GB2222333A - Voltage to frequency converter - Google Patents
Voltage to frequency converter Download PDFInfo
- Publication number
- GB2222333A GB2222333A GB8818185A GB8818185A GB2222333A GB 2222333 A GB2222333 A GB 2222333A GB 8818185 A GB8818185 A GB 8818185A GB 8818185 A GB8818185 A GB 8818185A GB 2222333 A GB2222333 A GB 2222333A
- Authority
- GB
- United Kingdom
- Prior art keywords
- voltage
- output
- frequency converter
- comparator
- negative edge
- 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.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
- H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
- H03K3/027—Generators characterised by the type of circuit or by the means used for producing pulses by the use of logic circuits, with internal or external positive feedback
- H03K3/03—Astable circuits
- H03K3/0307—Stabilisation of output, e.g. using crystal
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
- G01R19/252—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques using analogue/digital converters of the type with conversion of voltage or current into frequency and measuring of this frequency
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K7/00—Modulating pulses with a continuously-variable modulating signal
- H03K7/06—Frequency or rate modulation, i.e. PFM or PRM
Landscapes
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
Abstract
A voltage to frequency converter comprises a free running oscillator for its timing reference and features the ability to follow fast changing signals without loss of information. The oscillator may include a crystal reference. A summed output of an input current and a feed-back current is integrated at 1 and applied to a comparator 2 to produce a logic "1" or "0" in dependence upon whether the integrated voltage is above or below zero. A counter CLR receiving clock pulses to produce an output frequency f proportional to the input voltage is periodically reset by the output of a negative edge detector 4 detecting a negative edge in the output of a Nand gate 3 receiving the outputs of comparator 2 and the counter CLR. <IMAGE>
Description
DESCRIPTION
IMPROVED VOLTAGE TO FREQUENCY CONVERTER FOR USE IN
SOLID STATE ELECTRICITY METERS
This invention relates to an improved voltage to frequency converter such as would be of use in solid state electricity meters.
Solid state electricity meters often require a voltage to frequency converter to convert the average value of a power waveform of a load expressed as a voltage into a rate output which can then be counted by a number of means. Such voltage to frequency converters designed to date suffer from temperature sensitivity and linearity problems, and also require the use of temperature stable precision capacitors to provide a timing reference. Another problem that can occur is the inability to track step changes in input voltage.
According to the present invention a voltage to frequency converter can be designed which overcomes these problems.
A specific example will now be described with reference to the accompanying drawings.
Figure 1 shows in detail the principle of a stable voltage to frequency converter.
Figure 2 shows the waveforms associated with the circuit of
Figure 1.
Referring to Figure 1 the amplifier (1) integrates the sum of -il and i2 on the capacitor in the amplifier feedback loop. The output of amplifier (1) is applied to the comparator (2) so that the comparator output is positive going for positive potential at the output of amplifier (1). If this input to the NAND gate (3) goes high or positive, its other input normally being high, then its output goes low and the negative edge detector (4) generates a positive pulse whose width approximates to the period of jF, a crystal derived clock. This positive pulse resets a four bit binary counter (5), typically found within a 74HC393, to zero so that all its outputs including the one selected will go low, hence the input to the negative edge detector will go high.An output from the binary counter selected from divided by 2, divided by 4, divided by 8 or divided by 16 will go high after the required number of transitions of jF which will then be blocked by the AND gate (6).
If the state of the comparator (2) has not changed during this time then when the selected output of the counter (5) goes high the input to the negative edge detector (4) will go low re-initiating the cycle. This will continue until the output of the canparator (2) goes low which in turn will only occur when the sum the current i2 is on an integral basis higher than the current -il.Since i2 is modulated by the output of the counter
(5) via the comparator (7) and the switching transistor (8) referred to a regulated voltage then the frequency at the output of the counter (5) will be in direct proportion to the voltage vl. An obvious advantage of the scheme described is that in the event of a step input in vl the output frequency will go to its maximum until a balance is reached, and providing the amplifier (1) does not saturate no actual information will be lost and the sum of the pulses output will relate to the envelope of vl, as long as vl is unipolar and negative.
The frequency could be derived as shown using a crystal oscillator (9) and a second four bit binary counter (10) giving a range of operating frequencies, or by any other independent stable free running oscillator.
Referring to Figure 2 a typical waveform sequence for Figure 1 is shown.
Waveform (11) shows the output of amplifier (1) integrating through 0 volts, and being restored.
Waveform (12) shows the signal .
Waveform (13) shows the output of the comparator (2).
Waveform (14) shows the output of the counter (5).
Claims (3)
1. A voltage to frequency converter based upon a crystal
controlled timing reference.
2. A voltage to frequency converter as in Claim 1 which responds
to step inputs whose output on an integral basis maintains
its veracity.
3. A voltage to frequency converter as in Claim 1 based upon any
other free running oscillator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8818185A GB2222333A (en) | 1988-07-30 | 1988-07-30 | Voltage to frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8818185A GB2222333A (en) | 1988-07-30 | 1988-07-30 | Voltage to frequency converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8818185D0 GB8818185D0 (en) | 1988-09-01 |
| GB2222333A true GB2222333A (en) | 1990-02-28 |
Family
ID=10641374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8818185A Withdrawn GB2222333A (en) | 1988-07-30 | 1988-07-30 | Voltage to frequency converter |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2222333A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015043020A1 (en) * | 2013-09-30 | 2015-04-02 | 中国科学院微电子研究所 | High-precision voltage detection circuit and method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0086140A1 (en) * | 1982-01-29 | 1983-08-17 | Enertec Societe Anonyme | High stability voltage-frequency converter |
| EP0128068A1 (en) * | 1983-05-09 | 1984-12-12 | Sangamo Weston, Inc. | Charge balance voltage-to-frequency converter utilizing CMOS circuitry |
| US4518948A (en) * | 1981-11-20 | 1985-05-21 | U.S. Philips Corporation | Analog-to-digital converter |
-
1988
- 1988-07-30 GB GB8818185A patent/GB2222333A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4518948A (en) * | 1981-11-20 | 1985-05-21 | U.S. Philips Corporation | Analog-to-digital converter |
| EP0086140A1 (en) * | 1982-01-29 | 1983-08-17 | Enertec Societe Anonyme | High stability voltage-frequency converter |
| EP0128068A1 (en) * | 1983-05-09 | 1984-12-12 | Sangamo Weston, Inc. | Charge balance voltage-to-frequency converter utilizing CMOS circuitry |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015043020A1 (en) * | 2013-09-30 | 2015-04-02 | 中国科学院微电子研究所 | High-precision voltage detection circuit and method |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8818185D0 (en) | 1988-09-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |