The guard amplifier is a unity-gain amplifier with very high input impedance. 保护放大器是一个具有非常高输入阻抗的单位增益放大器。
To gain further bisymmetric baseband signals, the proposed transconductance stage is formed with a cross-coupled type. 之后经过可变增益放大器将升频后之讯号放大到功率放大器所要求之强度。