DE3035945A1 - Full wave active rectifier using operational amplifier inverter - coupled in series with switch between input and output with parallel controlled switch path - Google Patents

Abstract

The rectifier has a signal input (10) coupled on the one hand via an inverter (12) and a switch (14) to the signal output (16) and coupled to it on the other hand via a single switch (15), both the switches (14,15) being controlled by the input signal. The latter is fed initially to a comparator (17), the output of which controls one switch (15) directly and controls the other switch via a NOR gate (18). Pref. high-pass filters (11,13) are inserted between the signal input (10) and the inverter (12) and between the inverter and the first switch (14) respectively. The rectifier provides a full-wave output signal which is free from spurious DC components and which does not exhibit any offset drift.

Description

Active rectifier

PRIOR ART The invention is based on a rectifier the genre of the main claim.

For the rectification of AC voltage signals, it is known, so-called Use one-way or two-way rectifier. Such rectifiers using of diodes, however, have the disadvantage that they only work with alternating voltage signals above 0.7 V - the knee voltage of the diodes - can be used. It is on known, so-called for the rectification of AC voltage signals of low amplitude To use active rectifiers, which are built with the help of operational amplifiers that simultaneously amplify and rectify the AC voltage signal. However, such active rectifiers have the disadvantage that due to offset voltages the operational amplifier DC voltage components occur, which lead to drift phenomena of the output signal.

Advantages of the Invention The rectifier according to the invention with the Characteristic features of the main claim has the advantage that No interfering DC components and therefore no offset drift occur in the output signal.

Drawing The invention is shown in the drawing and in the explained in more detail below. The only figure shows a circuit diagram an embodiment of a rectifier according to the invention.

Description of the exemplary embodiment In the figure, 10 is a Designates the input terminal to which an AC voltage signal is applied. This arrives first to a high-pass filter 11 and from there once via an inverter 12, a second high-pass filter 13 and a first switch 14 to an output terminal 16 and on the other hand directly via a second switch 15 to the output terminal 16. The first switch 14 is controlled by a comparator 17 via a non-gate 18 activated ', which is connected on the input side to the high-pass filter 11; the second switch 15 is controlled directly by comparator 17.

The operation of the rectifier shown in the figure is as follows: In the comparator 17 it is recognized whether the positive or negative half-wave of the input signal is present. Accordingly, in the positive half-wave the second Switch 15 and in the negative half-wave via the non-gate 18 the first switch 14 is closed. This means that in the positive half-wave closed-m second switch 15 sends the positive half-wave directly to the output terminal 16 and in the negative half-wave the signal passes through the inverter 12 and the then closed first switch 14 to the output terminal 16. This is at the output a fully rectified signal. The high-pass filters 11, 13 are the DC components that occur at the input or behind the inverter 12 are decoupled can. This means that the output signal is independent of drift phenomena that occur in the active elements of the rectifier.

Claims (2)

Active rectifier claims, characterized in that the Input signal once via an inverter (12) and a first switch (14) and on the other hand via a second switch (15) directly to an output (16) is, the switches directly or via a non-gate (18) from a comparator (17) to which the input signal is applied. 2. Rectifier according to claim 1, characterized in that im Input and downstream of the inverter (12) high-pass filter (11, 13) are arranged.