GB2132439A - Oscillator circuit arrangements - Google Patents

Oscillator circuit arrangements Download PDF

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Publication number
GB2132439A
GB2132439A GB08334011A GB8334011A GB2132439A GB 2132439 A GB2132439 A GB 2132439A GB 08334011 A GB08334011 A GB 08334011A GB 8334011 A GB8334011 A GB 8334011A GB 2132439 A GB2132439 A GB 2132439A
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GB
United Kingdom
Prior art keywords
resistor
tolerance
capacitor
amplifier
oscillator circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08334011A
Other versions
GB8334011D0 (en
GB2132439B (en
Inventor
John Tsun Lun Ip
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co PLC filed Critical General Electric Co PLC
Priority to GB08334011A priority Critical patent/GB2132439B/en
Publication of GB8334011D0 publication Critical patent/GB8334011D0/en
Publication of GB2132439A publication Critical patent/GB2132439A/en
Application granted granted Critical
Publication of GB2132439B publication Critical patent/GB2132439B/en
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/20—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator

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  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)

Abstract

An oscillator for generating low frequency sinusoidal electric signals having stable frequency and predictable amplitude, utilising a frequency-dependent negative resistor (1) in the feedback path of an amplifier (10), to avoid the need for large inductors. <IMAGE>

Description

SPECIFICATION Oscillator circuit arrangements The present invention relates to oscillator circuit arrangements.
In particular but not exclusively the invention is concerned with oscillator arrangements for providing sinusoidal output signals at frequencies of the order of 100 Hz or less. In such oscillator arrangements the values of capacitance and inductance required to form a frequencydetermining resonant circuit tend to be undesirably large, particularly if the resonant circuit is required to have a high Q value.
According to the present invention in an oscillator circuit arrangement including amplifier means and a frequency dependent positive feedback network between the output and the input of said amplifier, said feedback network comprises resistor and capacitor means and an impedance convertor arrangement connected to form a frequency-dependent negative resistor or super capacitor.
Preferably there are provided means to limit the voltage excursion of output signals from said amplifier.
An oscillator circuit arrangement in accordance with the present invention will now be described by way of example with reference to the accompanying drawing which shows the circuit arrangement diagrammatically.
Referring to the drawing the oscillator circuit arrangement comprises an impedance convertor 1 of known form having two capacitive impedances 2 and 3 and three resistive impedances 4, 5 and 6, connected such that the convertor 1 represents a frequency-dependent negative resistor, or "super capacitor" between its input 7 and earth.
Signals from the output of one of the amplifier elements 8 of the convertor 1 are applied to an output terminal 9 and to an input of an amplifier 10, while the output signals from this amplifier 10 are returned to the input 7 by way of a voltagelimiter network 1 1 and a capacitor 12. The input 7 is also connected to earth by way of a resistor 13.
It will be seen that the convertor 1 and the resistor 1 3 together have the transfer function of a parallel LC circuit whose elements have each been multiplied by K F(s)= s where s=jw, such that the inductive element Z=sL is represented by Z'=KL (the resistor 13) and 1 Z= sC is represented by K s2C (the frequency-dependent negative resistor or super capacitor 1). On the same basis the capacitor 12 represents a series resistive element Z=R, which becomes KR Z'= s Between the input 7 and the terminal 9 the convertor 1 is arranged to act as a unity gain band-pass filter with its pass-band centred substantially on the desired frequency of oscillation. The signal amplitude at the terminal 9 therefore is that of the fundarijental component of the square-wave signal passed by the voltage limiter network 11.If the Zener diode 14 in this network may be considered to set the excursion of this square wave at a value Vref., then the amplitude of the signal at the terminal 9 is substantially 4 Vref.
7r It is known that convertors 1 of the form shown can lead to realisations of filter circuits having low sensitivity to changes in element values or to variations due to temperature. The circuit arrangement described above therefore is able to provide a sinusoidal output signal at a predictable amplitude with a low harmonic content, and with good frequency stability.
Component values for oscillator circuit arrangements of the form described above, producing output signals at 25 Hz and 50 Hz, are listed below:~ a) 25 Hz: Capacitor 2 47nF 1% tolerance Capacitor 3 47nF 1% tolerance Capacitor 12 2.7nF 1% tolerance Resistor 4 133 KS23% tolerance Resistor 5 100KQ 2%tolerance Resistor 6 100 kQ 21% tolerance Resistor 13 133 KQ 21% tolerance b) 50 Hz: : Capacitor 2 12nF 1% tolerance Capacitor 3 12nF 1% tolerance Capacitor 12 680pF 1% tolerance Resistor 4 261 KQ 2%tolerance Resistor 5 100 KQ 3% tolerance Resistor 6 100 KQ 2%tolerance Resistor 13 267 KQ -% tolerance
Claims 1. An oscillator circuit arrangement including amplifier means and a frequency-dependent positive feedback network between the output and the input of the amplifier, wherein said feedback network comprises resistor and capacitor means and an impedance convertor
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Oscillator circuit arrangements The present invention relates to oscillator circuit arrangements. In particular but not exclusively the invention is concerned with oscillator arrangements for providing sinusoidal output signals at frequencies of the order of 100 Hz or less. In such oscillator arrangements the values of capacitance and inductance required to form a frequencydetermining resonant circuit tend to be undesirably large, particularly if the resonant circuit is required to have a high Q value. According to the present invention in an oscillator circuit arrangement including amplifier means and a frequency dependent positive feedback network between the output and the input of said amplifier, said feedback network comprises resistor and capacitor means and an impedance convertor arrangement connected to form a frequency-dependent negative resistor or super capacitor. Preferably there are provided means to limit the voltage excursion of output signals from said amplifier. An oscillator circuit arrangement in accordance with the present invention will now be described by way of example with reference to the accompanying drawing which shows the circuit arrangement diagrammatically. Referring to the drawing the oscillator circuit arrangement comprises an impedance convertor 1 of known form having two capacitive impedances 2 and 3 and three resistive impedances 4, 5 and 6, connected such that the convertor 1 represents a frequency-dependent negative resistor, or "super capacitor" between its input 7 and earth. Signals from the output of one of the amplifier elements 8 of the convertor 1 are applied to an output terminal 9 and to an input of an amplifier 10, while the output signals from this amplifier 10 are returned to the input 7 by way of a voltagelimiter network 1 1 and a capacitor 12. The input 7 is also connected to earth by way of a resistor 13. It will be seen that the convertor 1 and the resistor 1 3 together have the transfer function of a parallel LC circuit whose elements have each been multiplied by K F(s)= s where s=jw, such that the inductive element Z=sL is represented by Z'=KL (the resistor 13) and 1 Z= sC is represented by K s2C (the frequency-dependent negative resistor or super capacitor 1). On the same basis the capacitor 12 represents a series resistive element Z=R, which becomes KR Z'= s Between the input 7 and the terminal 9 the convertor 1 is arranged to act as a unity gain band-pass filter with its pass-band centred substantially on the desired frequency of oscillation. The signal amplitude at the terminal 9 therefore is that of the fundarijental component of the square-wave signal passed by the voltage limiter network 11.If the Zener diode 14 in this network may be considered to set the excursion of this square wave at a value Vref., then the amplitude of the signal at the terminal 9 is substantially 4 Vref. 7r It is known that convertors 1 of the form shown can lead to realisations of filter circuits having low sensitivity to changes in element values or to variations due to temperature. The circuit arrangement described above therefore is able to provide a sinusoidal output signal at a predictable amplitude with a low harmonic content, and with good frequency stability. Component values for oscillator circuit arrangements of the form described above, producing output signals at 25 Hz and 50 Hz, are listed below:~ a) 25 Hz: Capacitor 2 47nF 1% tolerance Capacitor 3 47nF 1% tolerance Capacitor 12 2.7nF 1% tolerance Resistor 4 133 KS23% tolerance Resistor 5 100KQ 2%tolerance Resistor 6 100 kQ 21% tolerance Resistor 13 133 KQ 21% tolerance b) 50 Hz:: Capacitor 2 12nF 1% tolerance Capacitor 3 12nF 1% tolerance Capacitor 12 680pF 1% tolerance Resistor 4 261 KQ 2%tolerance Resistor 5 100 KQ 3% tolerance Resistor 6 100 KQ 2%tolerance Resistor 13 267 KQ -% tolerance Claims
1. An oscillator circuit arrangement including amplifier means and a frequency-dependent positive feedback network between the output and the input of the amplifier, wherein said feedback network comprises resistor and capacitor means and an impedance convertor arrangement connected to form a frequencydependent negative resistor, or super capacitor.
2. An oscillator circuit arrangement in accordance with Claim 1 wherein there are provided means to limit the voltage excursion of output signals from said amplifier.
3. An oscillator circuit arrangement in accordance with Claim 1 or Claim 2 wherein the resistor means and the impedance convertor arrangement have the transfer function of a parallel LC circuit.
4. An oscillator circuit arrangement substantially as hereinbefore described with reference to the accompanying drawing.
GB08334011A 1982-12-22 1983-12-21 Oscillator circuit arrangements Expired GB2132439B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08334011A GB2132439B (en) 1982-12-22 1983-12-21 Oscillator circuit arrangements

