Broadband multiplication circuit for use in the video band

Although each input terminal is a differential input, it has a larger bias current (800nA) than a general OP amplifier
. Therefore, if a capacitive coupling is used for input, attention must be paid to the confidence
resistor value (should also be added to the input terminal of X2, Balance resistor, etc.)
    , use it as a balance modulation circuit, input the carrier from Y, and
when the modulation signal is equal to zero, adjust the variable resistor v to achieve carrier balance (
minimum carrier leakage).
    The power supply of VRi adopts circuit power supply. If the stability of the power supply is not good,
the load balance will be destroyed. Since the bandwidth is ioMHz/-3d B. Care should be taken when using it in a circuit with phase shift
.