Provided is a spectrometer. The spectrometer includes: a light source part configured to emit light of a plurality of wavelengths onto an object; a detector configured to detect an optical signal of each of the plurality of wavelengths as reflected from the object; a controller configured to set an amplification gain for each of the plurality of wavelengths according to photoreaction properties of the object; and an amplifier configured to amplify an output signal of the detector by using the set amplification gain.

A HDR CTIA pixel which provides automatic gain selection, and spatial and temporal coherence. The pixel comprises an input node for connection to a photocurrent, and an output node. The pixel includes a CTIA which comprises a high gain integration capacitor and a first reset switch connected between the input and output nodes, a low gain integration capacitor connected between the input node and a first node, a second reset switch connected between the first node and the output node, and a first FET connected across the second reset switch. In operation, the first FET is off during the reset phase, and is conditionally turned on during or after the integration phase. The CTIA also includes an amplifier having an inverting input connected to the input node and an output connected to the output node. The pixel can be operated in static low-gain control and dynamic low-gain control modes.

An apparatus is described which uses directly modulated InGaN Light-Emitting Diodes (LEDs) or InGaN lasers as the transmitters for an underwater data-communication device. The receiver uses automatic gain control to facilitate performance of the apparatus over a wide-range of distances and water turbidities.

Described is an apparatus which comprises: an amplifier to receive a reference voltage; and calibration logic which is operable to receive a first voltage and to provide the reference voltage to the amplifier, wherein the calibration logic is operable to generate a look-up table (LUT) that maps the first voltage to a drive current.

Introduced here are techniques for implementing a comparator-based LIDAR system with improved components, such as an improved high-speed comparator circuit, to acquire depth information from the surroundings of an unmanned moving object (e.g., a UAV). In various embodiments, the LIDAR system includes an amplifier module with different configurations of anti-saturation circuitry. The LIDAR system may further include various feedback control mechanisms for noise interference reduction and timing measurement compensation including, for example, dynamic gain adjustment of the photodetector module, and/or dynamic adjustment of comparators' thresholds. Among other components, the disclosed comparator circuit can provide the LIDAR system with a wide dynamic range, preventing large signal amplification saturation while also providing sufficient magnification of small signals.

A passive bias temperature compensation module for silicon photomultiplier, avalanche photodiodes and similar photodetectors that possess a moderately linear temperature coefficient of gain and that may be compensated by varying an applied bias voltage. The module includes an electrical circuit and a method for determining component values to provide a constant voltage source to stabilize the gain of one or more photodetector devices. A temperature sensor in the module is held in close thermal contact with the photodetector and a filter capacitor is electrically close to the photodetector. The module is based on the concept of temperature sensitive voltage division which is applicable to situations in which large numbers of photodetectors must be gain-compensated for temperature variations over a wide range while maintaining excellent gain matching. The passive bias temperature compensation method enables multiple photodetectors to share a single constant voltage supply without loss of matching performance.

An automatic gain control circuit for controlling an LNA for inputting signals carrying packets, the automatic gain control circuit can perform a background calibration in the non-preamble time region of a first packet for pre-determining a gain adjustment to the LNA before the next preamble of a second packet arrives, so that the gain of the LNA can be adjusted immediately according to the pre-determined gain adjustment when the next preamble of the second packet arrives.

An amplifier circuit includes: an amplifier configured to receive at least one input signal and generate an output voltage in response to the at least one input signal and a gain control voltage; a voltage detector configured to generate a detector voltage based on the output voltage; a gain control summation circuit configured to generate an error signal by subtracting the detector voltage from a reference voltage; a loop filter configured to generate the gain control voltage based on the error signal and adjust the loop bandwidth in response to a loop filter adjust signal; and an analog automatic gain control bandwidth controller configured to monitor the detector voltage and the gain control voltage, to provide the reference voltage and the loop filter adjust signal, and to control a loop bandwidth of the output signal.

A variable resistance element is connected between a first input terminal of a first amplifier and a second input terminal of a second amplifier, and has a resistance value between the first input terminal and the second input terminal that is varied according to an amplitude value of a first voltage signal or an amplitude value or a differential voltage signal. A variable current source is connected between the first input terminal and a ground, and controls a current value of a current flowing to the ground from the first input terminal according to a value of an offset of the differential voltage signal. A bias voltage having the same value as that of a bias voltage that is applied to the first input terminal is applied to the second input terminal.

Some embodiments described herein are directed to a photo sensor and a method of operating a photo sensor. In an embodiment, a photo sensor comprises a photo diode, a filter circuit, and an output circuit. The filter circuit has an input node configured to be electrically coupled to an output node of the photo diode, and has an output node. The filter circuit has an adjustable gain, and the adjustable gain is adjustable based on a signal output from the filter circuit. The output circuit has an input node configured to be electrically coupled to the output node of the filter circuit.