Junction field effect transistor mixer circuit

The junction field effect transistor mixer circuit is shown in the figure.
  The signal voltage and the local oscillator signal voltage are input from the gate at the same time. Since the drain current and gate voltage of the junction field effect transistor satisfy the square ratio
relationship, frequency mixing can be achieved.
  Gate field effect transistors have small gate-source capacitance and large forward transmission admittance, making them suitable for use as ultra-high frequency mixers.