Field Effect Transistor Circuit for Modulator and Demodulator Applications.
DEPARTMENT OF THE NAVY WASHINGTON DC
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A double balanced modulator-demodulator consisting of two pairs of field effect transistors. A field effect transistor is connected in series between the source electrodes of each of the field effect transistor pairs. The field effect transistors making up each pair are biased so that they operate in the saturated mode. Each of the transistors connected between the source electrodes of the transistor pairs are biased to operate in the linear mode such that drain current varies linearly with drain voltage. A first input signal is connected across the gate electrodes of the transistor pairs while a second input signal is connected across the gate electrodes of the connecting transistors. Bias for each of the transistor pair is provided by means of a field effect transistor connected between the source electrodes of the transistors pairs and ground. The gates and source electrodes of transistors forming the bias circuit are connected to ground. The outputs of the two pairs are connected in parallel such that the differential output current is proportional to the product of the input signals. Author
- Electrical and Electronic Equipment