US3624414A - Circuit arrangement for polarity reversal of signals from a signal source - Google Patents

Circuit arrangement for polarity reversal of signals from a signal source Download PDF

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Publication number
US3624414A
US3624414A US884449A US3624414DA US3624414A US 3624414 A US3624414 A US 3624414A US 884449 A US884449 A US 884449A US 3624414D A US3624414D A US 3624414DA US 3624414 A US3624414 A US 3624414A
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United States
Prior art keywords
amplifier
signal source
polarity
signals
arrangement
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Expired - Lifetime
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US884449A
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English (en)
Inventor
Leonardus Petrus Jozef Va Dijk
Geerlof Jan Korevaar
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B14/00—Transmission systems not characterised by the medium used for transmission
    • H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
    • H04B14/04—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse code modulation
    • H04B14/042—Special circuits, e.g. comparators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H03M1/12—Analogue/digital converters
    • H03M1/14—Conversion in steps with each step involving the same or a different conversion means and delivering more than one bit

Definitions

  • the polarity reversal arrangement is provided with a bridge composed of resistors wherein the signal source is connected [52] US. Cl 307/262, to one end of a diagonal branch of the bridge and wherein the 307/229, 307/236, 307/261, 321/8, 328/26, input circuit of an amplifier reversing the polarity of the input 328/140 signal is connected to the other end of this diagonal branch [51 lnt.
  • the invention relates to a circuit arrangement for polarity reversal of signals from a signal source, which circuit arrangement is provided with two series-arranged electronic switching elements.
  • Such circuit arrangements for polarity reversal are used inter alia in pulse code modulation transmission devices for generating rectified speech signals by means of polarity reversal, in particular the rectified speech signals thus obtained are applied to a pulse code modulator for generating the pulse code groups to be transmitted which are transferred to the receiver together with a polarity pulse characterizing the polarity of the speech signals to be transmitted.
  • the circuit arrangement for polarity reversal is provided with a bridge composed of resistors, the signal sourcebeing connected to one end of a diagonal branch of the bridge and the input circuit of an amplifier which reverses the polarity of the input signal being connected to the other end of this diagonal branch, the series arrangement of the two electronic switching elements being included between the ends of the other diagonal branch, the junction of the electronic switching elements being connected to the output circuit of the amplifier while the output signals of the polarity reversal arrangement are derived from one end of the last-mentioned diagonal branch of the bridge.
  • FIG. I shows a circuit arrangement for polarity reversal according to the invention
  • FIG. 2 shows a modification of the circuit FIG. 1.
  • the circuit arrangement shown in FIG. I for polarity reversal according to the invention is intended for generating rectified signals by means of polarity reversal in the band of 0.3--l0 kHz., which signals originate from a signal source including output terminals 2, 3 and an internal resistor 4, the output terminal 2 of said source being connected to a point of fixed potential, for example, earth potential, and the other output terminal 3 of the source being connected to the input circuit of the circuit arrangement which for the purpose of polarity reversal of the signals from the signal source 1 is provided with two series-arranged electronic switching elements 5, 6 in the form of diodes.
  • the output signals of the circuit arrangement are applied for handling in a user 7, for example, a pulse code modulator to an amplifier 8 having a high input resistance.
  • the polarity reversal arrangement according to the invention is provided with a bridge composed of resistors 9, 10, 11, 12, the signal source 1 being connected to one end 13 of a diagonal branch of the bridge and the input circuit of an amplifier I5, which reverses the polarity of the input signal,
  • the diode 6 Dependent on the speech signal originating from the signal source 1 having a positive or negative polarity, the diode 6 will be conducting and the diode 5 will be blocked or conversely the diode 5 will be conducting and the diode 6 will be blocked, the amplifier 15 being negatively fed back either across the resistor II or across the resistor 12 through the then conducting diode.
  • the diode 5 will be opened when the signal voltage at the diagonal point 13 connected to the signal source I is negative and the amplifier 15 will be negatively fed back through the resistor 12, the diagonal point 14 connected to the input circuit of the amplifier 15 being maintained substantially at earth potential due to the negative feedback likewise as is the case for a positive signal voltage.
