| 摘要 |
PURPOSE:To obtain an automatic offset control circuit with less number of circuit components in which an internal offset hardly takes place in the digital receiver capable of receiving a burst signal. CONSTITUTION:An output voltage of a preamplifier circuit 2 amplifying an input digital signal is controlled to be constant when an input level of each bit of the input digital signal is lowest or at non signal. A peak level of a preamlifier reverse phase output voltage, a positive phase output voltage of the preamplifier and a difference voltage of mean values of reverse phase output voltages are amplified and fed back to an offset adjustment section of the preamplifier circujt 2. Since an output voltage of a mean value detection circuit 11 of a reference voltage, a power supply voltage fluctuation characteristic of an output voltage of a peak level detection circuit 7 for comparison object and a temperature fluctuation characteristic are well matched, the power supply voltage dependency and temperature dependency of an output offset voltage is less. |
