U6101B

The U6101B has the following features including Frequency range from 390 to 520 MHz;Two unbalanced switchable inputs;High input sensitivity;AGC control range -35 dB;Internal AGC detector;Additionally external gain control and output level setting possible.

The  U6101B  is  a  monolithic  integrated  circuit  in TEMIC's UHF 5 technology for Satellite Digital Video Broadcasting(DVBS) and other digital direct satellite service applications. The circuit U6101B operates in a wide frequency range and in a large input level range.Implemented are two orthogonal mixer stages (precise phase-matched by a control loop), a gain-controlled IF amplifier of high input sensitivity with two switchable isolated inputs, and an AGC-system for tuner and IF level control.Alternatively the output level of U6101B may be controlled automatically, e.g., via the channel decoder AGC signal output.The local oscillator operates at IF input frequency. The oscillator signal is internally doubled and divided again to generate the orthogonal mixer driving signals.The input signal is via two single ended constant gain amplifiers with selectable inputs connected to a gain controlled  amplifier.The  differential output signal remains of constant amplitude to provide-behind splitting up-optimised dynamic operation points for a pair of identical mixers. The mixer stages of U6101B are driven by two orthogonal oscillator signals, to generate the I- and Q-components.

To avoid fast system lock in time and driving the A/D converters U6101B with defined output levels, in one channel the output signal will be peak-level detected and in an internally loop level controlled. So the output signal amplitudes   are   independent  of   frequency   and characteristic of the QPSK modulation. The output level U6101B can be set via an external potentiometer (or at two fixed levels  by  pin  programming)  according  the  actual application. External loop control by a channel decoder generated AGC signal is provided.The DC-component of the AGC loop affects the IF input level. This signal is internally compared with a adjustable threshold and generates a tuner AGC signal.