| 摘要 |
<p>A phase detector suitable for use in an identification circuitry of a PAL/SECAM Television Receiver or the like for identifying the line sequence, wherein the input of the phase detector is adapted to receive the differential output signals from a frequency discriminator. The phase detector includes a differential amplifier stage (102) adapted to receive the output from the frequency discriminator, a multiplier section (104) adapted to receive switching signals and a current mirror circuit (106) coupled with the outputs of the multiplier section for producing a single-ended output at an output terminal. The differential input signals are multiplied by the switching signals to produce an output signal at the output terminal of the phase detector the sense of which is determined by the phase relationship between the differential input signals and the switching signal. The phase detector includes a rectifier section (142-152) having an input connected to the single-ended output of the differential amplifier section and a pair of outputs connected to the inputs of the multiplier section. Error current components produced in the amplifier section are substantially eliminated by the addition of the rectifier section and do not appear at the output of the phase detector.</p> |
