RU2271605C2 - Radio transmitting device incorporating provision for adapting to load - Google Patents

Abstract

FIELD: radio engineering; radio communications.

SUBSTANCE: proposed short-wave radio transmitting device designed for operation into mismatched load has exciter 1, adjustable stage 3 and output stage 6, power supply in the form of pulsed power module 5 having drooping characteristic that provides for constant power supply to load and maintains field voltage across stage at level ensuring its operation under critical (optimal) conditions, pulse-width controller 4, and reference-voltage supply 12, as well as differential amplifiers 9, 13, multipliers 8, 11, output-signal peak value sensor 2, input-stage input-current sensor 10, and output-stage peak voltage sensor 7.

EFFECT: enhanced output power and commercial efficiency.

1 cl, 1 dwg

Description

The invention relates to radio engineering and can be used in radio communications.

A radio transmitter with automatic adaptation to the load, consisting of an exciter, an adjustable stage, a power amplifier and a power supply with a falling characteristic at a stable output power, consisting of a PWM controller, a power key module, a current sensor, a multiplier, a reference voltage source, and a differential amplifier.

Known technical solutions [1] aimed at stabilizing the output power of the transmitters by controlling the excitation voltage by a signal from a power sensor passing into the load. However, such stabilization is possible only with the incomplete use of transistors of the output stage in voltage, i.e. with reduced efficiency. The output power can be stabilized with high efficiency according to [2] by controlling the supply voltage and pulse amplitude, i.e. by sensors of residual voltage and output power.

The main disadvantage of such stabilization is that an output power sensor with its own frequency response is required, which leads to an additional increase in the frequency response of the transmitting path in the operating frequency range.

Closest to the invention in technical essence is a transmitting device [3]. However, this device does not increase the industrial efficiency of the transmitter, it assumes operation in the VHF band in FM mode and is not intended for operation in KB communication systems requiring linear power amplification.

The objective of the invention is to increase the output power and industrial efficiency KB of a radio transmitter operating on a mismatched load.

The problem is achieved in that in the known radio transmitting device, consisting of a series-connected exciter, adjustable and output stages, a power source, consisting of a power pulse module, a reference voltage source, a series-connected second multiplier and a second differential amplifier, the output of which is connected to the control input PWM controller, between the input of the adjustable stage and the power bus of the output stage, an input signal amplitude sensor is introduced, the first eremnozhitel and a first differential amplifier whose output is connected in series with the control input of the controlled stage.

To increase the efficiency during operation of the transmitter for a mismatched load, a switching power supply with a falling control characteristic is used, at which the power supplied to the load is constant, and the excitation voltage regulation of the power amplifier is maintained at a level that ensures the operation of the output stage in critical (optimal) mode.

The drawing shows a structural electrical diagram of the proposed device.

The radio transmitting device consists of an exciter "1", an amplitude sensor for the input signal "2", an adjustable stage "3", an output stage "6", a peak voltage sensor "7", the first multiplier "8", the first differential amplifier "9", PWM -controller "4", power pulse module "5", current sensor "10", second multiplier "11", voltage reference source "12" and second differential amplifier "13".

The output stage "6" of the transmitting device operates in the class "AB" mode. From the exciter "1" to the adjustable stage "3" a signal is supplied whose power is sufficient for the full use of the transistors of the output stage in voltage (i.e., critical mode) when operating at rated load. Moreover, the power consumed by the output stage "6" is determined by the level of stabilization of the power of the power pulse module "5". The signal from the current sensor "10" is fed to the input of the multiplier "11", the second input of which receives the output voltage of the power pulse module "5". At the output of the multiplier "11", a signal is generated proportional to the power consumption of the output stage "6", which, after comparison on the second differential amplifier "13" with the voltage of the reference voltage source "12", is fed to the control input of the PWM controller "4", which changes the operating mode power pulse module "5" so that the power given to them remains constant.

In this case, the nominal level of excitation for ensuring the critical mode of the transistors of the output stage depends on the supply voltage of the output stage "6" and on the load Rx.

