| 摘要 |
<p>A control apparatus includes a means (2) for generating a first control signal (B) in accordance with the phase difference between a variable frequency signal (D) and an input signal (A) from the outside, a means (5) for multiplying said first control signal (B) and a correction signal (E) thereby to output a second control signal (H), a means (1) for outputting the variable frequency signal (D) in response to the second control signal (H), and a means (3) for generating the correction signal (E) for correcting the deviation of the variable frequency signal (D) from a predetermined value. An impedance conversion circuit which is of low input impedance and high output impedance includes a differential amplifier means (37) which, provided with a first terminal (31') which receives the reference voltage obtained by resistors and a second terminal (21) connected to an input terminal which receives an input current from the outside, outputs a signal corresponding to the voltage difference between the first and second terminals, a first current outputting means (47) for outputting a current corresponding to a signal from the differential amplifier means (37) to the second terminal (21), and a second current outputting means (52) for determining an output current against a signal from the differential amplifier means (37) and outputting the output current to an external output terminal (24).</p> |