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8236406 1982-12-22
GB08334011A GB2132439B (en) 1982-12-22 1983-12-21 Oscillator circuit arrangements

Publications (3)

Publication Number Publication Date
GB8334011D0 GB8334011D0 (en) 1984-02-01
GB2132439A true GB2132439A (en) 1984-07-04
GB2132439B GB2132439B (en) 1986-03-19

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08334011A Expired GB2132439B (en) 1982-12-22 1983-12-21 Oscillator circuit arrangements

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GB (1) GB2132439B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2202704A (en) * 1987-02-04 1988-09-28 Toshiba Kk Oscillator using active b.p. filter
GB2233514A (en) * 1989-06-13 1991-01-09 Plessey Telecomm Voltage limiters

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB983736A (en) * 1962-08-17 1965-02-17 Telefunken Patent Improvements in or relating to reactance circuits
GB1248356A (en) * 1970-03-23 1971-09-29 Derek Alfred Levell Improvements in and relating to electronic oscillators and selective amplifiers

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB983736A (en) * 1962-08-17 1965-02-17 Telefunken Patent Improvements in or relating to reactance circuits
GB1248356A (en) * 1970-03-23 1971-09-29 Derek Alfred Levell Improvements in and relating to electronic oscillators and selective amplifiers

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2202704A (en) * 1987-02-04 1988-09-28 Toshiba Kk Oscillator using active b.p. filter
US4818952A (en) * 1987-02-04 1989-04-04 Kabushiki Kaisha Toshiba Oscillation circuit
GB2202704B (en) * 1987-02-04 1991-02-13 Toshiba Kk Oscillation circuit
GB2233514A (en) * 1989-06-13 1991-01-09 Plessey Telecomm Voltage limiters

Also Published As

Publication number Publication date
GB8334011D0 (en) 1984-02-01
GB2132439B (en) 1986-03-19

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19921221