  • the rectified signals from the signal source 1 occur in a balanced form at the diagonal points l7, 16, the rectified signals at the diagonal point 17 in the embodiment shown being utilized for further handling in the user 7.
  • the polarity reversal in the circuit arrangement shown occurs exactly at the instant of the alternations of polarity of the signals to be transmitted so that due to the high amplification factor of the amplifier l5 and the negative feedback effect disturbing phenomena are prevented such as, for example, ageing phenomena, distortions in the amplifier l5 and the diodes S, 6, but also temperature effects and direct current drift phenomena since the negative feedback circuits of the amplifier also function as direct voltage negative feedback circuits.
  • the signal source 1 is formed by a current source these direct current drift phenomena even exert no influence at all on the polarity reversal since due to the high internal resistance of the current source 1 the diagonal point 13 connected to the current source will assume the same potential as that of the diagonal point 14 connected to the input of the amplifier 15, so that consequently a voltage difference between these diagonal points 13, 14 will not occur in the absence of a speech signal. If the signal source 1 is formed by a voltage source, the already slight influence of the direct current drift of the amplifier 15 can still further be reduced without disturbing the course of the current in the bridge by using an additional direct voltage negative feedback circuit in the amplifier 15 especially constructed for this purpose in the manner as is shown in the Figure.
  • the amplifier 15 is provided with an input amplifier stage 21 employing a field effect transistor (FET), the source electrode being connected to the input of the subsequent amplifier stage 22 whilst the FET 21 which, as is known, has a very high input impedance is fed by a current source incorporated in the source electrode circuit in the form of a difference amplifier 23 provided with transistors 24, 25 having a common emitter resistor 26.
  • FET field effect transistor
  • the base electrode of the transistor 24 is connected to earth potential through resistor 27, and the base electrode of the transistor 25 is connected to the output circuit of the amplifier 15 through a low-pass filter which does not pass signal frequencies and is composed of series resistors 28, 29 and shunt capacitors 30, 31.
  • the direct current drift of the amplifier 15 is compensated for in the manner of a direct voltage negative feedback. If a direct current drift occurs, for example, at the output of the amplifier 15, the collector current of the transistor 24 and hence the current through the FET 21 will consequently start to vary low-pass filter 28-31 and the transistor 25 as a result of which also the voltage between the control electrode and the source electrode of the FET 21 will vary which voltage variation will bring about the direct current drift compensation of the amplifier 15 without a direct current being introduced into the control electrode circuit, or in other words, without the course of the current in the bridge 9-12 being disturbed.
  • Resistor 26 3 K1] Resistor 27: [0 K0 FET 21; BFW I I.
  • the polarity reversal arrangement provides the great advantage of a great frequency independence, particularly the polarity reversal arrangement shown can be used for the lowest signal frequencies as occur, for example, in video signals.
  • the rectified output signals may be derived, for example, both in a balanced form and in single phase, and the possibility of capacitive coupling of the signal source 1 and the output amplifier 8 is provided without having to use extreme capacitances due to the possibility of using a. signal source 1 having a high internal resistance and an output amplifier 8 having a high input resistance.
  • the transformer is preferably incorporated between the diagonal points 13, 14.
  • the polarity reversal takes place by the signals from the signal source 1 itself while using switching elements in the form of diodes 5, 6, whereas the polarity reversal in the circuit arrangement of FIG. 2 is effected by separate control signals, for example, for use of a circuit arrangement for pulse code demodulation shown in FIG. 2.
  • the circuit arrangement of FIG. 2 is adapted for demodulation of pulse groups transmitted with the aid of pulse code modulation, wherein the first pulse wave always functions as a polarity pulse and the other pulses in a pulse group characterize the amplitude value of the rectified speech signal.
  • Elements corresponding to those in FlG. 1 have the same reference numerals in FIG. 2.
  • the circuit arrangement for pulse code demodulation shown in FlG. 2 the pulse groups received through line 32 are applied to a pulse code demodulator 35 after suppressing the polarity pulse in an inhibitor gate 34; samplings occurring at the output circuit of the pulse code demodulator 35 which samplings have the variation shown in the time diagram 37 upon transmission of, for example, the signal as is illustrated in the time diagram 19 of FIG, 1.
