This envelope-detecting circuit comprises: a first multiplier able to multiply a first example of a signal received on an input port by itself, a modifier able to modify the amplitude of the power spectrum, of a second example of the signal received on the input port, at the frequency f.sub.c without modifying the amplitude of this power spectrum in a useful frequency band, a second multiplier able to multiply the modified signal by itself, a subtractor able to subtract from each other the signals delivered by the multipliers, a filter able to remove frequency components higher than or equal to 2f.sub.c in a signal obtained from the signal delivered by the subtractor, this filter being able to deliver the result of this filtering on an output connected to an output port of the envelope-detecting circuit.

This envelope-detecting circuit comprises: a first multiplier able to multiply a first example of a signal received on an input port by itself, a modifier able to modify the amplitude of the power spectrum, of a second example of the signal received on the input port, at the frequency f.sub.c without modifying the amplitude of this power spectrum in a useful frequency band, a second multiplier able to multiply the modified signal by itself, a subtractor able to subtract from each other the signals delivered by the multipliers, a filter able to remove frequency components higher than or equal to 2f.sub.c in a signal obtained from the signal delivered by the subtractor, this filter being able to deliver the result of this filtering on an output connected to an output port of the envelope-detecting circuit.

An electronic envelope detection circuit includes an input signal detecting circuit having at least one MOS transistor configured to receive a radiofrequency input signal and to deliver an internal signal on the basis of the input signal. The biasing point of the at least one transistor is controlled by the input signal and a control signal. A processing circuit that is coupled to the input signal detecting circuit is configured to deliver a low-frequency output signal on the basis of the internal signal and further deliver the control signal on the basis of the output signal. In operation, the value of the control signal decreases when the average power of the input signal increases, and vice versa.

An electronic envelope detection circuit includes an input signal detecting circuit having at least one MOS transistor configured to receive a radiofrequency input signal and to deliver an internal signal on the basis of the input signal. The biasing point of the at least one transistor is controlled by the input signal and a control signal. A processing circuit that is coupled to the input signal detecting circuit is configured to deliver a low-frequency output signal on the basis of the internal signal and further deliver the control signal on the basis of the output signal. In operation, the value of the control signal decreases when the average power of the input signal increases, and vice versa.

A detector circuit includes: a squaring circuit configured to receive an output of a power amplifier of a radio transmitter and to produce an output current, the output of the power amplifier including: a desired tone; a local oscillator leakage tone; and an image tone, and the output current of the squaring circuit including: a direct current (DC) component including a function of the desired tone and an alternating current (AC) component; and a DC current absorber electrically connected to an output terminal of the squaring circuit, the DC current absorber being configured to filter out the DC component of the output current of the squaring circuit to produce a filtered output of the squaring circuit, the filtered output including the AC component including functions of the local oscillator leakage tone and the image tone.

This envelope-detecting circuit comprises: a first multiplier able to multiply a first example of a signal received on an input port by itself, a modifier able to modify the amplitude of the power spectrum, of a second example of the signal received on the input port, at the frequency f.sub.c without modifying the amplitude of this power spectrum in a useful frequency band, a second multiplier able to multiply the modified signal by itself, a subtractor able to subtract from each other the signals delivered by the multipliers, a filter able to remove frequency components higher than or equal to 2f.sub.c in a signal obtained from the signal delivered by the subtractor, this filter being able to deliver the result of this filtering on an output connected to an output port of the envelope-detecting circuit.

This envelope-detecting circuit comprises: a first multiplier able to multiply a first example of a signal received on an input port by itself, a modifier able to modify the amplitude of the power spectrum, of a second example of the signal received on the input port, at the frequency f.sub.c without modifying the amplitude of this power spectrum in a useful frequency band, a second multiplier able to multiply the modified signal by itself, a subtractor able to subtract from each other the signals delivered by the multipliers, a filter able to remove frequency components higher than or equal to 2f.sub.c in a signal obtained from the signal delivered by the subtractor, this filter being able to deliver the result of this filtering on an output connected to an output port of the envelope-detecting circuit.

A regenerative selective logarithmic detector amplifier (LDA) can have integrated FM demodulation capabilities. It can receive a wired or wireless FM modulated signal and amplify or demodulate it with high sensitivity, high skirt ratio and minimized noise when compared to the prior art. When used in conjunction with other circuits such as a PLL or mixer, it can improve interference rejection and frequency selectivity and be locked on a precise channel in frequency and phase. The LDA produces intermittent oscillations that are self-quenched when reaching a given threshold. It also embeds the circuitry to perform direct FM discrimination. FM demodulation process is completed by a simple analog or digital frequency to voltage converter. This plus the fact that the instantaneous regeneration gain is low-medium permit to detect signals of small amplitudes buried in the noise.

A regenerative selective logarithmic detector amplifier (LDA) can have integrated FM demodulation capabilities. It can receive a wired or wireless FM modulated signal and amplify or demodulate it with high sensitivity, high skirt ratio and minimized noise when compared to the prior art. When used in conjunction with other circuits such as a PLL or mixer, it can improve interference rejection and frequency selectivity and be locked on a precise channel in frequency and phase. The LDA produces intermittent oscillations that are self-quenched when reaching a given threshold. It also embeds the circuitry to perform direct FM discrimination. FM demodulation process is completed by a simple analog or digital frequency to voltage converter. This plus the fact that the instantaneous regeneration gain is low-medium permit to detect signals of small amplitudes buried in the noise.

An electronic envelope detection circuit includes an input signal detecting circuit having at least one MOS transistor configured to receive a radiofrequency input signal and to deliver an internal signal on the basis of the input signal. The biasing point of the at least one transistor is controlled by the input signal and a control signal. A processing circuit that is coupled to the input signal detecting circuit is configured to deliver a low-frequency output signal on the basis of the internal signal and further deliver the control signal on the basis of the output signal. In operation, the value of the control signal decreases when the average power of the input signal increases, and vice versa.