What is a Gilbert cell multiplier?
1 Answer
A Gilbert cell multiplier, also known as a Gilbert cell mixer or simply a Gilbert cell, is a fundamental building block used in analog circuits, particularly in radio frequency (RF) and microwave applications. It is a key component in many communication systems, such as modulators, demodulators, frequency synthesizers, and phase-locked loops.
The Gilbert cell was invented by Barrie Gilbert in 1968 and has since become a widely used circuit due to its excellent performance characteristics. It is a type of differential amplifier with active devices (transistors) that allows it to perform a multiplication operation on two input signals.
The basic Gilbert cell consists of four transistors arranged in a balanced configuration, often implemented as two differential pairs. The two inputs are fed to the bases of the first pair, and the outputs of this pair are connected to the bases of the second pair. The emitters of the first pair are typically connected to a constant current source, while the collectors of the second pair are tied together to provide the output.
When two signals are applied to the input of the Gilbert cell, they are multiplied together, and the resulting product is obtained at the output. Mathematically, if the input signals are A and B, the output signal is proportional to A * B.
Gilbert cell multipliers are known for their high linearity, good isolation between the input ports, and low noise figure. These characteristics make them suitable for applications that require frequency translation, phase modulation, amplitude modulation, mixing of signals, and other operations commonly found in RF and wireless communication systems.
In summary, a Gilbert cell multiplier is a specialized circuit that performs the multiplication of two input signals with high accuracy and is widely used in various RF and communication applications.
The Gilbert cell was invented by Barrie Gilbert in 1968 and has since become a widely used circuit due to its excellent performance characteristics. It is a type of differential amplifier with active devices (transistors) that allows it to perform a multiplication operation on two input signals.
The basic Gilbert cell consists of four transistors arranged in a balanced configuration, often implemented as two differential pairs. The two inputs are fed to the bases of the first pair, and the outputs of this pair are connected to the bases of the second pair. The emitters of the first pair are typically connected to a constant current source, while the collectors of the second pair are tied together to provide the output.
When two signals are applied to the input of the Gilbert cell, they are multiplied together, and the resulting product is obtained at the output. Mathematically, if the input signals are A and B, the output signal is proportional to A * B.
Gilbert cell multipliers are known for their high linearity, good isolation between the input ports, and low noise figure. These characteristics make them suitable for applications that require frequency translation, phase modulation, amplitude modulation, mixing of signals, and other operations commonly found in RF and wireless communication systems.
In summary, a Gilbert cell multiplier is a specialized circuit that performs the multiplication of two input signals with high accuracy and is widely used in various RF and communication applications.