| 摘要 |
Provides extraction of two colour component signals from highly integrated circuit. The SECAM chrominance signal demodulator comprises an oscillator (110) operating at a controlled frequency and a phase comparator (12) with a first input (122) connected to an output (116) of the oscillator. The second input (124) is connected to receive a chrominance signal, and the output is connected to a loop input of the oscillator. A fixed current source (150) is also connected to the loop input. A current mirror (152a, 154a) is provided to copy a current which is equal to the sum of the fixed current and the comparator output in the branches (152,154) which include calibrating resistances (162, 164). Output voltages corresponding to the red and blue components of the chrominance signal are measured on the terminals of the calibrating resistances, in series with a common resistance. |
