A method for dynamic sizing of a blocker margin by a receiver automatic gain control (AGC) is described. The method includes measuring a wanted signal level and a blocker signal level. The method also includes adjusting a linear target for the wanted signal level at the output of an analog-to-digital converter (ADC) of the receiver based on the blocker signal level. The linear target is adjusted to optimize a wanted signal signal-to-noise ratio (SNR) and the blocker margin. The method further includes adjusting a receiver front-end gain based on the adjusted linear target.

An amplifier, a circuit, and an optical communication system are provided. The disclosed amplifier may include a first transistor receiving a first portion of an input signal received at the amplifier, a second transistor receiving a second portion of the input signal, an automatic gain control signal that is dynamically adjustable in response to variations in an output of the amplifier, and a varactor that has its capacitance adjusted by changes in the automatic gain control signal and, as a result, adjusts a position of a pole in a transfer function of the amplifier.

A digitally-controlled transimpedance amplifier (TIA) circuit is provided in which a plurality of feedback loops are digitally controlled, including, but not limited to, the DC offset cancellation loop, the variable gain control loop, and the TIA feedback impedance adjustment loop. The digitally-controlled TIA circuit includes digital loop-control circuitry that consumes less area on the TIA IC chip than the analog circuitry traditionally used to perform the feedback loop control in the analog domain. In addition, because digital logic continues to shrink as IC processes continue to evolve, the size of the IC chip packages will further decrease over time, leading to a smaller footprint in systems in which they are employed. The digital loop control circuitry is also capable of independently varying the gains of multiple gain stages of the variable gain control circuit to provide better control over the gain stages and better overall performance of the TIA circuit.

According to one embodiment, an amplification circuit includes an amplifier having a gain based on a gain control signal and amplifying an input signal by the gain, and a control portion outputting the gain control signal for increasing the gain after decreasing the gain based on an amplitude of the input signal, when the amplitude of the input signal is detected.

This disclosure relates to the field of amplifiers for multi-level optical communication and more particularly to techniques for trans-impedance amplifiers (TIA) with gain control. The claimed embodiments address the problem of implementing a low cost TIA that exhibits high linearity, low noise, low power, and wide bandwidth. More specifically, some claims are directed to approaches for providing TIA gain control using a plurality of inverter-based replica gain control cells controlled by a feedback loop to manage the current into the amplifying output stage and thereby the TIA output voltage.

An imaging system includes an array of photodetectors and electronic circuitry associated with the photodetectors to read intensity values from the photodetectors. The electronic circuitry can include an integrator with an integrator capacitor having a nominal capacitance, wherein a gain of the electronic circuitry associated with a photodetector can depend at least in part on the actual capacitance of the integrator capacitor, the actual capacitance differing from the nominal capacitance. The imaging system can be configured to determine a gain factor that depends at least in part on the actual capacitance and/or a signal voltage input to the integrator. The imaging system can be configured to apply the gain factor based at least in part on the actual capacitance of the integrator capacitor calculated. The imaging system can be a thermal imaging system and may include an infrared camera core.

A peak detector using a charge pump is provided. The peak detector includes a differential amplifier configured to receive an input signal to be detected through an input node and amplify the received signal; a current control logic configured to create two or more current control signals by comparing a signal output from the differential amplifier with two or more reference voltages; a mirror current source portion comprising two or more mirror current sources configured to be driven respectively by the current control signals from the current control logic; a capacitor configured to be charged or discharged by currents output from the mirror current sources; and a reset circuit configured to reset a voltage of the capacitor.

Apparatus and methods for preventing overshoot for a high-to-low input current transient of a logarithmic transimpedance amplifier are disclosed. In certain embodiments, an amplifier system includes a logarithmic transimpedance amplifier having an input that receives an input current signal, and a current pulse injection circuit that injects a current pulse into the input of the logarithmic transimpedance amplifier in response to detecting a transition of the input current signal from a high current value to a low current value.

This application relates to transimpedance amplifier (TIA) apparatus, in particular to a TIA apparatus suitable for receiving data using burst mode communication. The apparatus has a transimpedance amplifier configured to generate a first voltage based on a current at an input node for an input signal. A controlled voltage source, such as a dummy TIA, generates a second voltage based on a first control current. A controller is configured to collectively control the first control current and a second control current based on an indication of input signal magnitude. The first control current controls the second voltage which may be used as a slicing level. The second control current is subtracted from the current at the input node and can provide a DC restore current.

A signal adjusting circuit and a receiving end circuit using the same are provided. The signal adjusting circuit is adapted to a peak detector, and includes a first amplifier and a first feedback circuit. The first amplifier receives a first input signal, and amplifies the first input signal to output a first output signal. The first feedback circuit is connected between a first input terminal and a first output terminal of the first amplifier, and is configured to determine a first gain of the first output signal. The peak detector is connected to a first output node of the first feedback circuit, so as to receive a first detection signal and detect a peak value of the first detection signal. The peak detector has a predetermined power input range, and the first feedback circuit keeps the first detection signal within the predetermined power input range.