Amplitude Modulator with OTA

Circuit described in the schematic diagram below can achieve 99% modulation easily with maximum frequency of 200kHz. The amplification of this circuit can be controlled easily since the transconductance of an operational transconductance amplifier is directly propotional to the control current Iabc. The product from input voltage times the transconductance is the output current of this circuit. Here is the […]

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50 kHz FM Optical Receiver

Frequency modulation (FM) can be used to transmit analog voltage level signal with good noise immunity. The transmission itself¬† might employs different methods, and this circuit uses free air optical medium. This optical receiver circuit is built using a L14G2 detector, two stages of gain, and a FM demodulator. To obtain better sensitivity, we can use more stages of stabilized […]

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LM331 Frequency to Voltage Converter

The frequency to voltage converter circuit illustrated in the schematic diagram below produces a 10 V output for 10 kHz full scale input (square waves or pulses).¬† The simplicity of the circuit doesn’t mean a bad performance: this circuit has linearity about 0.06% at full scale. For your note, there is a trade-off between ripple versus response time. With Cfilter […]

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