A variable gain amplifier (1) includes: a signal transmission circuit (10, 20) including amplifying transistor units (11.sub.1 to 11.sub.N, and 21.sub.1 to 21.sub.N) connected in parallel between a signal input port (2P, 2N) and a signal output port (3P, 3N); a load circuit (40) connected between a supply line of power supply voltage (VDD) and an output end of the signal transmission circuit (10, 20); a signal short circuit (30) including a short-circuit transistor unit (31) connected between the supply line of the power supply voltage (VDD) and an input end of the signal transmission circuit (10, 20), a constant-current source circuit (42), and a transistor control circuit (46). The transistor control circuit (46) selects transistor units to be turned on, from among the amplifying transistor units (11.sub.1 to 11.sub.N, and 21.sub.1 to 21.sub.N) and the short-circuit transistor unit (31), and supplies control voltages for turning on the selected transistor units.

Each input channel adjusts a level of an audio signal by individual first parameters and outputs the level-adjusted audio signals to individual output routes that include bus channels. Each bus channel mixes the level-adjusted audio signals and processes the mixed audio signal by a second parameter to output to a main output. A preview channel adjusts a level of the audio signal of each of input channels by a third parameter, mixes the level-adjusted audio signals of the input channels and processes the mixed audio signal by a fourth parameter to output to a monitor output. In response to a preview instruction, the first parameter of the input channel is copied as the third parameter, and the second parameter of the bus channel is copied as the fourth parameter of the preview channel. In response to an adjustment instruction, the third or fourth parameter of the preview channel is changed.

According to one embodiment, a compact low-power receiver comprises first and second analog circuits connected by a digitally controlled interface circuit. The first analog circuit has a first direct-current (DC) offset and a first common mode voltage at an output, and the second analog circuit has a second DC offset and a second common mode voltage at an input. The digitally controlled interface circuit connects the output to the input, and is configured to match the first and second DC offsets and to match the first and second common mode voltages. In one embodiment, the first analog circuit is a variable gain control transimpedance amplifier (TIA) implemented using a current mode buffer, the second analog circuit is a second-order adjustable low-pass filter, whereby a three-pole adjustable low-pass filter in the compact low-power receiver is effectively produced.

An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.

A coaxial speaker tweeter temperature protection method, a coaxial speaker tweeter temperature protection system, and a computer-readable storage medium are provided. The coaxial speaker tweeter temperature protection method is applied to a coaxial speaker including a tweeter and a woofer, including steps of acquiring a woofer real-time temperature, performing calculation on the woofer real-time temperature and a pre-processed input signal through a tweeter temperature prediction algorithm to predict a tweeter real-time temperature in a current state, where the pre-processed input signal is a signal acquired after processing a sound effect algorithm on an input audio signal, etc. Compared with the related art, the coaxial speaker tweeter temperature protection method, the coaxial speaker tweeter temperature protection system, the electronic device, and the computer-readable storage medium provide better temperature protection for the tweeter, reliability of which is better.

The present invention provides a transducer protection system and method. A transducer module at least comprises a transducer, and a signal source is used for generating a first signal; a protection module is used for predicting an actual displacement and/or temperature of the transducer according to the first signal, an amplification factor of the power amplifier and built-in transducer parameters to generate a prediction result, comparing the prediction result with a preset value to generate an analysis result, and regulating the first signal to form a second signal according to the analysis result; a power amplifier is used for receiving the second signal, and performing power amplification on the second signal to form a driving signal; and the transducer module is used for receiving the driving signal, and at least one transducer in the transducer module can work according to the driving signal.

An active device and circuits utilised therewith are disclosed. In an aspect the active device comprises an n-type transistor having a drain, gate and bulk and a p-type transistor having a drain, gate and bulk. The n-type transistor and the p-type transistor include a common source. The device includes a first capacitor coupled between the gate of the n-type transistor and the gale of the p-type transistor, a second capacitor coupled between the drain of the n-type transistor and the drain of p-type transistor and a third capacitor coupled between the bulk of the n-type transistor and the bulk of p-type transistor. The active device has a high breakdown voltage, is memory less and traps even harmonic signals.

Each input channel adjusts a level of an audio signal by individual first parameters and outputs the level-adjusted audio signals to individual output routes that include bus channels. Each bus channel mixes the level-adjusted audio signals and processes the mixed audio signal by a second parameter to output to a main output. A preview channel adjusts a level of the audio signal of each of input channels by a third parameter, mixes the level-adjusted audio signals of the input channels and processes the mixed audio signal by a fourth parameter to output to a monitor output. In response to a preview instruction, the first parameter of the input channel is copied as the third parameter, and the second parameter of the bus channel is copied as the fourth parameter of the preview channel. In response to an adjustment instruction, the third or fourth parameter of the preview channel is changed.

A transmission module includes n oscillator modules and a phase command signal generator. Each of the oscillator modules includes a voltage controlled oscillator and an amplification circuit. The voltage controlled oscillators output transmission high-frequency signals having the same frequency and synchronized among the n oscillator modules by synchronous control based on a common reference signal. The amplification circuits each perform power amplification for the transmission high-frequency signal from a corresponding one of the voltage controlled oscillators and output the resultant signal. Phases of the transmission high-frequency signals synchronized among the n oscillator modules and output from the voltage controlled oscillators are separately controlled according to respective n phase command signals from the phase command signal generator.

A variable-gain power amplifying technique includes generating, with a network of one or more reactive components included in an oscillator, a first oscillating signal, and outputting, via one or more taps included in the network of the reactive components, a second oscillating signal. The second oscillating signal has a magnitude that is proportional to and less than the first oscillating signal. The power amplifying technique further includes selecting one of the first and second oscillating signals to use for generating a power-amplified output signal, and amplifying the selected one of the first and second oscillating signals to generate the power-amplified output signal.