SU1621159A1 - Pulse-width modulator - Google Patents

Abstract

The invention relates to a pulse technique and can be used in low frequency key amplifiers, in collector modulators of transmitters and amplifiers for vibrating tables. The purpose of the invention, the expansion of the operating frequency band and an increase in the accuracy of conversion of the input signal, is achieved by measuring the repetition period of the input signal and changing the frequency of the sawtooth voltage. The pulse width modulator contains a comparator 1, a saw voltage generator 2, a controlled clock frequency generator 3, a matching unit 4, a period meter 5, a pulse counter 6, a persistent memory 7, a digital-analog converter 8. A constant is provided in the modulator optimal ratio of input and sawtooth frequencies. The accuracy of the transformations is enhanced by the constant amplitude of the sawtooth voltage. 1 hp ff, 2 ill. LO

Description

The invention relates to the field of pulsed technology and can be used in key amplifiers of low frequency, in collector modulators of transmitters and amplifiers for vibrating tables.

The aim of the invention is to expand the operating frequency band to increase the accuracy of the input signal conversion by measuring the repetition period of the input signal and changing the frequency of the sawtooth voltage in accordance with these changes.

Figure 1 shows the functional diagram of the pulse-width modulator, figure 2 shows an example of its 13 south-east knotted nodes {block of the hl cell so u)

Pulse pulse width modulator “0” is held by comparator I, driver 2 sawtooth voltage, controlled clock frequency generator 3, co-operation unit 4, period meter 5, period meter 5 connected and connected, the second outputs 4 are connected to the control unit the input of the controlled oscillator 3 clock frequency whose output is connected to the input of the driver

The 2-sawed voltage is connected with the first input, torus 1, the second input of which is connected to the input bus, oro i / gua and the input of the period meter 5 and the output of the device output bus Shaper 2 sawtooth voltage connected in series binary counter 6 pulses, permanently storing device 7 and D / A converter 8 Managed generator.

The 3-cycle frequency contains serially connected (anergore -J pulses, controlled by a frequency divider 10, the control inputs of which are connected to the inputs of the matching unit 4. The matching unit 4 can be rendered as a code converter containing a permanent storage device 4-, the first ni inputs of which connected to the first m of the period and the serpentine 5 period, the remaining n outputs of which are located and the inputs of the element (/ 1LI 4 -2 output choyu connected to the resolution input and the constant j of the storage device 4-1 . Ineny with upravlchyu 1 1 input 10 controllably degitslg frequency meter 5 shown Mauger be configured as a frequency converter - a code

Binary counter 6 pulses

data storage devices

-one

D / A converter 8 and comparator 1 are made on the basis of chips of binary counters of pulses cepf and 530, programmable permanent memory ROM (ROM)

556 series, 594 series DAC and comparator

521 series.

Pulse-width converter works as follows.

The input signal of the pulse-width modulator is fed to the input of the period meter 5 and the second input of the comparator 1.

In accordance with the length of the period of the input signal, period meter 5 generates a (gti-n) -discharge binary code converted by the matching unit 4 with the m-bit code controlling the dividing factor of the controlled section 10 i ctot which converts the signal of the i9 of the 9 impulses fM to the signal with frequency fry incoming input of driver 2 MwooopasHoro voltage, the output of which signage arrives at the first input of comparator 1 which converts the standard cm pulse of the pulse-width modulator of the torus to the sequence of width-uniformity pulses with the following frequency fT - fry / 2 depending on the frequency of the input signal FBX in accordance with the equation

fT-Fox-fKp-Fcp (1)

where gk | characterizing circle cutflf1 iii / 3KKix frequencies set ia modulator output

It follows from (1) that when the FBx changes from

-w to Ger (t IMSMSgärgs From RSr kr + FC To

about G7.

KU GKR

fVp te prktti1 bchi 2 times, because FCT and F0 “FCp. It means that

at Gwh - FO, the losses at switchings in the power amplifier, amplifying the signal of the proposed wide-pulse 1. modulator, will be practically two DC and at FBx Fcp and at any other frequency F0 Fax Fcp will be less than at PE Fcp, though more than

 Fn fq

The code converter in block 4 according to an anich translates (PL + n) -digit binary code, is proportional to the length of the input signal source signal, ShiToiO-mmpu Psnogo modul toooa, in the ГП-ORSANT binary code yn, i. the leads of the co-Tom delgchi ynpaej of what is the healer of 10 frequencies 1 Program: Eutel Core i / iv, ee The following algorithm works for the most recent bits of one (m + n) -rzz-rchdnogo code ivoTSU at least with and high and I es Гио Г i) (corresponding to the zj-top of the jro of the first signal of the input signal and the PMS of the pulse modulator exceeds some value of To), at the output l In this case, the optical element OR 4-2 contains 1, which prohibits the operation of ROM 4, and due to the local resistors and the output of the transformer, signals 1 are generated at all m of its outputs. This corresponds to the formation of a sawtooth voltage of such a frequency fT fro, that fro - fo - Fcp, where Fo 1 / T0; FCp is the cut-off frequency of the low-pass filter in the amplification system using the proposed Pulse width modulator.

Controlled divider 10 converts the frequency of the signal generator 9 pulses. ttch fiy signal frequency. supplied to the input of the former 2 sawtooth voltage by dividing by M, where M is determined by the input T-bit binary code of the controlled frequency divider 10.

Shaper 2 sawtooth voltage works as follows.

Binary counter 6 serves to generate a binary K-bit code, which periodically changes according to the law: 2 -..-. (2k-2) - (2k-1) -... etc. by counting the input frequency pulses fiy. ROM 7 converts the output K-digit binary code of a binary counter 6 into a (K-1) -bit binary code in accordance with the equations

KPZU Kech. if 0 Kech (2),

Kri3y 2k-1 is Ketch, if - 1. where the PZU is the number determined by (K -digit binary code at the output of ROM 7;

KSC is the number determined by the K-bit binary code at the output of binary counter 6.

Thus, at the output of the ROM 7, a (K-1) -bit binary code is formed, successively increasing from 0 to 2, then decreasing from 2K-1 to the OITD DAC 8 converts the digital output signal of the ROM 7 into a sawtooth voltage. whose frequency is fT fry / 2k.

Thus, the introduction of a pulse width modulator of new elements and connections allows the formation of a reference sawtooth voltage with a wide range of variation of the repetition frequency without changing its amplitude, which in turn allows

to expand the frequency range of input voltages due to the constant implementation of the optimal ratio of input and sawtooth frequencies, and to improve the accuracy of the conversion due to the constant amplitude of the saw voltage.

Claims (2)

1. A pulse width modulator containing a series-connected clock generator, a sawtooth driver, and a comparator, the output of which is connected to the output a modulator bus and a second input with an input bus, characterized in that, in order to expand the operating frequency band, a period meter connected in series and the matching unit, wherein the clock frequency generator is controllable and its control input is connected to the output of the matching unit, and the input of the period meter is connected to the input bus of the N-attenuator 2. The module according to claim 1, that is, in order to increase accuracy, the controlled generator of the active tag is made of connected together a pulse generator and controlled by a frequency divider, the control inputs are connected to the outlets of the alignment flask, the matching unit is made in the form of a code converter, and the sawtooth voltage driver is made of connected in series of a two-counter pulse counter, a persistent storage device, and a digital-to-high-frequency converter. "L 2