So, if the load resistance Rx increases, the amplitude of the current pulse of the drains of the transistors of the output stage "6" increases, the signal level at the output of the peak voltage sensor "7" increases, the signal at the output of the first differential amplifier "9" increases, which goes to the control input of the adjustable stage " 3 ", the gain of the adjustable stage" 3 "drops, the excitation voltage of the output stage of the power amplifier" 6 "decreases, the current consumed by it drops, the signal level from the current sensor" 10 "decreases, the signal level decreases output of the second multiplier "11", as a result of comparison with the signal from the reference voltage source "12" on the second differential amplifier "13" is formed an error signal supplied to the control input of the PWM controller "4". The voltage at the output of the power pulse module "5" increases to a value at which the signal level at the output of the second multiplier "11" is equalized with the reference voltage. Thus, by increasing the voltage and proportionally reducing the current, the auto-regulation system will retain the power consumed by the output stage "6". On the contrary, if the load resistance Rx decreases, the amplitude of the current pulse of the drains of the transistors of the output stage "6" decreases, the signal level at the output of the peak voltage sensor "7" decreases, the signal at the output of the first differential amplifier "9" decreases, supplied to the control input of the adjustable stage " 3 ", the gain of the adjustable stage" 3 "grows, the excitation voltage of the output stage of the power amplifier" 6 "increases, the current consumed by it increases, the signal level from the current sensor" 10 "increases, it grows at Ram signal at the output of the second multiplier "11". As a result of its comparison with the signal from the reference voltage source “12”, an error signal is generated at the second differential amplifier “13” and supplied to the control input of the PWM controller “4”. The voltage at the output of the power pulse module "5" is reduced to a value at which the signal level at the output of the second multiplier "13" is equalized with the reference voltage. Thus, by lowering the voltage and proportionally increasing the current, the auto-regulation system will save the power consumed by the output stage "6". In both cases, the result of auto-regulation is matching the output stage resistance with the load Rx.

The current and supply voltage of the output stage "6" is limited by the maximum allowable values for the applied type of transistors.

In addition, in the absence of an excitation voltage, the autoregulation system increases the supply voltage of the transistors of the output stage "6" to a maximum, in this case, when a signal with a steep leading edge arrives from the exciter "1", the danger arises that the transistors of the output stage "6" enter a very overstressed mode . In this case, breakdown of transistors of the output stage "6" by a negative pulse is not excluded.

To solve this problem, the signal from the amplitude detector of the input signal "2" is supplied to the first input of the multiplier "8", the voltage of the output stage "6" is supplied to the second input of the multiplier "8". The resulting signal is compared on a differential amplifier "9" with the signal from the peak voltage sensor "7", the received error signal from the output of the differential amplifier "9" is fed to the control input of the adjustable amplifier "3", in the absence of an excitation voltage, reducing the gain of the adjustable stage " 3 "to a minimum. As a result, the steep leading edge of the input signal does not overload the output stage "6".

Information sources.

1. Broadband radio transmitting devices. M .: "Communication" 1978, edited by Alekseev.

2. Copyright certificate No. 1136306 (USSR) "Device for automatic stabilization of power." Weiner. G.A., Korchagin Yu.V. and other publ. 1985 BI No. 3

3. Copyright certificate No. 2168859 (RF) "Transmitting device". Belyakov A.I. Publ. 2001, BI No. 16.

Claims (1)

A radio transmitting device with automatic adaptation to a changing load, containing a series-connected exciter, adjustable and output stages, a power source consisting of a power pulse module controlled from a pulse-width controller, and a reference voltage source, as well as including a first differential amplifier, whose inverting input is the output signal of the first multiplier, one of the inputs of which is connected to the amplitude sensor of the input signal of the adjustable kada, the second differential amplifier, the inverting input of which receives the output signal of the second multiplier, one of the inputs of which is connected to the current consumption sensor of the output stage, the second input of the first differential amplifier connected to the peak voltage sensor of the output stage, the result of comparing the output signal of the second multiplier with voltage the reference voltage source on the second differential amplifier is supplied to the control input of the pulse-width controller, different t m, that the output power of SMPS module is connected to the output stage and to the second inputs of the first and second multipliers.