Transmipedance amplifier circuit, related integrated circuit, receiver circuit and method of operating a transimpedance amplifier circuit

A method of operating a transimpedance amplifier circuit including a transimpedance amplifier and a feedback control loop including a differential integrator with an integration capacitor coupled between an input and an output of the differential integrator, the method comprising:

• during a pre-charge phase, setting a pre-charge control signal to a first value so as to set a time constant associated with charging said integration capacitor to a first time constant value;
• during an operation phase, setting said pre-charge control signal to a second value so as to increase the time constant associated with charging said integration capacitor to a second time constant value greater than the first time constant value for said pre-charge phase,
• wherein the feedback control loop has a smaller settling time for reducing or cancelling a DC/low frequency part of an input current applied to the transimpedance amplifier during said pre-charge phase, and
• wherein the feedback control loop is maintained stable during said operation phase.

A circuit, comprising:

• a transimpedance amplifier having an input and an output;
• a feedback circuit having an input coupled to the output of the transimpedance amplifier and an output coupled to an input of the transimpedance amplifier, wherein said feedback circuit comprises:
• a low pass filter including a first capacitor coupled to a first variable resistor, the low pass filter having an input coupled to the input of the feedback circuit;
• and
• a differential integrator having a first input coupled to an output of the low pass filter, a second input coupled a second variable resistor, an output coupled to the output of the feedback circuit, and a second capacitor coupled between the output of the differential integrator and the second input of the differential integrator;
• and
• a control circuit configured to set first resistance values for the first and second variable resistors when the circuit is operating in a pre-charge phase and set second resistance values for the first and second variable resistors when the circuit is operating is an operating phase.

A transimpedance amplifier circuit, comprising:

• an input terminal for receiving an input current and an output terminal for providing an output voltage;
• a transimpedance amplifier comprising an input connected to said input terminal and configured to provide at an output said output voltage, whereby said output voltage is indicative of an input current received at the input of said transimpedance amplifier;
• a feedback control loop configured to generate a compensation current at the input of said transimpedance amplifier in order reduce or cancel a DC/low frequency part of said input current, wherein said feedback control loop comprises:
• a) a differential integrator generating a feedback signal by comparing said output voltage with a reference voltage;
• and
• b) a current generator configured to generate said compensation current as a function of said feedback signal;
• wherein said differential integrator comprises at least one integration capacitor;
• wherein a time constant associated with charging said at least one integration capacitor is variable as a function of a pre-charge control signal;
• wherein said transimpedance amplifier has a variable gain that is set at least as a function of said pre-charge control signal;
• a processing circuit configured to generate said pre-charge control signal such that:
• during a pre-charge phase, said pre-charge control signal is set to a first value to set the time constant associated with charging said at least one integration capacitor to a first time constant value;
• and
• during an operation phase, said pre-charge control signal is set to a second value to increasing the time constant associated with charging said at least one integration capacitor to a second time constant value greater than the first time constant value for said pre-charge phase;
• wherein said transimpedance amplifier comprises a second operational amplifier, a first input of said second operational amplifier being connected to said input terminal and a second input of said second operational amplifier being connected to the reference voltage;
• and
• a third resistor connected between an output terminal of said second operational amplifier and said first input of said second operational amplifier.

A transimpedance amplifier circuit, comprising:

• an input terminal for receiving an input current and an output terminal for providing an output voltage;
• a transimpedance amplifier comprising an input connected to said input terminal and configured to provide at output said output voltage, whereby said output voltage is indicative of an input current received at the input of said transimpedance amplifier;
• a feedback control loop configured to generate a compensation current at the input of said transimpedance amplifier in order reduce or cancel a DC/low frequency part of said input current, wherein said feedback control loop comprises:
• a) a differential integrator generating a feedback signal by comparing said output voltage with a reference voltage;
• and
• b) a current generator configured to generate said compensation current as a function of said feedback signal;
• wherein said differential integrator comprises at least one integration capacitor;
• wherein a time constant associated with charging said at least one integration capacitor is variable as a function of a pre-charge control signal;
• wherein said transimpedance amplifier has a variable gain that is directly set as a function of said pre-charge control signal;
• and
• a processing circuit configured to generate said pre-charge control signal such that:
• during a pre-charge phase, said pre-charge control signal is set to a first value to set the time constant associated with charging said at least one integration capacitor to a first time constant value;
• and
• during an operation phase, said pre-charge control signal is set to a second value to increasing the time constant associated with charging said at least one integration capacitor to a second time constant value greater than the first time constant value for said pre-charge phase.