Modulators – Amplitude modulator – Nonlinear device controlled by modulating signal
Patent
1986-12-19
1988-08-23
Grimm, Siegfried H.
Modulators
Amplitude modulator
Nonlinear device controlled by modulating signal
324309, 332 9T, 332 31T, 332 37D, 332 44, G01R 3322, H03K 700
Patent
active
047664002
ABSTRACT:
A variable-transconductance four-quadrant Gilbert-type modulator comprises a differential-transconductance amplifier, a fixed current source, a current sensing resistor, variable-transconductance circuitry, and feedback circuitry. The feedback circuitry is operatively connected to the differential-transconductance amplifier and to the current sensing resistor to receive the modulation voltage signal and to cause the voltage across the current sensing resistor to follow the voltage of the modulation voltage signal thereby causing the differential output current of the differential-transconductance amplifier to be directly proportional to the voltage on its input port thereby improving the linearity of the modulator. Also provided is an isolation output amplifier on the modulated output of the modulator to improve isolation between the carrier input signal and the modulated output.
REFERENCES:
patent: 4403194 (1983-09-01), Talbot
patent: 4654607 (1987-03-01), Ishikawa
B. Gilbert, "A Precise Four-Quadrant Multiplier with Subnanosecond Response", IEEE Journal of Solid-State Circuits, SC-3, No. 4, pp. 365-367 (Dec. 1968).
Clarke et al., Communication Circuits: Analysis and Design (Addison-Wesley Publishing Company 1971).
Grimm Siegfried H.
Kabushiki Kaisha Toshiba
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