| 摘要 |
A gain control circuit and its gain control method, said gain control method comprising the following steps: firstly, outputting continuously a counter value; next, generating a ramp wave signal based on said counter value, and at a voltage where a control voltage signal intersects said ramp wave signal, obtaining an initial counter value based on said ramp wave signal, thus determining an initial voltage gain of an amplifier circuit; then, when a high or low voltage of an output signal of said amplifier circuit is greater or less than a predetermined detection voltage upper or lower limit, adjusting a DC voltage level of said ramp wave signal with a detection signal; and finally, obtaining at said voltage a counter value less than said initial counter value based on said ramp wave signal, hereby reducing said initial voltage gain based on said counter value.
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