Double balanced mixer

1. What is a double balanced mixer?
2. What are the differences between single and double balanced mixers?
3. Why double balanced mixer is used in a communication circuit?
4. What is triple balanced mixer?

What is a double balanced mixer?

The double balanced mixer is a diode bridge mixer that uses two single-ended to differential transformers, or baluns, to create the multiplication of two input frequencies and cancel many of the unwanted harmonics and signals.

What are the differences between single and double balanced mixers?

A single-balanced mixer has a pair of diodes, where one port (typically LO) has a balun that drives the diodes in a balanced configuration. A double-balanced mixer has balanced inputs on RF and LO ports and uses four diodes connected in a ring. Balancing the ports reduces unwanted mixer spurs and improves isolation.

Why double balanced mixer is used in a communication circuit?

A double balanced mixer has both its inputs applied to differential circuits, so that neither of the input signals and only the product signal appears at the output. Double balanced mixers are more complex and require higher drive levels than unbalanced and single balanced designs.

What is triple balanced mixer?

Triple Balanced Mixers (also called Double Doubly-Balanced Mixers) have three separate baluns for LO, RF and IF ports. This structure helps provide wide bandwidth and good L-R, L-I and R-I isolations, return loss, compression and IP3, all at the expense of 3dB higher LO power.