CS206045B1 - Double-phase generator with derivation and differntial amplifier - Google Patents

Description

(54) Two-phase generator with derivative and differential amplifier

The present invention relates to a two-phase generator with a derivative and differential amplifier.

Prior art known circuits of two-phase generators usually consist of two inverting integrators and an inverter with feedback over the entire circuit. Damping is usually introduced into this circuit in the feedback circuit of the first integrator. Positive feedback from the output of the second integrator to the second input of the inverter ensures that the oscillation is stable and maintained. The disadvantage of prior art circuits is the necessity of using three active elements, such as operational amplifiers, which increases production costs, electrical input and at the same time worsens the background distance of generators with very little non-linear distortion. The existing circuitry causes difficulties especially when the requirement to achieve higher frequencies is susceptible to oscillation even without the introduction of feedback, the non-linear distortion due to phase shift and the limited cut-off frequency for full input power strongly increases.

These two drawbacks are eliminated by a two-phase generator with a derivative and differential amplifier, which is based on the fact that the derivative amplifier is connected via an inverting input through the first capacitor and the first resistor to the common conductor. an amplitude control circuit and through a third resistor, a second capacitor with an inverting operational amplifier input having a fourth resistor connected to its output together at the node with the second output terminal and a non-inverting derivative amplifier input, while the non-inverting operational amplifier input is connected to the amplitude control circuit conductor.

The main advantage of this circuit is that it enables a simple implementation of a generator with two outputs with selectable phase shift, for example 30 °, or an optional output voltage amplitude ratio. Another advantage is the strong DC negative feedback of both amplifiers and the AC feedback between the amplifiers, reducing substantially the DC requirements of the amplifiers used. ;

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in more detail by the accompanying drawing, in which an example of connection is shown. The generator consists of the ^derivative: whom you feedback amplifier 1 connected to the differential operational amplifier inverting input of the second differentiator amplifier 1 is connected through the first capacitor 6 and the resistor 5 to the common conductor. Then

via a second resistor 7 with a derivative output. the amplifier 1 with the first output terminal 3 and through the third resistor 8, the second capacitor 9 to the node with the inverting input of the operational amplifier 2. In this node it is still connected; a fourth resistor 10 connected to the output of the operational amplifier 2 with a non-inverting derivative amplifier input; the first output terminal 3 is still connected to the amplifier control circuit 11; This way connected, second-terminal with non-inverting input of operational amplifier 2 and third terminal, s | common conductor. The amplitude control circuit 11 can be solved by the non-linearity of the amplitude transfer characteristic, by thermistors, bulbs, controlled dividers or analog multipliers. The condition is * setting and keeping the transmission coefficient K necessary to maintain harmonics. F

The principle of engagement can be best explained by mathematical justification. If in the calculation; we consider ideal elements, then for a derivative amplifier the following applies: s 3 3 = U ₄ + pTu ₄ differential opamp 2 corresponds to:

4 4 = - pTu ₃ + jSTm ₃ + KpTu ₃ where u ₃ is voltage at first output terminal 3 u ₄ is voltage at second output terminal 4 p is complex variable T is time constant

K is the transmission coefficient of the amplitude control circuit 11 where T = K ₇ C ₆ = Pi ₀ C ₉ Then the characteristic equation of the whole circuit is:

, 2K - 1 1 1 _Λ

T ²

For K = 0.5 oscillation at frequency ω = lfT. Resistors 5 and 8 are not necessary to interpret the function, they are used only to ensure the feedback loop stability at higher frequencies.

The described connection is particularly advantageous for the construction of simple two-phase generators.

Claims (1)

JT SUBJECT OF THE INVENTION; 7 '7' '...........' T ’ A two-phase derivative and differential amplifier characterized in that the derivative amplifier (1) is connected via an inverting input to the common conductor (6) and the first resistor (5) and to the output node via the second resistor (7). with the first output terminal (3), with the circuit (11) of the control ^! amplitude and through a third resistor (8), a second capacitor (9) with an inverting input of the operational amplifier (2) ί with a fourth resistor (Ój connected to its output together at the node with the second output terminal (4) and non-inverting derivative input) ), while the non-inverting input of the operational amplifier (2) is also connected to the amplitude control circuit (11) connected to the common conductor.