A power amplifier includes a transistor, a temperature sensor and a filter. The transistor is used to receive a bias signal and amplify a radio frequency (RF) signal. The temperature sensor is arranged in proximity to the transistor, and is used to detect a temperature of the transistor to provide a voltage signal at a control node accordingly. The filter is coupled to the temperature sensor and is used to filter the voltage signal to generate a filtered voltage. The bias signal is adjusted according to the filtered voltage.

A method of controlling bandwidth and peaking over gain in a variable gain amplifier (VGA) device and structure therefor. The device includes at least three differential transistor pairs configured as a cross-coupled differential amplifier with differential input nodes, differential bias nodes, differential output nodes, a current source node, and two cross-coupling nodes. The cross-coupled differential amplifier includes a load resistor coupled to each of the differential output nodes and one of the cross-coupling nodes, and a load inductor coupled to the each of the cross-coupling nodes and a power supply rail. A current source is electrically coupled to the current source node. The cross-coupling configuration with the load resistance and inductance results in a lower bandwidth and lowered peaking at low gain compared to high gain. Further, the tap point into the inductor can be chosen as another variable to “tune” the bandwidth and peaking in a communication system.

A variable gain amplifier system includes a variable gain amplifier circuit configured to receive an input signal, apply a gain to the input signal, and generate an output signal in accordance with the gain applied to the input signal. The variable gain amplifier circuit is further configured to receive a gain control signal and a bandwidth control signal. A control module is configured to generate the gain control signal to adjust the gain of the variable gain amplifier circuit and generate, separately from the gain control signal, the bandwidth control signal to adjust a bandwidth of the variable gain amplifier circuit by selectively varying an amount of inductance contributed by an inductor circuit of the variable gain amplifier circuit.

A power amplifier includes a transistor, a temperature sensor and a filter. The transistor is used to receive a bias signal and amplify a radio frequency (RF) signal. The temperature sensor is arranged in proximity to the transistor, and is used to detect a temperature of the transistor to provide a voltage signal at a control node accordingly. The filter is coupled to the temperature sensor and is used to filter the voltage signal to generate a filtered voltage. The bias signal is adjusted according to the filtered voltage.

The present invention is directed electrical circuits. According to a specific embodiment, the present invention provides a variable gain amplifier that includes a first switch, which includes drain terminal coupled to an inductor. A second switch is configured in parallel to the inductor, and the resistance value of the second switch is adjustable in response to a control signal. There are other embodiments as well.

Aspects of this disclosure relate to a receiver for a light detection and ranging system. The receiver includes a transimpedance amplifier that is operable in a linear mode for a range of power of light received by the receiver. The receiver can provide information about amplitude of the light outside of the range of power of the light for which the transimpedance amplifier operates in the linear mode. This information can be useful, for example, in identifying an object from which light received by the receiver was reflected.

In optical receivers, extending the transimpedance amplifier's (TIA) dynamic range is a key to increasing the receiver's dynamic range, and therefore increase the channel capacity. Ideally, the TIA requires controllable gain, whereby the receiver can modify the characteristics of the TIA and/or the VGA to process high power incoming signals with a defined maximum distortion, and low power incoming signals with a defined maximum noise. A solution to the problem is to provide TIA's and VGA's with reconfigurable sizes, which are adjustable based on the level of power, e.g. current, generated by the photodetector.

A method of controlling bandwidth and peaking over gain in a variable gain amplifier (VGA) device and structure therefor. The device includes at least three differential transistor pairs configured as a cross-coupled differential amplifier with differential input nodes, differential bias nodes, differential output nodes, a current source node, and two cross-coupling nodes. The cross-coupled differential amplifier includes a load resistor coupled to each of the differential output nodes and one of the cross-coupling nodes, and a load inductor coupled to the each of the cross-coupling nodes and a power supply rail. A current source is electrically coupled to the current source node. The cross-coupling configuration with the load resistance and inductance results in a lower bandwidth and lowered peaking at low gain compared to high gain. Further, the tap point into the inductor can be chosen as another variable to tune the bandwidth and peaking in a communication system.

A power amplifier circuit includes a first transistor that amplifies an RF signal; a bias current source that supplies a bias current to a second terminal of the first transistor through a first current path; and an adjustment circuit that adjusts the bias current in accordance with a variable power-supply voltage supplied from a power-supply terminal. The adjustment circuit includes first to third resistors, and an adjustment transistor including a first terminal connected to the power-supply terminal through the first resistor, a second terminal connected to the bias current source through the second resistor, and a third terminal connected to the first current path through the third resistor. When the variable power-supply voltage is not less than a first voltage and not greater than a third voltage, the adjustment circuit increases a current that flows to the power-supply terminal through a second current path as the variable power-supply voltage decreases.

A method of controlling bandwidth and peaking over gain in a variable gain amplifier (VGA) device and structure therefor. The device includes at least three differential transistor pairs configured as a cross-coupled differential amplifier with differential input nodes, differential bias nodes, differential output nodes, a current source node, and two cross-coupling nodes. The cross-coupled differential amplifier includes a load resistor coupled to each of the differential output nodes and one of the cross-coupling nodes, and a load inductor coupled to the each of the cross-coupling nodes and a power supply rail. A current source is electrically coupled to the current source node. The cross-coupling configuration with the load resistance and inductance results in a lower bandwidth and lowered peaking at low gain compared to high gain. Further, the tap point into the inductor can be chosen as another variable to tune the bandwidth and peaking in a communication system.