A full wave rectifier includes an operational amplifier having an inverting terminal connected to the emitter of a transistor. A first resistor is connected between a first power source and the collector of the transistor. A second resistor is connected between a second power source and the emitter of the transistor. When the first and second resistors have an identical value and first and second power sources have same absolute voltage but opposite polarity, the voltage on the transistor collector represents the rectification of the voltage applied to the non-inverting input of the operational amplifier.
A full-wave rectifier having a limited number of circuit elements comprises an amplifier, such as an operational amplifier, having an inverting input held at a reference potential, a non-inverting input receiving an input signal through a first resistor and an output, a transistor having its base connected to the output of the amplifier and its collector connected to the non-inverting input of the amplifier through a second resistor and optionally an output circuit for producing an output signal from the connection point between the collector of the transistor and the second resistor.
An AC-DC transformation circuit according to this invention facilitates operational stability by transforming an AC inputted voltage first into current and then transforming the current into a DC voltage.
An improved transresistance amplifier for generating an output voltage from an input current includes: a current buffer for shifting a dominant pole associated with the input current to a higher frequency, thereby increasing the bandwidth of the transresistance amplifier; a current amplifier for amplifying the buffered input current, thereby generating a high transresistance for the transresistance amplifier; and an I/V amplifier for converting the buffered and amplified input current into the output voltage. The current amplifier includes a current mirror and a current source that draws current from the mirrored side of the current mirror. Also, the current buffer includes a buffering transistor that draws current from the input side of the current mirror, and a differential amplifier having an output that controls the flow of current through the buffering transistor, part of which is drawn by another current source connected to the buffering transistor, and part of which is drawn to make up the input current. The improved transresistance amplifier is particularly useful as part of a pick-up circuit in CD and DVD-ROM applications.
A full wave rectifier/averaging circuit for processing an input signal having a large dynamic range. A rectification circuit is responsive to the input signal for providing a first signal to a current mirror whereby the current mirror provides a second signal in response to the first signal. An averaging circuit is coupled to the current mirror to perform averaging of the second signal. An output circuit is coupled to the averaging circuit to provide an output signal at an output terminal.
The present invention concerns a circuit processes the power signal emitted from an RF power sensor (SK) of a radio telephone to create a detector voltage which is proportional to the power level of the radio telephone transmitter. The circuit comprises a transistor (Q2) acting as an active rectifier, which in the ascending part of the positive half cycle of the power signal charges a capacitor (C3). During the descending part of the power signal the capacitor starts to discharge with a time constant which is remarkably greater than the cycle length of the power signal. The transistor is biassed by means of a transistor (Q1) so that it is conductive even at the lowest power levels.
