A communication system includes a demodulator configured to demodulate a modulated signal responsive to a first carrier signal. The demodulator includes a filter and a gain adjusting circuit. The filter is configured to generate a filtered first signal based on a first signal. The first signal is a product of the first carrier signal and the modulated signal. The filter has a gain adjusted based on a set of control signals. The gain adjusting circuit is coupled to the filter, and is configured to generate the set of control signals based on at least a voltage of the filtered first signal. The gain adjusting circuit includes a first peak detector coupled to the filter. The first peak detector is configured to output a peak value of the voltage of the filtered first signal.

A communication system includes a transmitter configured to transmit a modulated signal, a transmission line configured to carry the modulated signal, and a receiver coupled to the transmitter by the transmission line, and configured to receive the modulated signal. The transmitter includes a modulator configured to generate the modulated signal responsive to a data signal and a carrier signal. The receiver includes a demodulator configured to demodulate the modulated signal responsive to a first carrier signal. The demodulator includes a filter and a gain adjusting circuit configured to adjust a gain of the filter, and to generate the set of control signals based on a voltage of the filtered first signal and a voltage of the first signal. The gain adjusting circuit includes a first peak detector coupled to the filter, and configured to detect a peak value of the voltage of the filtered first signal.

A hybrid automatic level control (ALC) system for controlling analog outputs. Within the ALC, a feedback loop passes from an analog circuit to a digital circuit and may provide the level of the analog output to the digital circuit. The digital circuit may use lookup tables to model the responses of analog devices but without associated errors and complications of the analog domain. Some examples of the modeled response include linear frequency responses of analog diodes and frequency responses of analog filters. Based on the received feedback and using the lookup tables modeling the responses, the digital circuit may drive a digital-to-analog converter interfacing the analog circuit to control the level of the analog output.

A packet-based radio receiver (10) comprises an automatic gain control system (17) and a signal-level detector (18, 19, 20) for monitoring an analogue signal derived from radio signals received by the radio receiver. The signal-level detector (18, 19, 20) comprises a binary memory cell (22, 24) and a monitoring system. The monitoring system comprises a comparator (21, 23) arranged to receive a reference voltage at a first input and the analogue signal at a second input. The monitoring system is arranged to (i) continuously monitor the voltage of the analogue signal, (ii) detect when the monitored signal exceeds the reference voltage, and (iii) store a predetermined binary value in the memory cell (22, 24) in response to such a detection. The automatic gain control system (17) is arranged to control the gain of a variable-gain component (12, 13, 14) of the radio receiver in dependence on the contents of the binary memory cell (22, 24).

An automatic gain control (AGC) circuit and method are provided herein to control the gain, and the gain step size, of an amplifier circuit based on a duration of a detected overload condition. According to one embodiment, a method of gain control may include comparing a received signal to a threshold value, detecting an overload condition if the received signal exceeds the threshold value, detecting a duration of the overload condition, and controlling the gain, and the gain step size, of the amplifier circuit based on the detected duration of the overload condition.

Examples provide a method of performing automatic gain control (AGC) in a wireless receiver, the method including computing, by an energy detection (ED) circuit, a variance in an output signal of an analog-to-digital converter (ADC), and activating, by the ED circuit, an AGC circuit to adjust a gain of at least one component in a radio frequency integrated chip (RFIC) in response to the variance exceeding a threshold. Examples also provide for a wireless receiver that implements such a method.

Disclosed herein is a DC offset cancellation circuit. The DC offset cancellation circuit includes a DC feedback unit configured to vary a DC feedback (DCFB) bandwidth to add at least one mid-bandwidth to the DCFB bandwidth and to provide a delay time in each case in order to reduce the DC droop error that occurs in switching from the high bandwidth (BW) to the mid-BW or from the mid-BW mode to the low BW mode, such that stable settling is ensured.

An apparatus includes an input terminal to receive a radio frequency (RF) signal and to communicate the RF signal to a low noise amplifier (LNA) via an input signal path, and a capacitor attenuator coupled to the input terminal to attenuate the RF signal by a controllable amount and having a first portion controllable to include a used part configured on the input signal path and an unused part coupled between the input signal path and an AC reference node, and a second portion coupled between the LNA and the AC reference node.

A radio frequency receiver and an automatic gain control method of the radio frequency receiver is presented. The radio frequency receiver includes an automatic gain control apparatus, a radio frequency component, and an analog to digital converter, where the automatic gain control apparatus further includes: an intensity calculator configured to calculate a relationship between an intensity representation parameter of digital data and a preset intensity threshold within a preset calculation time; and an automatic gain controller configured to compare the relationship calculated by the intensity calculator with a preset relationship threshold, and adjust a gain of the radio frequency component on radio frequency data according to a comparison result, so that an amplitude of the radio frequency data obtained after the gain adjustment is within a receiving range of the analog to digital converter.

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.