摘要:
In a receiver circuit for demodulating a high-frequency signal, a limiting amplifier stage with a downstream sigma-delta converter is connected in series with a mixer stage that transforms a high-frequency signal that is supplied at its input into an intermediate-frequency signal. The intermediate-frequency signal at the output of the limiting amplifier stage is value-discrete and time-continuous. The described receiver architecture has a high sensitivity, is substantially independent of production tolerances, and occupies a small area; therefore, it is particularly suitable for mobile radio applications.
摘要:
A demodulator has a resistor and a capacitor that may be subject to tolerances. For tolerance correction, the FM demodulator is preferably supplied with a reference frequency, which corresponds to the nominal mid-frequency of the demodulator, which is a function of the resistor and the capacitor. Any discrepancy between the actual mid-frequency of the demodulator and its nominal mid-frequency leads to the production of a voltage that differs from a nominal voltage at the output. A detector detects this error and adjusts the values of the resistor or capacitor until the error between the nominal voltage and the voltage is zero or is a minimum. The described principle can be used, for example, in integrated mobile radio receivers.
摘要:
A radio receiver with a low intermediate frequency has a first mixer stage that can be fed with a modulated input signal and at whose output a complex intermediate frequency signal can be derived. Connected downstream of the first mixer stage is a limiting amplifier at whose output the intermediate frequency signal is present in a discrete-value and continuous-time fashion. A sampling device, for sampling the intermediate frequency signal, and a digital demodulator unit are connected to the output of this limiter. The demodulated input signal can be derived at the output of this digital demodulator unit. The present radio receiver requires a low chip area in conjunction with low power consumption, but offers a high sensitivity and accuracy based on the digitally implemented demodulation.
摘要:
A digital telecommunication facility has a base station and one or more cordless mobile units. The telecommunication facility exchanges data between the mobile units and the base station in units of two or more TDMA frames.
摘要:
A circuit configuration of a frequency divider includes a prescaler with at least two different division ratios and at least two further different division ratios. A main counter connected to an output of the prescaler has an adjustable division ratio. A first lower-level swallow counter has an adjustable division ratio and can change the division ratio of the prescaler. At least one second lower-level swallow counter has an adjustable division ratio, is provided at the output of the main counter and can change the division ratio of the prescaler between the two further division ratios.
摘要:
For the purpose of error masking, binary representation of parameter values are precoded at the transmitting end by a linear block code before transmission over a faulty channel, and the redundant information added in this way is not used at the receiving end for error detection within the binary parameter representations, but is utilized in the course of a parameter estimation to improve the quality of the estimated parameter values.
摘要:
An amplifier array having digitally adjustable total gain and being constructed of a multiplicity of switchable individual amplifiers, includes at least two parallel, selectively triggerable gain paths having input and output sides. Each of the gain paths has an input amplifier and a switching amplifier being connected downstream of the input amplifier and being switchable in stages. A multiplexer has inputs connected to the output side of the gain paths and has an output. An amplifier array input is connected to the input side of the gain paths and an amplifier array output is formed by the output of the multiplexer. In a mobile radio receiver having the amplifier array, a total gain of the amplifier array is adjusted for setting an output signal of the mobile radio receiver at a constant level.
摘要:
A circuit configuration being made by differential technology for dividing a clock signal with switchable divider ratios of 4/5 by emitter coupled logic, includes first, second and third series-connected flip-flops each having an output, a data input and a clock input. The output of the second flip-flop is coupled to the data input of the third flip-flop, and the clock inputs of the first, second and third flip-flops are acted upon by a clock signal. A first AND gate is connected upstream of the first flip-flop and has a first input being acted upon by a control signal for switching over the divider ratio, and a second input being acted upon by an inverted signal from the output of the third flip-flop. A second AND gate is connected between the first and second flip-flops and has an output connected to the data input of the second flip-flop, a first input receiving an inverted signal from the output of the first flip-flop, and a second input being acted upon by the inverted signal from the output of the third flip-flop.
摘要:
A circuit is provided for time division duplexing with a frequency hopping technique and has a total of just two frequency synthesizers for the transmission and reception paths and only one up-converter in the transmission path. The UHF synthesizer frequency is additionally subjected to frequency division prior to insertion as a heterodyne frequency of the assigned converter in the transmission and reception paths, which, owing to the shorter transient recovery times, makes it possible to utilize the UHF frequency synthesizers at different frequencies for the transmission and reception slots, respectively. A particular application is in cordless telephones.
摘要:
The ON and OFF states of a second device are controlled by a first device through a three-conductor bus. The bus carries data, clock, and enable signals and the second device is in the OFF state when all the signals of the three-conductor bus have an L level. The second device is in the ON state when at least one of the signals has an H level (higher potential than the L level). The enable signal is set to the H level during the data transmission. Otherwise, it carries an L level, while the data or clock signal has an H level. The system obviates an additional housing pin. The operating state information is transmitted relatively rapidly.