Low power for a radio transmitter is indicated by an output power detector voltage falling below a low power reference voltage derived from an existing power control circuit.

It is an object of the present invention to provide a transmitter which is inexpensive and small in size and is reduced in power dissipation and besides wherein the output power of a power amplifier can be varied to an arbitrary value. A phase modulator, a variable attenuator, a high power amplifier, a directional coupler, a detector, an error amplifier, a switch and an analog multiplier form an envelope feedback loop. The envelope feedback loop controls an envelope of a modulated wave detected ...

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 detecte...

A method and a device for controlling a radio transmitter. In the method, the radio transmitter is alternately caused to assume an ON state in which a desired outbound RF power is transmitted, and an OFF state in which no RF power is transmitted, the RF power being determined in the ON state by using a power control signal (V.sub.c) controlling the amplification of transmitter amplifiers (3, 4). For ensuring that the data period falls within the useful period of the transmitter, within which the...

An automatic power control (APC) circuit for use with a radio telecommunication apparatus. The apparatus transmits radio frequency signals at a power level prescribed by a level control signal. In the automatic power control circuit, transmission power level is detected from the output of a duplexer. Accordingly, even if signal loss in a filter of the duplexer varies on the frequency of signals passing therethrough, transmission power level is accurately detected and the detected level is feedba...

An apparatus for controlling the output power of a transmitter installed in a vehicle or used in a mobile radio communication equipment and more particularly to apparatus and method for accurately measuring and controlling over a wide range the output power of a radio frequency to be transmitted. The apparatus has a voltage level adjusting unit for amplifying a voltage of a radio frequency signal to be transmitted in correspondence with a difference between output power set data and measuring ou...

A transmission system for digital mobile radio installation mobile terminals includes an attenuator on the input side of the mixer in order to apply to the latter signals at an rms level of only approximately 70 millivolts. The preamplifier is therefore a very high gain amplifier (typically 30 dB) and is followed by a level limiter circuit.

A remote power measuring device (1) is used to measure the power output of the transmission system (20). The measured power is then transmitted to a controller (5) and used by the controller (5), along with preset calibration data (41) for each power amplifier (3), to determine power output adjustment factors (22). The adjustment factors (22) are then communicated to the appropriate power amplifier (3) to adjust its output.

A temperature compensated detector includes a series circuit formed by successively connecting a first resistor, a first diode, a second diode having a characteristic substantially equal to that of the first diode, and a second resistor, a third resistor, and a fourth resistor. A terminal supplied with a predetermined bias voltage is grounded through the series circuit. A high-frequency signal to be detected is supplied to a junction point between the first resistor and the first diode or a junc...

A transmitter architecture is disclosed which offers a new combination of signal shaping and power control which optimizes transmitter noise figure performance. The disclosed apparatus and method is implemented by separating the shaping element (303) from the power control elements (406, 412, 418) in frequency. Placing the shaping element (303) at a fixed intermediate frequency (IF) allows for the use of readily available, temperature stable shaping elements while distributing the power control ...