As a mixer, its balanced operation cancels out many unwanted mixing products, resulting in a "cleaner" output.
It is a generalized case of an early circuit first used by Howard Jones in 1963,[2] invented independently and greatly augmented by Barrie Gilbert in 1967.
[4] However, the utility of this generalization in practical microelectronics settings is limited due to the large voltage headroom needed to keep all of the transistors in the proper (forward-active) region of operation.
However, in the cells later invented by Gilbert, shown in the figure on the right, there are two additional diode-connected transistors (labeled as V1 and V2).
This additional diode cell topology is typically used when a low distortion voltage-controlled amplifier (VCA) is required.