Circuit arrangement for an optical receiver
AssigneeAlcatel
InventorReinhold Jung
Life of this patent
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Abstract
Optical receivers with a photodiode (PD) and a transimpedance amplifier are optimized for signals with a particular transmission rate. A circuit is provided whereby the optical receiver can be adapted to different transmission rates. To attain this object, the feedback resistor of the transimpedance amplifier is divided into at least two resistors (R.sub.F1, R.sub.F2) connected in series. According to the transmission rate, the respective optimum resistance value is switched into the negative-feedback path with the aid of a control circuit. This makes it possible to operate such a universal optical receiver in a broadband subscriber interface both at a transmission rate of 150 Mb/s and at a transmission rate of 600 Mb/s, for example.
Claims12
A circuit arrangement for an optical receiver having a negative feedback path comprising a photodiode (PD) and a transimpedance amplifier (TIV), with the photodiode (PD) connected between a supply voltage source (U.sub.B) and an input of the transimpedance amplifier (TIV) or between the input of the transimpedance amplifier (TIV) and ground, and the transimpedance amplifier (TIV) comprising a first amplifier stage (V1), a second amplifier stage (V12) and a negative-feedback resistor forming the negative feedback path, an input of the first amplifier stage (V1) being connected to the input of the transimpedance amplifier (TIV), and an output of the second amplifier stage (V12) being connected to an output of the transimpedance amplifier (TIV), characterized in
- that the negative-feedback resistor is connected as a series combination of two resistors (R.sub.F1, R.sub.F2) between the input and output of the transimpedance amplifier (TIV), and
- that between a junction of the first and second amplifier stages (V1, V12) and a junction of the two feedback resistors (R.sub.F1, R.sub.F2), an amplifier (V22) is connected which has essentially a same transfer function as the second amplifier stage (V12) and includes means for switching the amplifier (V22) to an active state or a blocked state.
A circuit for an optical receiver having negative feedback comprising:
- photodiode (PD) means, responsive to optical signals, for providing photodiode output signals;
- transimpedance amplifier means (TIV), responsive to the photodiode output signals, for providing corresponding electrical signals, the transimpedance amplifier means (TIV) having an input and an output and including:
- first amplifier means (V1) with an input connected to the input of the transimpedance amplifier means (TIV),
- second amplifier means (V12) with a given transfer function and with an output connected to the output of the transimpedance amplifier means (TIV), the first amplifier means (V1) being coupled to the second amplifier means (V12) at an amplifier junction,
- negative-feedback resistor means for forming said negative feedback having at least two resistors (R.sub.F1, R.sub.F2) connected in series between the input and output of the transimpedance amplifier means (TIV) and being coupled at a resistor junction,
- controllable amplifier means (V22) having a substantially similar transfer function as the given transfer function of the second amplifier means (V12), the controllable amplifier means (V22) being connected between the amplifier junction and the resistor junction and having means for switching between an active state or a blocked state.
Dependencies are inferred from the claim text.