Direct conversion frequency/phase shift keying demodulator.

摘要

The invention relates to a demodulator (2) and to a radio receiver having such a demodulator and, more particularly, to a demodulator for demodulating signals which were digitized by a direct detecting method in which a circuit scale is small and an electric power consumption is small and to a radio receiver having such a demodulator (2). Particularly, it is a characteristic portion that a limiter (1) in the demodulator comprises: a circuit for obtaining absolute values of the digital signals (I signal, Q signal) which are produced from an angle modulated wave and whose phases are mutually orthogonal; a circuit for outputting the sum (¦I¦ + ¦Q¦) of the absolute values or the larger one M (¦I¦ , ¦Q¦) of the absolute values; a controller for producing a control signal according to an output of the above circuit; and scalers which change the amplitudes of the first and second digital signals in accordance with the control signal and which are constructed by a plurality of shift registers and adders.