A differential amplifier circuit includes: a control current source supplying a control current; paired bipolar transistors; an a variable resistance circuit including: a series circuit of a first resistor and a second resistor having an identical resistance, the series circuit electrically connected between a first terminal and a second terminal of the variable resistance circuit; a first field effect transistor (FET) having a source and a drain being electrically connected to emitters of the paired bipolar transistors, respectively; and a second FET having a drain, a gate being electrically connected to the drain thereof, the gate of the first FET, and a control terminal of variable resistance circuit, a source being electrically connected to a connection node between the first resistor and the second resistor, wherein the control current source adjusts the control current to allow transconductance of the second FET to be kept constant.

Modern modulator drivers must be capable of delivering a large output voltage into a tens of ohms modulator, while minimizing the amount of distortion added by the driver. The driver should deliver the output voltage without exceeding a maximum distortion while minimizing the DC power consumption. Accordingly, a modulator driver includes a final stage amplifier with auxiliary transistors that turn on when the conventional differential pair of transistors approaches their maximum voltage of the linear region of their transfer function, thereby providing a more linear transfer function, in particular at large input voltages.

The disclosure provides an amplifier. The amplifier includes a first transistor that receives a first input and generates a first load current. A first output node is coupled to a power supply through a first load resistor. The first load resistor receives the first load current. A first capacitor network is coupled to the first output node and draws a first capacitive current from the first output node. A first current buffer is coupled between the first output node and the first transistor. A current through the first current buffer is a summation of the first load current and the first capacitive current.

A circuit comprises: a circuit input; a circuit output; at least one passive feedback loop coupled between the circuit output and the circuit input; an active element, coupled in a feed-forward path of the circuit between the circuit input and the circuit output and configured to drive the at least one feedback loop in order to establish a function of the circuit, wherein the feed-forward path of the circuit comprises a second node (Vx) and a first node which are internal nodes of the active element and which are coupled between the circuit input and the circuit output, wherein the first node is configured to have a first voltage, the first voltage being a function of the circuit output, wherein the active element comprises a first voltage drop element coupled between the second node (Vx) and the first node.

The disclosure provides an amplifier. The amplifier includes a first transistor that receives a first input and generates a first load current. A first output node is coupled to a power supply through a first load resistor. The first load resistor receives the first load current. A first capacitor network is coupled to the first output node and draws a first capacitive current from the first output node. A first current buffer is coupled between the first output node and the first transistor. A current through the first current buffer is a summation of the first load current and the first capacitive current.

The disclosure provides an amplifier. The amplifier includes a first transistor that receives a first input and generates a first load current. A first output node is coupled to a power supply through a first load resistor. The first load resistor receives the first load current. A first capacitor network is coupled to the first output node and draws a first capacitive current from the first output node. A first current buffer is coupled between the first output node and the first transistor. A current through the first current buffer is a summation of the first load current and the first capacitive current.

A semiconductor amplifier circuit comprising an input block adapted for receiving a voltage signal to be amplified, an integrator circuit having an integrating capacitor providing a continuous-time signal representative for the integral of the voltage 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 larger than 1 for a predefined frequency range. Charge stored on the integrating capacitor at the beginning of a sample period is linearly removed during one single sampling period in such a way that the absolute value of the charge is smaller at the end of the sampling period than at the beginning of the sample period when the voltage signal to be amplified is equal to zero.

An equalizer, in at least some embodiments, comprises an amplifier configured to produce an amplified voltage signal that is a function of an ambient temperature affecting the equalizer. The equalizer also includes a linear equalizer stage coupled to the amplifier and comprising a transistor having a resistance controlled by the amplified voltage signal. The linear equalizer stage is configured to produce a voltage output signal having a gain that is dependent on the transistor resistance and on a frequency of the amplified voltage signal.

The disclosure provides an amplifier. The amplifier includes a first transistor that receives a first input. A second transistor receives a second input. A plurality of impedance networks is coupled between the first transistor and the second transistor. At least one impedance network of the plurality of impedance networks includes a first impedance path and a second impedance path. The first impedance path is activated during single ended operation, and the second impedance path is activated during differential operation.

A circuit comprises: a circuit input; a circuit output; at least one passive feedback loop coupled between the circuit output and the circuit input; an active element, coupled in a feed-forward path of the circuit between the circuit input and the circuit output and configured to drive the at least one feedback loop in order to establish a function of the circuit, wherein the feed-forward path of the circuit comprises a second node (Vx) and a first node which are internal nodes of the active element and which are coupled between the circuit input and the circuit output, wherein the first node is configured to have a first voltage, the first voltage being a function of the circuit output, wherein the active element comprises a first voltage drop element coupled between the second node (Vx) and the first node.