CS207208B1 - Double-phase generator with the difference and non-inverting integrator - Google Patents

Description

The invention relates to a two-phase generator with a differential and non-inverting integrator.

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. Existing circuitry causes difficulties especially when the requirement is to reach higher frequencies, where it 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 output power strongly increases.

Voltage with a phase shift different from 90 ° has so far been obtained by means of a summing circuit with another operational amplifier or by means of phase shifters in single-output generators.

These disadvantages are eliminated by a two-phase generator with a differential and non-inverting generator, which is based on the fact that the inverting input of the first amplifier is connected via the first capacitor to the node with its output, the first output terminal, and first through the first resistor to the node with the second output terminal with the output of the second amplifier and through the third capacitor with its inverting input coupled through the third resistor to the common conductor while the non-inverting input of the first amplifier is connected both through the second capacitor with the common conductor resistance to the amplitude control circuit connected to the common wire.

The advantage of the circuitry according to the invention is the simple construction of the generator with two output voltages with a selected phase shift, for example 20 ° or with a selected output voltage amplitude ratio.

In order to illustrate the invention, a drawing is shown with an example of connection. The differential generator consists of a first operational amplifier 1 whose non-inverting input is connected via a second | a resistor 7 with an amplitude control circuit 11 and via a second capacitor 8 with a common conductor. The inverting input of the first amplifier 1 is connected via the first resistor 5 to the node with the second output terminal 4 and through the first capacitor 6 with the first output terminal 3. This first terminal 3 is then connected to the output of the first amplifier 1 with the non-inverting input of the second amplifier. 2 and with the second terminal of the amplitude control circuit 11, which is connected to the third terminal by a common conductor. The amplitude control circuit 11 utilizes either non-linearity of the amplitude transfer characteristic or thermistors, bulbs, controlled dividers, analog multipliers, etc. The condition is to set and maintain the coefficient K necessary to maintain the harmonic oscillations.

The principle of engagement can be best explained by mathematical justification. If the ideal elements are taken into account in the calculation, the following applies to the differential integrator:

! ...... '«4 = (1 +) ^U3 | and for a non-inverting integrator:

K 1 u ₃ = —— u ₃ ——- U4 pT pT j where u ₃ is the voltage at the first output terminal 3 1 u ₄ is the voltage at the second output terminal 4 | K is the transmission of the amplitude control circuit T = ŘČ, and p is complexly variable i, for the value of the first, second and third resistances 5,7,9 we usually choose: R ₅ - R ₇ = Rj = R and for the capacities of the first, second and third capacitor 6,8,10 we choose Ce-Q-Qo-C.

After that the following equation applies to the characteristic equation of the whole circuit:

P ² + P + - ^ 3 = ⁰

In this case, it is necessary for the occurrence of harmonics to be K = 1.

: The transmission coefficient K less than 1 is reached if the time constant of the second resistor 7 and the capacitor 8 is smaller than the time constant | the first resistor 5 and the capacitor 6.

This connection can be advantageously used especially for the construction of simple and economical two-phase generators with selectable phase shift between outputs, eg 20 °, or for the implementation of a generator with a selected output voltage amplitude ratio.

Claims (1)

SUBJECT OF THE INVENTION A two-phase generator with a differential and non-inverting integrator, characterized in that the inverting input of the first amplifier (1) is connected both via the first capacitor (6) to the node and its output, with the first output terminal (3) with the amplitude control circuit (11). with the non-inverting input of the second amplifier (2) and through the first resistor (5) to the node with the second output terminal (4) with the output of the second amplifier (2) and through the third capacitor (10) with its inverting input coupled through the third resistor ( 9) with a common conductor, while the non-inverting input of the first amplifier (1) is connected both via a second capacitor (8) to the common conductor and through a second resistor (7) to the amplitude control circuit (11) connected to the common conductor.