| 摘要 |
<p>The invention concerns sample and hold circuits. In order to obtain a fast and precise sampling circuit, a new method is proposed for producing a switch in a sampling circuit where the switch is inserted between the input (E) of the signal to be sampled and a sample storing capacitor (C). The switch consists of a group of two diodes arranged in opposite directions (D1, D2). It is made conductive by a current output differential amplifier (AD) (i.e. having a high output impedance) which provides current as long as the output voltage (S) of the sampling circuit is not equal to the input voltage (E). It is inhibited by a voltage-tracking amplifier (AD1) which applies a zero voltage to the terminals of the diode group and prevents them from conducting g current in one direction or another. The amplifiers (AD and AD1) are alternatively activated, one during a first stage of each sampling period (memory storing stage), the other during a second stage (holding stage). The switching process is controlled by alternatively activating, by means of a CLK signal, one and then the other of the amplifiers.</p> |
