A high-frequency signal step attenuator including an amplifying circuit having a transistor element with its base or gate connected to an input terminal to which a high-frequency input signal is supplied, and supplying an amplified output signal of the input signal to an output terminal, a current detector for detecting a current flowing through a current path of collector-emitter or a current path of drain-source of the transistor element to generate an output voltage corresponding to a detected current, a voltage setter for selectively generating output voltages of different levels, and a comparator for comparing the output voltage of the current detector with the output voltage of the voltage setter, and supplying an output signal of a compared result as a feedback signal to the base or gate of the transistor element.
There is described an amplitude-controlled electronic device (1) intended to generate at an output (11; 11a) an alternating output signal (S1; Sosc) of substantially constant amplitude. This electronic device includes a measuring branch (20; 20*; 201) for generating a measuring voltage (Vout) representative of the amplitude of the output signal (S1; Sosc) and means for generating a reference voltage (Vref) including a reference branch (40; 40*; 400) matched with the measuring branch and at the input (A) of which a voltage reference (U0) is selectively switched. A comparator (30; 300) is arranged for comparing the measuring and reference voltages and generating in response a control signal (Sc) which is applied on a control terminal (12) of the electronic device. According to the invention, the matching of the measuring and reference branches allows the sensitivity of the control signal to temperature and manufacturing process variations to be substantially cancelled.
A transmitter circuit and method for transmitting a data signal at a desired transmitter power level. The transmitter circuit includes an attenuator for attenuating the data signal by an attenuation factor. An external amplifier receives the attenuated signal and amplifies the signal to an amplified signal voltage. A storage unit containing a set of calibrated power levels associated to a set of amplifier voltages provides a calibrated power level based on the amplified signal voltage. A controller is configured to modify the attenuation factor of the attenuator in response to the difference between the calibrated power level and the desired transmitter power level.
A transmission arrangement is provided for transmitting data continuously in the time domain. The arrangement includes at least one programmable amplifier in the baseband or in the radio frequency path in the signal processing chain for the signal which is to be transmitted. This programmable amplifier is distinguished in that the signal which actuates the programmable amplifier is a discrete-value signal. By dispensing with complex digital/analog converters, the principle described allows markedly reduced power consumption in transmitters which use code multiple access methods.
