Contents
What do you need to know about a balun?
A balun is any three port device with a matched input and differential outputs. It is most succinctly described by the required (ideal) S-parameters: Note what is implied by this: • A balun is a three port power splitter, similar to a Wilkinson or resistive power divider. • The two outputs will be equal and opposite.
Which is the correct part number for a balun?
A 1:1 balun has the widest operating frequency range, lowest core stress, and provides the best overall balance of any balun for given cost, size, and weight. The DX Engineering part number of the correct unit would be the DXE-BAL050H10AT Current Balun or the DXE-BAL050H11CT Current Balun depending on power levels.
How does the balun affect the common mode current?
In the case of a 1:1 ratio current balun, core flux density or “magnetizing stress” on the balun core is independent of load impedance or load mismatch. Only common-mode current affects the core.
Which is the correct balun for a Windom dipole?
The best balun for the Windom or Off-Center Fed Dipole is a 4:1 ratio current balun. The DX Engineering part number of the correct balun would be the DXE-BAL200-H10-A or the DXE-BAL200H11-C .
What makes a balun equal to a quadrature coupler?
A balun has equal power outputs just like a Wilkinson power divider, resistive power divider, or quadrature hybrid coupler. However, it has a 180° phase difference between outputs, while the power dividers have 0° phase difference and quad hybrids have 90° phase difference.
What are the different types of Marki baluns?
In general Marki baluns can be divided into two types. Those with magnetic coupling perform below 10 MHz, while those with only capacitive coupling have low end performance limited to about 1 GHz, but can operate up to millimeter wave frequencies.
How does a balun work in the time domain?
– In time domain this means the voltage of one balanced output is the negative of the other balanced output. • The unbalanced input is matched to the input transmission line impedance (usually 50 Ω). • Unlike an isolator or circulator, a balun is a reciprocal device that can be used bidirectionally.
What kind of circuit is a tapered balun?
The tapered balun, in turn, is very similar to other type of coupled line baluns such as the Marchand balun (Fig. 7), coplanar waveguide balun, coaxial balun, planar transformer (spiral) balun, and many other types of coupled line circuits that can be used as baluns, and will not be reviewed here.
Which is better a balun or an amplifier?
Many designers prefer baluns because they think they provide superior distortion over amplifiers. That may be true at very high frequencies (>>1GHz), but amplifier manufacturers like TI provide FDAs that are better specified for amplitude balance and distortion than baluns at many common-use frequencies, especially in the DC-1GHz range.
When to use a balun in a driver circuit?
Baluns are often used to convert a single-ended signal to differential, without adding noise and while maintaining good distortion. A common example of that is in the driver circuit for a high-speed, differential-input analog-to-digital converter (ADC).
How does load impedance affect a voltage balun?
Unlike a 1:1 ratio current balun, a voltage balun will always magnetize its core in direct proportion to load voltages. In a voltage balun, load impedance directly affects core heating and flux density.
What’s the average amplitude balance of a balun?
Although it is called amplitude balance, it is usually specified in dB and actually gives the match between output power magnitude. Low performance baluns have amplitude balance of ±1.5 dB max and ±1 dB typical, while Marki products approach ±.5 dB max and ±.2 dB typical.