A balanced differential transimpedance amplifier with a single-ended input operational over a wide variation in the dynamic range of input signals. A threshold circuit is employed to either or a combination of (1) generate a varying decision threshold to ensure a proper slicing over a wide range of input current signal levels; and (2) generate a bias current and voltage applied to an input of a transimpedance stage to cancel out a dependence of the transimpedance stage voltage input on input current signal levels.

A transimpedance amplifier is provided for converting a current between its two input terminals to a voltage over its two output terminals comprising a high-speed level shifter configured for creating a difference in input DC voltage and for being transparent for alternating voltages, an input biasing network configured for reverse biasing a photodiode connected to at least one of the input terminals and transparent for a feedback signal from the feedback network which is differentially and DC-coupled with the output terminals of the voltage amplifier and outputs of the feedback network are differentially and DC-coupled with the input biasing network of which outputs are coupled with inputs of the level shifter which is differentially and DC-coupled with input terminals of the voltage amplifier.

A bandgap reference circuit includes first through fourth bipolar junction transistors (BJTs). The base and collector of the first BJT are shorted together. The second BJT is coupled to the first BJT via a first resistor. The base of the third BJT is coupled to the base of the first BJT. The base and collector of the fourth BJT are coupled together and also are coupled to the base of the second BJT. A second resistor is coupled to the fourth emitter of the fourth BJT. A third resistor is coupled to the second resistor and to the emitter of the second BJT. An operational amplifier has a first input coupled to the first resistor and the collector of the second BJT, a second input coupled to the emitter of the third BJT and the collector of the fourth BJT, and an output coupled to the collectors of the first and third BJTs.

A transimpedance amplifier is provided for converting a current between its two input terminals to a voltage over its two output terminals comprising a high-speed level shifter configured for creating a difference in input DC voltage and for being transparent for alternating voltages, an input biasing network configured for reverse biasing a photodiode connected to at least one of the input terminals and transparent for a feedback signal from the feedback network which is differentially and DC-coupled with the output terminals of the voltage amplifier and outputs of the feedback network are differentially and DC-coupled with the input biasing network of which outputs are coupled with inputs of the level shifter which is differentially and DC-coupled with input terminals of the voltage amplifier.

Some aspects of the disclosure provide for a circuit. In an example, the circuit includes an amplifier, a first transistor network, a second transistor network, a first resistor, a second resistor, and a third resistor. The amplifier has first and second inputs and first, second, third, and fourth outputs. The first transistor network is coupled to the first output of the amplifier and the second output of the amplifier. The second transistor network is coupled to the third output of the amplifier and the fourth output of the amplifier. The first resistor is coupled between the first transistor network and the second transistor network. The second resistor is coupled between the first transistor network and the first input of the amplifier. The third resistor is coupled between the second transistor network and the second input of the amplifier.

Some aspects of the disclosure provide for a circuit. In an example, the circuit includes an amplifier, a first transistor network, a second transistor network, a first resistor, a second resistor, and a third resistor. The amplifier has first and second inputs and first, second, third, and fourth outputs. The first transistor network is coupled to the first output of the amplifier and the second output of the amplifier. The second transistor network is coupled to the third output of the amplifier and the fourth output of the amplifier. The first resistor is coupled between the first transistor network and the second transistor network. The second resistor is coupled between the first transistor network and the first input of the amplifier. The third resistor is coupled between the second transistor network and the second input of the amplifier.

A bandgap reference circuit includes first through fourth bipolar junction transistors (BJTs). The base and collector of the first BJT are shorted together. The second BJT is coupled to the first BJT via a first resistor. The base of the third BJT is coupled to the base of the first BJT. The base and collector of the fourth BJT are coupled together and also are coupled to the base of the second BJT. A second resistor is coupled to the fourth emitter of the fourth BJT. A third resistor is coupled to the second resistor and to the emitter of the second BJT. An operational amplifier has a first input coupled to the first resistor and the collector of the second BJT, a second input coupled to the emitter of the third BJT and the collector of the fourth BJT, and an output coupled to the collectors of the first and third BJTs.

A semiconductor circuit comprising an input block having a first chopper providing a chopped voltage signal, a first transconductance converting said chopped voltage signal into a chopped current signal, a second chopper providing a demodulated current signal, a current integrator having an integrating capacitor providing a continuous-time signal, a first feedback path comprising: a sample-and-hold block and a first feedback block, the first feedback path providing a proportional feedback signal upstream of the current integrator. The amplification factor is at least 2. Charge stored on the integrating capacitor at the beginning of a sample period is linearly removed during one single sampling period. Each chopper operates at a chopping frequency. The sample-and-hold-block operates at a sampling frequency equal to an integer times the chopping frequency.