| 摘要 |
PURPOSE:To digitize a phase adjustment circuit which adjusts the phase of a reference signal in such a way that the sensitivity of a lock-in detection becomes largest out of a signal processing circuit used for the lock-in detection. CONSTITUTION:A programmable timer 401 performs a counting-up operation, it inverts the value of a binary output signal when a counted content reaches a predetermined number (m), it outputs an output signal having a period corresponding to a prescribed frequency, and it outputs a counted content during a counting operation. An adder 405 adds a number corresponding to a predetermined phase adjustment amount to the counted content which has been output, and it outputs an added result. A phase shifter 404 compares the added result with the (m), it inverts the value of the output signal when the added result is larger than the (m), and it generates a reference signal. |