  • Both the inhibitor gate 34 and the pulse code demodulator 35 are controlled by a local pulse generator 33 which is accurately synchronized at the frequency of the received pulse groups, for example, by means of cotransmitted synchronizing pulses.
  • An AND-gate 38 controlled by the local pulse generator 33 is also connected to the line 32 for selection of the polarity pulses in the pulse groups, which selection gate 38 is succeeded by an inverter 39 connected to the local pulse generator 33 and has two output lines 40, 41 for the control of a bistable trigger 42 which is likewise provided with two control lines 43, 44 for the electronic switching elements 45, 46 of the polarity reversal arrangement, each electronic switching element 45, 46 being provided with a control electrode and, for example, formed by field effect transistors.
  • the polarity pulses selected in the AND-gate 38 and consisting of l pulses at a position polarity and 0 pulses at a negative polarity are applied to the inverter 39 which applies a pulse to output line 40 in case of a 1 pulse as a polarity pulse and which applies a pulse to output line 41 in case of a 0 pulse as a polarity pulse, the bistable trigger 42 assuming one stable state as a result of the pulses of the output line 40 and assuming the other stable state as a result of the pulses of the output line 41.
  • the control signals for the electronic switching elements 45, 46 are derived in this manner from the output circuits 43, 44 of the bistable trigger 42, which switching elements are consequently brought, for example, from their blocked condition to the conducting condition.
  • the bistable trigger 42 supplies either a control signal for the electronic switching element 46 through control line 43, or a control signal for the electronic switching element 45 through control line 44, the polarity reversal being effected in the manner as already described with reference to FIG. 1 due to the mentioned control of the electronic switching elements 45, 46.
  • a 1 pulse occurs as a polarity pulse indicating a signal of positive polarity to be transmitted
  • the electronic switching element 46 is conducting and the sampling, which is then present at the output of the pulse code demodulator 35, occurs with positive polarity at the diagonal point 17 and with negative polarity at the diagonal point 16
  • the electronic switching element 45 is conducting so that the sampling, which is then present at the output of the pulse code demodulator 35, occurs with negative polarity at the diagonal point 17 and with positive polarity at the output of the diagonal point 16.
  • the samplings of the rectified signal at the diagonal point 13 shown in the time diagram 37 are converted by the polarity reversal arrangement into the samplings of the original signal which samplings are shown for the purpose of illustration in time diagrams 47, 48.
  • the samplings of the original signal occur in a balanced form at the diagonal points l6, 17 of the bridge, the diagonal point 17 likewise as in FIG. 1 being connected through an amplifier 49 having a high input resistance to a user 50, for example, a time multiplex distributor,
  • a circuit arrangement for polarity reversal of signals from a signal source which circuit arrangement is provided with two series-arranged electronic switching elements, characterized in that the polarity reversal arrangement is provided with a bridge composed of resistors, the signal source being connected to one end of a diagonal branch of the bridge and the input circuit of an amplifier which reverses the polarity of the input signal being connected to the other end of the said diagonal branch.
  • the series arrangement of the two electronic switching elements being included between the ends of the other diagonal branch, the junction of the electronic switching elements being connected to the output circuit of the amplifier while the output signals of the polarity reversal arrangement are derived from one end of the last-mentioned diagonal branch of the bridge.
  • a circuit arrangement as claimed in claim I wherein the amplifier is provided with an input amplifier stage employing a field effect transistor, the control electrode of said input amplifier stage being connected to the said end of the diagonal branch of the bridge and the source electrode being connected to a succeeding amplifier stage, while the input amplifier stage is fed by a current source in the form of a difference amplifier employing two transistors, the base electrode of one transistor being connected to a point of fixed potential and the base electrode of the other transistor being connected to the output of the amplifier through a low-pass filter which does not pass signal frequencies.
  • each electronic switching element is provided with a control electrode which are brought to their conducting condition by control signals through control lines connected to the control electrodes.

