Abstract: At the onset of an operation, a level of a base band signal at an input side of a variable gain amplifying circuit is detected by a logarithmic amplifier having a wide dynamic range, and, a control unit controls a gain of a low-noise amplifier in a previous step of a low-pass filter based on the detected level and also controls a gain of variable gain amplifier, whereby saturation at an analog base band portion is prevented even when the level of the input signal is high.

Abstract: A low cost redundancy scheme for the radio frequency front end of a wireless hub that requires a minimum number of down converters and upstream receivers to implement. The redundancy scheme may also be used as a back-up support for any upstream channel that is provided with a greater amount of data than the other upstream channels.

Abstract: A multimode fast attack automatic gain control (AGC) circuit (100) includes an analog feedback loop and a digital feedback loop. The analog feedback loop is switched into the amplifier stage (102) by a first switch (126) when dynamic control of the gain attenuation is desired. The digital feedback loop is switched into the amplifier stage when attenuation is to be adjusted periodically, such as between sequentially received time slots in a time division multiple access (TDMA) mode of communication.

Abstract: A controlled receive device is disclosed having an amplifier circuit, which receives an input signal, and a control circuit which receives the input signal and outputs a controlled signal to a receiver. The receiver outputs an output signal. A controller varies the gain of the amplifier circuit in response to levels of the controlled signal and the output signal. The control circuit outputs a controlled indicator signal indicative of a level of the controlled signal and the receiver outputs an output indicator signal indicative of the output signal level. The controlled indicator signal and the output indicator signal are compared using comparators, to respective reference or threshold levels for producing control signals used by the controller for varying the amplifier gain.

Abstract: A DC offset correction method and apparatus. Several DC offset correction schemes including a digital binary search scheme (100), a digital slow averaging scheme (200) and an analog integration (50) scheme are provided. A controller (160) selects one or more of the correction schemes in accordance with the desired characteristics provided by each scheme.

Abstract: A mobile communication device comprising a handset achieves gain control of a received signal by adjusting gain of the received signal based on A/D converter samples of the received signal, rather than on power I2 and Q2 calculations of the received signal. The device processes a received signal and adjusts its gain by first setting signal gain to a maximum level, then providing the amplified received signal to an analog-to-digital converter (ADC) that produces a predetermined number of ADC signal sample values in a single cycle of an estimated signal frequency of the received signal. Setting the signal gain to a maximum initial level will cause a number of ADC signal sample values to have full scale magnitude, indicating saturation of the ADC.

Abstract: A gain control circuit comprises a variable gain circuit having a predetermined gain control range and a control voltage supply circuit for supplying an internal control voltage to the variable gain circuit as a gain control signal. In this gain control circuit, the control voltage supply circuit generates the internal control voltage in response to an external control voltage as to compensate a linearity of the variable gain circuit to an extent of the external control voltage where the variable gain circuit loses a linearity. This gain control circuit is applied to an AGC circuit of a transmitting stage in a CDMA type mobile phone.

Abstract: A digital automatic gain control device for use in a communication terminal of a mobile radio communication system employing a time-division duplex (TDD) transmission. A transmission power amplifier and a reception amplifier, which constitute the communication terminal, are fully composed of digital elements. In a transmission mode, a reception data latch is cleared to turn off the reception amplifier, so as to prevent a distortion of a modulated transmission signal due to regeneration and coupling of a modulated transmission waveform generated from a receiver. On the contrary, in a reception mode, a transmission data latch is cleared to prevent the carrier generated from the transmitter from being leaked toward a receiver, thereby preventing deterioration of a reception sensitivity of the receiver. Therefore, the transmission and reception gain can be accurately controlled based on the accurate timing control by the control processor.

Abstract: In a method and circuit for the amplification of input signals of a hearing aid, a compression of the signals picked up by the hearing aid ensues in a AGC circuit dependent on the acquirable signal level. For assuring a dynamics compression, the method and circuit implement a signal analysis for the recognition of the acoustic situation in addition to the acquisition of the signal level of the input signal, and the behavior of the dynamics compression is adaptively varied on the basis of the result of the signal analysis. A fixed input-output characteristic that is usually defined on the basis of stationary signals forms the basis of parameter settings of a dynamics compression has been used in conventional calculations. The resulting time behavior for the compensation of input signals by a hearing aid exhibits an effectively different compression given time-variable, modulated signals, particularly given speech. The result is that the compression parameters are not optimally set for all signals.

Abstract: Carrier signals received by a receiver architecture for an amplitude spectrum of the carrier signal prescribed by the employment of the receiver architecture even given small modulation indices, a low-noise amplifier (VS) preceding a synthesizer (SYN) of the receiver is either turned off dependent on the field strength received with the carrier signal or is fashioned such that the maximum output power of the amplifier (VS) at the possible amplitude spectrum of the carrier signal never lies above the compression point of the mixer/mixers in the synthesizer (SYN).

Abstract: An optical signal receiving apparatus capable of substantially instantaneously and stably discriminating the logic from the header of a burst-like optical signal comprising a pre-amplifier circuit for amplifying an output from a photodiode receiving cell signals, a dummy side variable gain amplifying unit for performing the gain control by feedback control with respect to the output from the pre-amplifier circuit and outputting the gain at that time as gain information, a memory unit for holding the gain information, and a signal side variable gain amplifying unit for performing the gain control by feedfoward control by using the gain set by the gain information and outputting the amplified signal.