A frequency modulated continuous wave (FMCW) light detection and ranging (LIDAR) system includes an automatic gain control (AGC) unit to reduce the dynamic range of the signal to be processed. The system detects a return beam of a light signal transmitted to a target, having a first dynamic range in a time domain. The AGC unit can measure a power of the return beam, and apply variable gain in the time domain to reduce a dynamic range of the return beam to a lower dynamic. An analog to digital converter (ADC) generates a digital signal based on the return beam. A processor can perform time domain processing on the digital signal, convert the digital signal from the time domain to a frequency domain, and perform frequency domain processing on the digital signal in the frequency domain.

According to one embodiment, a semiconductor circuit includes a first transimpedance amplifier and a second transimpedance amplifier. The first transimpedance amplifier is configured to convert an input current to a first output voltage and output the first output voltage from a first output terminal when a reference voltage is supplied to a first input terminal and the input current is supplied to a second input terminal. The second transimpedance amplifier has a circuit configuration similar to a circuit configuration of the first transimpedance amplifier. The second transimpedance amplifier is configured to output a second output voltage from a second output terminal when the reference voltage is supplied to a third input terminal.

In a signal processing device, a branch section generates, from an input signal which is a current signal, a plurality of branch signals that are proportional to the input signal and have different signal intensities, and supplies the plurality of branch signals to respective different individual paths. A selection section selects one of the plurality of individual paths and outputs a signal supplied through the selected individual path. A determination section determines whether in each of the plurality of individual paths, a magnitude of a signal supplied to the selection section is in a preset allowable range. A control section causes the selection section to select the individual path having a highest gain among the individual paths in which the magnitude of the signal is determined by the determination section to be in the allowable range.

In a signal processing device, a branch section generates, from an input signal which is a current signal, a plurality of branch signals that are proportional to the input signal and have different signal intensities, and supplies the plurality of branch signals to respective different individual paths. A selection section selects one of the plurality of individual paths and outputs a signal supplied through the selected individual path. A determination section determines whether in each of the plurality of individual paths, a magnitude of a signal supplied to the selection section is in a preset allowable range. A control section causes the selection section to select the individual path having a highest gain among the individual paths in which the magnitude of the signal is determined by the determination section to be in the allowable range.

A transimpedance amplifier includes a feedback circuit that generates a bypass current in accordance with a charging voltage of a capacitor based on a difference between a voltage signal and a reference voltage signal, a differential amplifier circuit that generates a differential signal in accordance with the difference between the voltage signal and the reference voltage signal, and a detector circuit that resets the charging voltage of the capacitor in response to a detection of end of a burst optical signal. The feedback circuit detects start of the burst optical signal based on the charging voltage, maintains a time constant at a first time constant for a predetermined period from the detection of the start of the burst optical signal, and, upon an elapse of the predetermined period, switches the time constant from the first time constant to a second time constant larger than the first time constant.

A transimpedance amplifier includes a feedback circuit that generates a bypass current in accordance with a charging voltage of a capacitor based on a difference between a voltage signal and a reference voltage signal, a differential amplifier circuit that generates a differential signal in accordance with the difference between the voltage signal and the reference voltage signal, and a detector circuit that resets the charging voltage of the capacitor in response to a detection of end of a burst optical signal. The feedback circuit detects start of the burst optical signal based on the charging voltage, maintains a time constant at a first time constant for a predetermined period from the detection of the start of the burst optical signal, and, upon an elapse of the predetermined period, switches the time constant from the first time constant to a second time constant larger than the first time constant.

A current to digital converter circuit has an integrator amplifier with an input adapted to receive a current signal and an output adapted to provide a voltage signal as a function of an integration of the current signal, a quantizer circuit with an input which is coupled to the output of the integrator amplifier and with an output adapted to provide a binary result signal as a function of a comparison of the voltage signal with at least a first reference voltage signal, a digital-to-analog converter circuit which is coupled in a switchable manner as a function of the binary result signal to the input of the integrator amplifier, and a controlled current source which is coupled to the output of the integrator amplifier via a first switch which is controlled as a function of the binary result signal such that an auxiliary current is supplied to the output of the integrator amplifier.

A differential transimpedance amplifier (DTIA) includes a first input, a second input, a first output, and a second output. The DTIA also includes a first inverter and a second inverter connected in series to the first input. The DTIA further includes a third inverter and a fourth inverter connected in series to the second input. The first inverter and the fourth inverter receive a first supply voltage from a first voltage regulator. The second inverter and the third inverter receive a second supply voltage from a second voltage regulator. The first supply voltage changes (i) based on a difference between voltages on the first output and the second output and (ii) while the second supply voltage remains fixed.

Apparatuses include (among other components) a first gain device connected to receive an initial voltage, a second gain device in series with the first gain device and connected to receive output of the first gain device, differential gain devices connected to receive outputs from the first gain device and the second gain device (the differential gain devices provide opposite voltage outputs from the apparatus) and high-frequency compensation feed-forward paths connected to the first gain device and the second gain device.

The present disclosure provides for process and temperature compensation in a transimpedance amplifier (TIA) using a dual replica via monitoring an output of a first TIA (transimpedance amplifier) and a second TIA; configuring a first gain level of the first TIA based on a feedback resistance and a reference current applied at an input to the first TIA; configuring a second gain level of the second TIA and a third TIA based on a control voltage; and amplifying a received electrical current to generate an output voltage using the third TIA according to the second gain level. In some embodiments, one or both of the second TIA and the third TIA include a configurable feedback impedance used in compensating for changes in the second gain level due to a temperature of the respective second or third TIA via the configurable feedback impedance of the respective second or third TIA.