A low frequency signal generating portion 1 generates a first discrete signal (a signal sampled at a first sampling rate f.sub.1). A band pass portion 2 operates at a second sampling rate f.sub.2, performs a frequency selecting operation to a second discrete signal generated when the first discrete signal generated by the low frequency signal generating portion 1 is inputted, and generates a modulated signal with a prescribed center frequency.

The invention relates to a modulator comprising a first differential amplifier (6) which receives an input signal and a correction signal for adjusting the quiescent currents on the first and second output. The first differential amplifier (6) is coupled to a second differential amplifier (19) and a third differential amplifier (22), which receive the carrier signal and which supply the modulated signal. A difference signal proportional to the difference between the current of the first output a...

An operational transconductance amplifier receives an input signal to be modulated at one of its inverting or non-inverting input terminals and a modulating signal at its transconductance control terminal. A signal proportioning circuit, also receptive of the modulating signal minimizes feedthrough of the modulating signal to the output terminal by applying a portion thereof to both the inverting and non-inverting input terminals.

In an amplitude modulator, a delta sigma modulator converts a digital or analog modulation signal into a binary signal. The binary signal and a carrier signal are sent to a multiplication circuit. The phase of the carrier signal is changed to normal phase or opposite phase. The resultant carrier signal is output as an amplitude modulation wave. An orthogonal modulator sends a local oscillation signal to a phase shifter. The phase shifter outputs two carrier signals with phases which differ by 90...

In a modulator for converting two digital signals of I channel and Q channel in base band into analog signals and for converting a component of the signals whose phase is the same as a carrier and another component of the signals whose phase is orthogonal to the carrier so as to produce an orthogonally modulated wave, the two digital signals are connected to one signal train by time-sharing and multiplexing them and the converted analog signals are separated to two analog signals for the I chann...

A modulator according to the invention includes: a PLL circuit that detects a phase difference between an input signal and a reference signal, an AGC circuit that controls a gain of a modulating signal and outputs a control signal, and a voltage controlled oscillation circuit that controls an oscillation frequency of a signal outputted from the PLL circuit on the basis of the control signal. Here, the voltage controlled oscillation circuit includes: a first voltage controlled reactance unit that...

In a modulator, a linear converter inputs modulation signals and feed-back signals as an input vector and linearly converts the input vector. An encoder vector-quantizes the linearly converted vector and outputs the resultant signals as selection signals. A vector decoder decodes the encoded output into the plurality of feed-back signals. A selector selects and outputs one of signals with the same frequency and different phase or amplitude according to the selection signals.

In an amplitude modulator, a delta sigma modulator converts a digital or analog modulation signal into a binary signal. The binary signal and a carrier signal are sent to a multiplication circuit. The phase of the carrier signal is changed to normal phase or opposite phase. The resultant carrier signal is output as an amplitude modulation wave. An orthogonal modulator sends a local oscillation signal to a phase shifter. The phase shifter outputs two carrier signals with phases which differ by 90...

In a modulator, an attenuator attenuates an input signal, a delay element gives a delay of 1 sample period to the attenuated signal, an adder subtracts a quantized signal that has been fed back with a delay of 1 sample period, from the delayed signal, two or more integrators integrate a result of the subtraction, an adder which adds outputs of the respective integrators and the attenuated signal, and a quantizer quantizes a result of the addition, outputs a result of the quantization as an outpu...

A modulator according to the invention includes: a PLL circuit that detects a phase difference between an input signal and a reference signal, an AGC circuit that controls a gain of a modulating signal and outputs a control signal, and a voltage controlled oscillation circuit that controls an oscillation frequency of a signal outputted from the PLL circuit on the basis of the control signal. Here, the voltage controlled oscillation circuit includes: a first voltage controlled reactance unit that...