摘要:
Mobile communication equipment comprises a power amplifier for amplifying a transmission signal and a feedback circuit for providing feedback to allow the above-described power amplifier to output a transmission-power set value. The feedback circuit comprises an error detection unit for detecting an error between a power value obtained by detecting a portion of the power of the transmission signal amplified by the power amplifier and the transmission-power set value specified by the above-described transmission-power specifying unit, a Loop-gain generating unit for periodically switching two different loop-gain values at a predetermined time ratio to output one of them, a loop-gain multiplying unit for multiplying the error detected by the error-detection unit by the loop-gain value outputted from the loop-gain generating unit to output an error value that results from the multiplication, and a feedback-amount generating unit for integrating the error value outputted from the loop-gain multiplying unit to generate a specific amount of the feedback.
摘要:
Compensation for variations in temperature and manufacturing process of a MOSFET operating in its sub-threshold mode. The compensation may include circuitry containing at least a second MOSFET that may also operate in its sub-threshold mode. The operational characteristics of the second MOSFET may be closely matched to those of the first MOSFET, and the second MOSFET may be contained on the same substrate.
摘要:
Cellule d'atténuation comportant une première paire et une seconde paire différentielle de transistors bipolaires. Un dispositif de commande du gain applique un potentiel VA - VB entre les bases des deux paires différentielles et comporte un jeu de trois diodes dans lesquelles on fait respectivement parcourir un courant IA, IB et la somme IA + IB des deux courants précédents. Les deux diodes parcourues par un courant IB et IA+IB génèrent un potentiel, respectivement VB et VC et la différence entre ces deux potentiels sert à générer une grandeur Iz utilisée dans une boucle d'asservissement. Une consigne Vct est transformée en une information Ix, puis en une information Iy proportionnelle à la température absolue T, et un amplificateur d'erreur utilise l'information Iy - Iz et génère les courants IA et IB en minimisant cette différence.
摘要:
In an automatic gain control amplifier ( AGCa ), an RF automatic gain controller (2) controls the gain of a radio frequency signal ( Srf ). A frequency converter (3, 4) frequency-converts the radio frequency signal ( Srfa ) into an intermediate frequency signal ( Sifa ). An IF automatic gain controller (5) controls the gain of the intermediate frequency ( Sifa ). A level detector ( LDa ) detects a signal level of the gain-controlled intermediate frequency signal ( Sifa ), and generates a level signal ( SLa ). An automatic gain control signal generator (SGa, SGb) separately controls, based the level signal ( SLa, SLb ), the RF automatic gain controller (2) and the IF automatic gain controller (5).
摘要:
A power amplifier has a feedback loop to control the signal level thereof. A current sensing amplifier in the feedback loop is controlled to remove any offset. The input signal is compared with a reference level. When the input signal is below the reference level, an offset compensation value for the current sensing amplifier is stored. When the input signal is above the reference level, the previously stored offset compensation value continues to be applied. The circuit is of particular application in a TDMA radio transmitter.
摘要:
A gain control circuit 9 comprises gain controllers 2, 3 and a gain control signal generator 1a. Temperature characteristics of the gain of the controllers 2, 3 vary depending on the amount of a circuit gain control signal. The gain control signal generator 1a outputs gain control signals for controlling the gain of gain controllers 2, 3. Since gain controllers 2, 3 are connected in serial form and a predetermined offset to gain control signals 5, 6 is given, it has become possible to simply configure a gain control circuit having a wide dynamic range and good temperature characteristics.