| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable amplifier that is suitable for use in a digital signal processing system. SOLUTION: A digital signal DL to be amplified is digitally amplified based on data GM supplied from a control section 15 externally. A D/A converter 12 converts the digital signal DLM that is digitally amplified into an analog signal SLA, which is fed to an analog attenuator 13 consisting of switching elements Q0-Q23 and load resistors R0-R23, r0-r23. The analog attenuator 13 applies on /off control to the switching elements Q0-Q23 depending on data GA supplied externally from the control section 15 and attenuates the analog signal SLA with a voltage division ratio of the load resistors R0-R23, r0-r23 and output an attenuated analog signal SLB. The analog attenuator 13 can variably adjust the overall amplification factor by adjusting optionally the digital data GM, GA. |
