Modulator comprising a dual-frequency oscillator and a synthesizer

Abstract

Oscillators (10) which oscillate at a fundamental frequency also generate harmonics. The fundamental frequency or a lower harmonic is used for feedback purposes, and a harmonic higher than either the fundamental frequency or the lower harmonic is used for output purposes. As a result, the oscillators (10) operate at a lower frequency than an output frequency and are low cost. Synthesizers (20) coupled to the oscillators (10) also operate at this lower frequency, and modulators (5) comprising such oscillators (10) and synthesizers (20) are low cost. A lower power consumption and less sensitivity to disturbing fields are further advantages. Filtering has become less complicated, and a smaller number of components has resulted in smaller dimensions. The oscillators (10) comprise tuning circuits (11) and amplifiers (12), which amplifiers (12) are fed back via feedback circuits (13). Such an amplifier (12) may comprise just a single transistor (40).

Description

technical field [0001] The invention relates to a device comprising a modulator comprising an oscillator and a synthesizer, and also to a modulator comprising an oscillator and a synthesizer, and an oscillator. [0002] Examples of such devices are eg wireless (digital) speaker systems, wireless (digital) headphones, small phones and other consumer products. Background technique [0003] A known modulator is known from US 5,281,930, in its figure 1 a voltage controlled oscillator is disclosed, which receives the modulating signal via a weighting filter and the tuning signal from a phase comparator via a low pass filter. A phase comparator compares the divided output signal of the voltage controlled oscillator with a reference signal generator. To divide the output signal of the voltage controlled oscillator, a frequency divider is used. This combination of phase detector and frequency divider can be replaced by a synthesizer. [0004] Known modulators comprising oscillato...

AI Technical Summary

Problems solved by technology

[0004] Known modulators comprising oscillators and synthesizers have disadvantages, not least because of the fact that the modulators are relatively expensive: either one of the oscillators and synthesizers needs to operate at high modulation frequencies, which makes oscillators and synthesizers are expensive, or oscillators and synthesizers operate e.g. at half the modulation frequency, in which case an additional frequency multiplier is required

In both cases, the modulator itself, as well as the equipment that includes it, becomes relatively expensive

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