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Amplitude Modulation (AREA)
  • Electronic Switches (AREA)
US884449A 1968-12-21 1969-12-12 Circuit arrangement for polarity reversal of signals from a signal source Expired - Lifetime US3624414A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6818490A NL6818490A (de) 1968-12-21 1968-12-21

Publications (1)

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US3624414A true US3624414A (en) 1971-11-30

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ID=19805469

Family Applications (1)

Application Number Title Priority Date Filing Date
US884449A Expired - Lifetime US3624414A (en) 1968-12-21 1969-12-12 Circuit arrangement for polarity reversal of signals from a signal source

Country Status (10)

Country Link
US (1) US3624414A (de)
JP (1) JPS4928781B1 (de)
AT (1) AT297096B (de)
BE (1) BE743445A (de)
CH (1) CH503428A (de)
DE (1) DE1960699B2 (de)
FR (1) FR2026815A1 (de)
GB (1) GB1259719A (de)
NL (1) NL6818490A (de)
SE (1) SE352503B (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4228368A (en) * 1978-10-26 1980-10-14 Orban Robert A Polarity correcting circuit
US4495626A (en) * 1981-06-25 1985-01-22 International Business Machines Corporation Method and network for improving transmission of data signals between integrated circuit chips
US4860311A (en) * 1987-05-01 1989-08-22 Cpt Corporation Method and apparatus for automatically converting input pulse train signals to output signals of desired polarity
US4866297A (en) * 1986-08-23 1989-09-12 Horiba, Ltd. Processing circuit for use with DC-voltage-output type sensors

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1458499A (en) * 1972-11-09 1976-12-15 Square D Co Logic systems
IT1108198B (it) * 1978-09-13 1985-12-02 Cselt Centro Studi Lab Telecom Perfezionamenti ai codificatori analogici digitali

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3112449A (en) * 1961-09-29 1963-11-26 Gen Electric Converter for converting alternating current signals to proportional constant polarity signals including compensating diode feedback
US3130325A (en) * 1960-08-01 1964-04-21 Electronic Associates Electronic switch having feedback compensating for switch nonlinearities
US3196291A (en) * 1963-03-18 1965-07-20 Gen Electric Precision a.c. to d.c. converter
US3311835A (en) * 1963-03-22 1967-03-28 Weston Instruments Inc Operational rectifier
US3480794A (en) * 1966-10-20 1969-11-25 Weston Instruments Inc Parallel operational rectifiers
US3509372A (en) * 1967-11-22 1970-04-28 Honeywell Inc Operational amplifier controlling opposite-conductivity type switches for providing unipolar output proportional to absolute value of input signal

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3130325A (en) * 1960-08-01 1964-04-21 Electronic Associates Electronic switch having feedback compensating for switch nonlinearities
US3112449A (en) * 1961-09-29 1963-11-26 Gen Electric Converter for converting alternating current signals to proportional constant polarity signals including compensating diode feedback
US3196291A (en) * 1963-03-18 1965-07-20 Gen Electric Precision a.c. to d.c. converter
US3311835A (en) * 1963-03-22 1967-03-28 Weston Instruments Inc Operational rectifier
US3480794A (en) * 1966-10-20 1969-11-25 Weston Instruments Inc Parallel operational rectifiers
US3509372A (en) * 1967-11-22 1970-04-28 Honeywell Inc Operational amplifier controlling opposite-conductivity type switches for providing unipolar output proportional to absolute value of input signal

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4228368A (en) * 1978-10-26 1980-10-14 Orban Robert A Polarity correcting circuit
US4495626A (en) * 1981-06-25 1985-01-22 International Business Machines Corporation Method and network for improving transmission of data signals between integrated circuit chips
US4866297A (en) * 1986-08-23 1989-09-12 Horiba, Ltd. Processing circuit for use with DC-voltage-output type sensors
US4860311A (en) * 1987-05-01 1989-08-22 Cpt Corporation Method and apparatus for automatically converting input pulse train signals to output signals of desired polarity

Also Published As

Publication number Publication date
GB1259719A (en) 1972-01-12
JPS4928781B1 (de) 1974-07-30
FR2026815A1 (de) 1970-09-18
BE743445A (de) 1970-06-19
DE1960699B2 (de) 1976-06-10
NL6818490A (de) 1970-06-23
DE1960699A1 (de) 1970-07-09
AT297096B (de) 1972-03-10
SE352503B (de) 1972-12-27
CH503428A (de) 1971-02-15

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