Amplifier
AssigneeNEC Corporation
InventorYutaka Sasaki
Life of this patent
Estimating the term…
Abstract
An amplifier includes an amplifying block (26) for receiving an input signal to drive a speaker (23), and a power supply block (25) for supplying an output voltage to the amplifying block. The amplifying block (26) includes a PWM-signal generation circuit (4) which converts the input signal into a PWM signal, a speaker driving circuit (20) which drives the speaker based on the PWM signal, and a duty detection circuit (8) which outputs a time difference signal proportional to a difference between the pulse width and the pulse interval of the PWM signal. The power supply block (25) controls the output voltage thereof based on the time difference signal. If the volume of a speaker (23) is loud, the amplifier increases the drive voltage of the speaker (23) to suppress distortion of the volume.
Claims9
1-8. (canceled)
An amplifier comprising an amplifying block for receiving an input signal to drive a speaker and a power supply block for supplying an output voltage to said amplifying block, wherein:
- said amplifying block comprises a PWM-signal generation circuit for converting said input signal into a PWM signal, a speaker driving circuit for driving said speaker based on said PWM signal, and a duty detection circuit for outputting a pulse width signal depending on a pulse width of said PWM signal;
- and
- said power supply block comprises a PWM control circuit for controlling the output voltage based on said pulse width signal.
Dependencies are inferred from the claim text.