GB2194406A - Optical signal receiver circuits - Google Patents
Optical signal receiver circuits Download PDFInfo
- Publication number
- GB2194406A GB2194406A GB8717081A GB8717081A GB2194406A GB 2194406 A GB2194406 A GB 2194406A GB 8717081 A GB8717081 A GB 8717081A GB 8717081 A GB8717081 A GB 8717081A GB 2194406 A GB2194406 A GB 2194406A
- Authority
- GB
- United Kingdom
- Prior art keywords
- optical signal
- signal receiver
- reduce
- level
- receiver device
- 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
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/691—Arrangements for optimizing the photodetector in the receiver
- H04B10/6911—Photodiode bias control, e.g. for compensating temperature variations
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
- Amplifiers (AREA)
Abstract
In an optical signal receiver circuit in which a PIN diode draws current through a load resistor RL of a value dependent upon the level of a received optical signal, a zener diode Z is connected to limit the sum of the voltages developed across the PIN diode and the load resistor so as to reduce the bias voltage available for the PIN diode, and thereby its sensitivity, if received optical signals exceed a given level. <IMAGE>
Description
SPECIFICATION
Optical signal receiver circuits
The present invention relates to optical signal receiver circuits.
Electric circuits are known which utilise devices such as PIN diodes for receiving optical signals and converting them into electric signals. In such circuits a problem arises where the level of the received optical signal may vary over a wide range, since if a receiver circuit is designed to be sensitive to very low level optical signals the receiver circuit or the following circuits, or both, may be overloaded if relatively high level optical signals are received.
According to the present invention in an optical signal receiver circuit in which an optical signal receiver device is connected in series with a load impedance such that an electrical signal voltage varying in value with variations in value of a received optical signal is set up across said load impedance, voltage limiting means is connected across said series-connected receiver device and load impedance such as to reduce the level of a bias voltage applied to said device for levels of received optical signal higher than a predetermined level and thereby reduce its sensitivity.
The voltage limiting means may comprise a zener diode.
An optical signal receiver circuit in accordance with the invention will now be described by way of example with reference to the accompanying drawing, which shows the circuit diagrammatically.
Referring to the drawing the receiver circuit comprises a resistor RS, a PIN diode, a load resistor RL and a capacitor C connected in series across a bias voltage source (not shown). An amplifier A has its input connected to the junction between the PIN diode and the load resistor RL, while a subsidiary amplifier S is connected in an integrating circuit arrangement the effect of which is to establish across the capacitor C a voltage substantially of equal magnitude but of opposite polarity to the mean value developed across the load resistor RL, so that the input to the amplifier A is maintained substantially at a reference potential shown in the drawing as earth potential. The bias applied to the PIN diode is in the reverse sense, that is, positive on the cathode.
A zener diode Z is connected across the series-connected PIN diode and load resistor
RL, so that if the received optical signal level increases above a given threshold level, at which the sum of the voltages developed across the PIN diode and load resistor RL reaches the zener voltage of the diode Z, any further increase in electric current level drawn through the load resistor RL will tend to reduce the reverse bias voltage available to the
PIN diode, thereby reducing the sensitivity of the diode. By suitable choice of the values for the source resistor RS, the load resistor RL and the zener voltage of the diode Z the electric signal levels reaching the amplifier A for high level received optical signals may be arranged not to overload the amplifier A. It is possible that the bias voltage applied to the
PIN diode may actually change polarity, so that for the highest levels of received optical signal the PIN diode may be forward biased.
The optical signals may for example be conveyed to the PIN diode by way of an optical fibre path forming part of a telecommunication system, and may be of a free space wavelength of, say between 400 and 2600 nanometres.
Claims (4)
1. An optical signal receiver circuit in which an optical signal receiver device is connected in series with a load impedance such that an electrical signal voltage varying in value with variations in value of a received optical signal is set up across said load impedance, wherein voltage limiting means is connected across said series-connected receiver device and load impedance such as to reduce the level of a bias voltage applied to said device for levels of received optical signal higher than a predetermined level and thereby reduce its sensitivity.
2. An optical signal receiver circuit in accordance with Claim 1 wherein the voltage limiting means comprises a zener diode.
3. An optical signal receiver circuit comprising an amplifier, resistive impedance means connected in an input circuit to said amplifier, and an optical signal receiver device which is arranged to draw an electrical current through said resistive impedance means in response to a received optical signal, wherein there is provided voltage limiting means arranged to limit the sum of the voltages developed across said receiver device and said resistive impedance means such as to reduce the level of a bias voltage applied to said receiver device for levels of received optical signal higher than a predetermined level and thereby reduce the sensitivity of said receiver device.
4. An optical signal receiver circuit substantially as hereinbefore described with reference to the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8717081A GB2194406B (en) | 1986-07-18 | 1987-07-20 | Optical signal receiver circuits |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB868617598A GB8617598D0 (en) | 1986-07-18 | 1986-07-18 | Optical signal receiver circuits |
| GB8717081A GB2194406B (en) | 1986-07-18 | 1987-07-20 | Optical signal receiver circuits |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8717081D0 GB8717081D0 (en) | 1987-08-26 |
| GB2194406A true GB2194406A (en) | 1988-03-02 |
| GB2194406B GB2194406B (en) | 1990-07-18 |
Family
ID=26291062
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8717081A Expired - Fee Related GB2194406B (en) | 1986-07-18 | 1987-07-20 | Optical signal receiver circuits |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2194406B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2233525A (en) * | 1989-06-09 | 1991-01-09 | Stc Plc | Optical receivers |
| US5023951A (en) * | 1989-04-14 | 1991-06-11 | Northern Telecom Limited | Optical receivers |
| EP0433468A1 (en) * | 1989-12-18 | 1991-06-26 | Hewlett-Packard GmbH | Current voltage converter |
| EP0782251A1 (en) * | 1995-12-29 | 1997-07-02 | Thomson Broadcast Systems | Detector with automatic bias control of a PIN photodiode |
-
1987
- 1987-07-20 GB GB8717081A patent/GB2194406B/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5023951A (en) * | 1989-04-14 | 1991-06-11 | Northern Telecom Limited | Optical receivers |
| GB2233525A (en) * | 1989-06-09 | 1991-01-09 | Stc Plc | Optical receivers |
| GB2233525B (en) * | 1989-06-09 | 1994-02-16 | Stc Plc | Optical receivers |
| EP0433468A1 (en) * | 1989-12-18 | 1991-06-26 | Hewlett-Packard GmbH | Current voltage converter |
| US5123732A (en) * | 1989-12-18 | 1992-06-23 | Hewlett-Packard Company | Optical time domain reflectometer and current voltage converter for use therein |
| EP0782251A1 (en) * | 1995-12-29 | 1997-07-02 | Thomson Broadcast Systems | Detector with automatic bias control of a PIN photodiode |
| FR2743224A1 (en) * | 1995-12-29 | 1997-07-04 | Thomson Broadcast Systems | DETECTION DEVICE COMPRISING MEANS FOR AUTOMATICALLY PROVIDING THE SENSITIVITY OF A PIN PHOTODIODE |
| US5889605A (en) * | 1995-12-29 | 1999-03-30 | Thomson Broadcast Systems | Detection device including means for automatically slaving the sensitivity of a pin photodiode |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2194406B (en) | 1990-07-18 |
| GB8717081D0 (en) | 1987-08-26 |
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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 |