SU801234A1

SU801234A1 - Active rc-filter

Info

Publication number: SU801234A1
Application number: SU782695040A
Authority: SU
Inventors: Виктор Владимирович Маркин; Валерий Викторович Масленников; Александр Петрович Сироткин
Original assignee: Московский Ордена Трудового Красногознамени Инженерно-Физический Институт
Priority date: 1978-12-11
Filing date: 1978-12-11
Publication date: 1981-01-30

Description

Изобретение относится к радиотехнике и может использоваться в различных радиотехнических устройствах, в частности в радиоприемной аппаратуре для частотной селекции.The invention relates to radio engineering and can be used in various radio engineering devices, in particular in radio receiving equipment for frequency selection.

Известен активный RC-фильтр, содер- 5 жащий соединенные в кольцо масштабньй усилитель и два инвертирующих усилителя, между входом и выходом каждого из которых включен соответствующий конден- ; сатор, при этом между выходом масштаб- 1® ного усилителя и входом первого инвертирующего усилителя, между выходом первого и входом второго инвертирующих усилителей включены резисторыAn active RC filter is known, which contains 5 scale amplifiers connected in a ring and two inverting amplifiers, between the input and output of each of which a corresponding condenser is connected; resistor between

Однако данный фильтр имеет недостаточную добротность и недостаточно широкий диапазон рабочих частот.However, this filter has insufficient Q and a wide range of operating frequencies.

Цель изобретения - увеличение добротности и расширение диапазона рабочих частот в стерону верхних частот.The purpose of the invention is to increase the quality factor and expand the range of operating frequencies in the high frequency steron.

Указанная цель достигается тем, что в активный PC-фильтр, содержащий соединенные в кольцо масштабный усилитель и два инвертирующих усилителя между входом и выходом каждого из которых включен соответствующий конденсатор, при этом между выходом масштабного усилителя и входом первого инвертирующего усилителя, между выходом первого и входом второго инвертирующих усилителей включены резисторы, введены три регулируемых источника тока с общим управлением, подключены к выходам масштабного усилителя и инвертирующих усилителей, соответственно, и дополнительно конденсат ср и резистор, причем;масштабный усилитель и инвертирующие усилители выполнены на транзисторах, включенных по схеме с общим эмиттером, а дополнительный конденсатор включен между выходом второго инвертирующего усилителя и базой транзистора масштабного усилителя, а дополнительный резистор включен между входом фильтра и базой транзистора масштабного усилителя.This goal is achieved by the fact that an active PC filter containing a scale amplifier connected in a ring and two inverting amplifiers between the input and output of each of which includes a corresponding capacitor, while between the output of the scale amplifier and the input of the first inverting amplifier, between the output of the first and the input the second inverting amplifiers included resistors, introduced three regulated current sources with common control, connected to the outputs of a large-scale amplifier and inverting amplifiers, respectively , and additionally condensate cp and a resistor, moreover, a large-scale amplifier and inverting amplifiers are made on transistors connected according to the scheme with a common emitter, and an additional capacitor is connected between the output of the second inverting amplifier and the base of the transistor of the large-scale amplifier, and an additional resistor is connected between the filter input and the base transistor scale amplifier.

На чертеже приведена принципиальная электрическая схема предлагаемого фильтра.The drawing shows a circuit diagram of the proposed filter.

801234 4801234 4

Активный RC-фильтр содержит масштабный усилитель и два инвертирующих усилителя 2 и 3, выполненные на транзисторах 4-6, соответственно, три регулируемых источника 7-9 тока, резисторы 10, конденсаторы 11, дополнительный резистор 12, дополнительный конденсатор 13.The active RC filter contains a large-scale amplifier and two inverting amplifiers 2 and 3, made on transistors 4-6, respectively, three adjustable current sources 7-9, resistors 10, capacitors 11, an additional resistor 12, an additional capacitor 13.

Фильтр работает следующим образом.The filter works as follows.

Напряжение входного сигнала инвертируется на масштабном усилителе 1, выполненном на первом транзисторе 4 с дополнительным резистором 12. Весь выходной ток масштабного усилителя 1 при наличии регулируемого источника 7 тока протекает через резистор 10 и конденсатор 11 первого инвертирующего усилителя 2, выполненного на втором транзисторе 5. Фаза сигнала при этом изменяется приблизительно на -90°. Аналогично весь выходной ток первого инвертирующего усилителя 2 при наличии регулируемого источника 8 тока протекает через резистор 10 и конденсатор 11 второго инвертирующего усилителя 3, выполненного на третьем транзисторе 6, Фаза сигнала при этом изменяется снова на -90°.The voltage of the input signal is inverted on a scale amplifier 1 made on the first transistor 4 with an additional resistor 12. The entire output current of the scale amplifier 1, in the presence of an adjustable current source 7, flows through a resistor 10 and a capacitor 11 of the first inverting amplifier 2 made on the second transistor 5. Phase the signal changes by approximately -90 °. Similarly, the entire output current of the first inverting amplifier 2 in the presence of an adjustable current source 8 flows through the resistor 10 and the capacitor 11 of the second inverting amplifier 3, made on the third transistor 6, the phase of the signal changes again by -90 °.

Таким образом, с учетом инверсии фазы в масштабном усилителе 1 в петле обратной связи (ОС) образуется фазовый сдвиг, близкий к 360°, что приводит к резонансу напряжений на частоте, при которой коэффициент передачи в петле ОС близок к единице. Общее управление регулируемыми источниками 7-9 тока позволяет обеспечить равные режимные токи в транзисторах 4-6, что, в свою очередь, устраняет влияние внутренних эмиттерных сопротивлений транзисторов 4-6 на дополнительный фазовый сдвиг в петле ОС. При включении конденсаторов 11 в обратной связи первого и второго инвер- . тирующих усилителей 2 и 3, а также дополнительного конденсатора 13 происходит частичная компенсация влияния коллекторных емкостей транзисторов 4-6.Thus, taking into account the phase inversion in the scale amplifier 1, a phase shift close to 360 ° is formed in the feedback loop (OS), which leads to a voltage resonance at a frequency at which the transfer coefficient in the OS loop is close to unity. General control of regulated current sources 7–9 makes it possible to ensure equal operating currents in transistors 4–6, which, in turn, eliminates the effect of internal emitter resistances of transistors 4–6 on an additional phase shift in the OS loop. When you turn on the capacitors 11 in the feedback of the first and second inver. Of the amplifying amplifiers 2 and 3, as well as an additional capacitor 13, a partial compensation of the influence of the collector capacities of transistors 4-6 occurs.

В результате использования совокупности дополнительных элементов значи$ тельно увеличивается реализуемая добротность схемы и расширяется диапазон резонансных частот в сторону высших частот, что позволяет существенно расширить возможности применения микроэлект10 ронных RC-фильтров в радиоприемной аппаратуре.As a result of using a combination of additional elements, the realized Q factor of the circuit significantly increases and the range of resonant frequencies broadens towards higher frequencies, which allows us to significantly expand the possibilities of using microelectronic RC filters in radio receivers.

Claims

The invention relates to radio engineering and can be used in various radio engineering devices, in particular, in radio receiving equipment for frequency selection. An active RC filter is known that contains a large-scale amplifier connected in a ring and two inverting amplifiers between the input and output of each of which are connected to the corresponding sator, while resistors are connected between the output of the large-scale amplifier and the input of the first inverting amplifier. fi. However, this filter has an insufficient quality factor and an insufficient range of operating frequencies. The purpose of the invention is to increase the quality factor and expand the range of operating frequencies at high frequencies. This goal is achieved by the fact that in the active (C-filgr containing a large-scale amplifier connected to the ring and Two inverting amplifiers between the input and output of each of which a corresponding capacitor is connected, between the output of the main amplifier and the input of the first inverting amplifier) the output of the first and the input of the inverting amplifiers included resistors, introduced three adjustable current sources with common control, connected to the outputs of the large-scale amplifier and inverting amplifiers, respectively The condensate cp and the resistor are additionally; moreover, the main amplifier and inverting amplifiers are made on transistors connected according to the common emitter circuit, and an additional capacitor is connected between the output of the second inverting amplifier and the base transistor of the scale amplifier, and the additional resistor is connected between the filter input and base transistor scale amplifier. The drawing shows the electrical circuit of the proposed filter. Active 11 C-filter contains a scale amplifier and two inverting amplifiers 2 and 3, made on transistors 4-6, respectively, three adjustable current sources 7-9, resistors 10, capacitors 11, additional resistor 12, additional capacitor 13. The filter works in the following way. The input signal is inverted on the scale amplifier 1, performed on the first transistor 4 with an additional resistor 12. The entire output current of the scale amplifier 1 in the presence of an adjustable current source 7 flows through the resistor Yu and the capacitor 11 of the first inverting amplifier 2, made on the second transistor ee 5. The phase of the signal changes approximately by -9О. Similarly, the entire output TSS of the first inverting amplifier 2, in the presence of an adjustable current source 8, flows through the resistance 1O and the capacitor 11 of the second inverting amplifier 3 implemented on the third transistor b. In this case, the phase of the signal changes again to -90 °. Thus, taking into account the phase inversion in the scale amplifier 1, a phase shift close to 36O is formed in the feedback loop (OC), which leads to a resonance of the voltages at which the transmission coefficient in the OS loop is close to one. The overall control of adjustable current sources 7–9 allows for equal mode currents in transistors 4–6, which, in turn, eliminates the effect of the internal emitter resistances of transistors 4–6 on the additional phase shift in the OC loop. When the capacitors are turned on. 11, in the feedback of the first and second inverting amplifiers 2 and 3, as well as the additional capacitor 13, the effect of collector capacitors of transistors 4-6 is partially compensated. As a result of the use of the set of Additional Elements, the realizable quality of the circuit increases significantly and the range of resistive frequencies is expanded towards higher frequencies, which makes it possible to significantly expand the possibilities of using microelectronic RC filters in receiving equipment. Claims of the invention An active RC filter containing a scale amplifier connected in a ring and two inverting amplifiers, between the input and output of each of which a corresponding condensate is connected, between the output of the scale amplifier and the input of the first inverting amplifier, between the output of the first and the input of the second inverting amplifiers resistors, characterized in that, in order to increase the quality factor and expand the range of operating frequencies towards higher frequencies, three adjustable sources of current are introduced into it and with common control, connected to the codes of a large-scale amplifier and inverting amplifiers, respectively, and an additional capacitor and resistor, and a large-scale amplifier and inverting amplifiers are made on transistors, included in the circuit with a common emitter, and an additional capacitor is connected between the output of the second inverting amplifier and the base transistor of the scale amplifier, and an additional resistor is connected between the input of the filter and the base of the transistor of the scale amplifier. Sources of information taken into account in the examination 1. Foreign electronics, 1976, No. 18, p. 26, Fig. 14.