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EP0102174A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Improvements in or relating to transimpedance amplifiers

Assignee: AT&T Inc
•
Filing: 1983-07-20
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Granted: —
•
Expires: 2003-07-20
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Abstract

Abstract Atransimpedance amplifier allows an optical transmitter and receiver to be in close proximity to each other without fear of overloading the receiver. The improvement increases the dynamic range of the transimpedance amplifier and thereby the operating range of the receiver. A peak detector (22) at the output of an inverting amplifier (11) within the transimpedance amplifier turns on a field effect transistor (FET) circuit (23) when an AC component of an electrical signal becomes so large than the inverting amplifier would otherwise go into saturation whereby the FET circuit (23) acts as an AC shunt impedance at the input of the inverting amplifier and diverts the excess AC current to ground (30). Also, the FET circuit (23) acts as a DC resistance in concert with sense and sink current mirrors (21) and (24) to effectively divert an excessive DC component of the electrical signal away from the input of the inverting amplifier (11). Although the dynamic range of the transimpedance amplifier is increased, the optical sensitivity and the performance of the receiver remain unchanged.

Inventors

  • 👤 Lanny Starkes Smoot

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-07 19:43
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3084; H03F; H03F3/00; H03F3/04; H03F3/08; H03F3/087; H04; H04B; H04B10/00; H04B10/60; H04B10/66; H04B10/69; H04B10/691

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 97 words
A transimpedance amplifier for converting an optical signal to an electrical signal, including amplifying means (11) having an input (18) fed by means (10) for converting the optical signal (15) to a current with AC and DC components, and characterised by means (22) for comparing a signal at the output (20) of the amplifying means with a preset reference signal, impedance means (23) responsive to output from the comparing means to divert the AC component from the input of the amplifying means, and means (24) for diverting the DC component from the input of the amplifying means.
Claim 2
Dependent Claim 97 words
A transimpedance amplifier for converting an optical signal to an electrical signal, including amplifying means (11) having an input (18) fed by means (10) for converting the optical signal (15) to a current with AC and DC components, and characterised by means (22) for comparing a signal at the output (20) of the amplifying means with a preset reference signal, impedance means (23) responsive to output from the comparing means to divert the AC component from the input of the amplifying means, and means (24) for diverting the DC component from the input of the amplifying means.
Claim 3
Dependent Claim 61 words
An amplifier as claimed in claim 1 wherein the impedance means (23) is connected between the input (18) of the amplifying means and a point of reference potential (30), and there is provided means (21) for sensing the DC component, the DC component diverting means (24) being responsive to the sensing means for diverting the DC component through the impedance means.
Claim 4
Dependent Claim 16 words
An amplifier as claimed in claim 2 wherein the sensing means (21) is a current mirror.
Claim 5
Dependent Claim 22 words
4 . An amplifier as claimed in claim 2 or 3 wherein the DC component diverting means (24) is a current mirror.
Claim 6
Dependent Claim 26 words
An amplifier as claimed in any preceding claim wherein the amplifying means includes an inverting amplifier (11) with resistance means (13) connected in feedback relationship therewith.
Claim 7
Dependent Claim 17 words
An amplifier as claimed in any preceding claim wherein the optical converting means (10) is a photodiode.
Claim 8
Dependent Claim 20 words
An amplifier as claimed in any preceding claim wherein the impedance means (23) is a field effect transistor (FET) circuit.
Claim 9
Dependent Claim 37 words
8 . An amplifier as claimed in claim 7 wherein the FET circuit includes a field effect transistor (2$), and a capacitor (29) connected to the transistor for blocking the DC component and passing the AC component.
Claim 10
Dependent Claim 17 words
An amplifier as claimed in any preceding claim wherein the comparing means (22) is a peak detector.

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