An amplitude detector has a phase shifter such as one using an analog differentiator and an adjustable gain stage, or one using a determinable delay, the phase shifter coupled to shift phase of an input signal to the amplitude detection apparatus. The detector also has a first analog multiplier coupled to square the input signal, a second analog multiplier coupled to square output of the phase shifter; and an analog adder coupled to sum outputs of the first and second analog multiplier. An automatic gain control circuit has the amplitude detector coupled to control gain of a controllable amplifier.

A radio frequency module includes: a transmission power amplifier that includes a plurality of amplifying elements that are cascaded; a reception low noise amplifier; and a module board on which the transmission power amplifier and the reception low noise amplifier are mounted. The plurality of amplifying elements include: an amplifying element disposed most downstream; and an amplifying element disposed upstream of the amplifying element, and in a plan view of the module board, a conductive member is physically disposed between the amplifying element and the reception low noise amplifier.

According to one mode of the inventive concept, an amplification device includes a first amplifier configured to amplify an input multi-band signal to a first level, a separating unit configured to separate the multi-band signal having the first level into a first band signal and a second band signal, and a second amplifier configured to amplify the second band signal to a second level.

A bidirectional RF circuit, preferably including a plurality of terminals, a switch, a transistor, a coupler, and a feedback network. The circuit can optionally include a drain matching network, an input matching network, and/or one or more tuning inputs. In some variations, the circuit can optionally include one or more impedance networks, such as an impedance network used in place of the feedback network; in some such variations, the circuit may not include a coupler, switch, and/or input matching network. A method for circuit operation, preferably including operating in an amplifier mode, operating in a rectifier mode, and/or transitioning between operation modes.

A detection calibration circuit includes a first distributor distributing a high frequency input signal, an amplifier amplifying the first high frequency output signal of the first distributor, a second distributor distributing the amplified first high frequency output signal of the first distributor, a reference signal generator outputting a reference signal in accordance with a switchable reference voltage, a switcher selecting a third high frequency output signal of the second distributor or a reference signal of the reference signal generator and outputting the selected signal, a detector detecting the third high frequency output signal of the second distributor or the reference signal of the reference signal generator from the switcher, a sensitivity switcher adjusting a sensitivity for an output signal of the detector, and a calibration control circuit adjusting a detection gain of an input signal of the detector and an input-output sensitivity for an output signal of the detector.

An amplifier circuit includes a continuous-time linear equalizer, an adjustable gain circuit and a filter circuit. The continuous-time linear equalizer includes a first high-pass path, a first low-pass path, a second high-pass path, and a second low-pass path. The first high-pass path is used to increase a gain of a high-frequency part of a first signal source, and the second high-pass path is used to increase a gain of a high-frequency part of a second signal source. The filter circuit is used to amplify and filter the first signal source and the second signal source, and includes a fully-differential operational amplifier, a first filter network, and a second filter network.

A cascadable AGC amplifier in a signal distribution system includes a low noise cascadable amplifier having a through path and a cascadable output. The cascadable amplifier is also configured to provide AGC over a predetermined input power range. The cascadable AGC amplifier can be configured to provide gain or attenuation. When the cascadable AGC amplifier is implemented in a signal distribution system, typically as part of a signal distribution device, an input signal can be gain controlled and supplied to multiple signal paths without distortion due to degradation of signal to noise ratio or distortion due to higher order amplifier products. The distributed signal is not significantly degraded by distortion regardless of the number of cascadable AGC amplifiers connected in series or the position of the cascadable AGC amplifier in the signal distribution system.

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).

A differential comparator has a first input and a second input comprises: first and second transistors arranged as a differential pair connected to the first and second inputs respectively; and a constant current arrangement disposed between said differential pair and a first supply rail;
wherein a first path between the first transistor and the constant current arrangement has a different resistance to a second path between the second transistor and the constant current arrangement.

Also disclosed is a radio receiver employing such a differential comparator.

Techniques are provided for automatic gain control processing to reduce adverse effects associated with clipped samples resulting from conversion of analog signals to digital signals. A methodology according to an embodiment includes identifying a clipped sample of the digital signal, for example by comparison of the digitized sample values to a threshold value associated with a full scale value of the converter. The method also includes applying a window function to portions of the digital signal. The window function is configured to attenuate samples of the digital signal within a region centered on the identified clipped sample. A Hilbert finite impulse response (FIR) filter may be applied to the digital signal prior to applying the window function. Parameters of the window function are selected based on frequency response characteristics of the FIR filter and on signal to noise ratio requirements of an application that receives the windowed digital signal.