and 8, output voltages of the amplifiers 7 and 8 are sampled at sampling capacitors 3, 2 and the charge in the sample capacitor 4 is discharged. An input signal is added to the output of the amplifier 7, the SWs13- 16, 20 are turned off, and the SWs11, 12, 17-19 are turned on, the output voltage of the amplifier 8 is added and integrated to the output of the amplifier 7, and the output voltage of the amplifier 7 is integrated to the output of the amplifier 8 by using the capacitor 3. The SWs11, 12, 17-19 are turned off, the operation of the BPF of the 1st characteristic is completed, and disconnected from the operational amplifiers by turning off the SWs31-34. The BPF of the 2nd characteristic makes the similar operation as the 1st BPF by using integration capacitors 9 and 10, sample capacitors 39, 1-3 and SWs connected to them. |
