Question 1

What is a circulator?

Accepted Answer

A. As shown in the figure, the high-frequency signal that has entered from the terminal ① is transmitted only to the terminal ②, and the high-frequency signal that has entered the terminal ② is transmitted only to the terminal ③. And the high-frequency signal that has entered the terminal ③ will be transmitted to the terminal ①. In this way, transmission takes place only in a fixed direction, and does not happen in the opposite direction.

Fig. Circulator

Question 2

What is an isolator?

Accepted Answer

A. An isolator is a product which a termination resistor is connected to any one of the terminals of the three terminals of a circulator, as shown in Fig. In this Fig., the termination resistor is connected to terminal ③. High-frequency signal that has entered from the terminal ① is transmitted to the terminal ② with minimal loss, as in the case of circulator.
But the high-frequency signal that has entered from the terminal ② is absorbed by the termination resistor connected to the terminal ③, and is almost not transmitted to ①. Ideally, the reflection from the termination resistor is ""0"", but normally there is some mismatch and the power due to the mismatch is input to the terminal ③, and is transmitted to terminal ① similarly as in the circulator.
As in the Fig., the power absorbed by the termination resistor is converted into heat and is eventually discharged to the outside (air).Usually, since the isolator is a two-terminal component, so when you look from outside it appears that the power that has entered the terminal ② is consumed in the isolator and only a small part of it is transmitted to the terminal ①.

Fig. Isolator

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Question 3

What is the difference between circulator and isolator?

Accepted Answer

A. As shown in the Fig., when a termination resistor is connected to the circulator, it will become an isolator. Generally, since there is an expression of making the circulator function as an isolator, sometimes isolator and circulator can create confusion.

Fig. Relationship between isolator and circulator

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Question 4

What kind of high-frequency products are offered by TDK?

Accepted Answer

A. TDK utilizes technology such as LTCC technology and thin film technology to offer an expansive product lineup including filters, diplexers, triplexers, baluns, directional couplers, chip antennas, isolators/circulators, and modules. This website features a product map which makes it easy to check product usage.

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Question 5

Where do you use a circulator?

Accepted Answer

A. As shown in Fig. (a), it is used in the antenna duplexer, and in combination with steep BPF it is used in branching circuits (Fig.(b)). Further, if the termination resistor built into the isolator does not meet the required standards for the reflected power, instead of using built-in termination resistor, the resistor is connected external to the circulator to use it as an isolator as shown in Fig. (c). By using the attenuator (ATT) instead of the termination resistor, it becomes a circulator with reflected power detection functionality (Fig.(d)).

Fig. (a) Used for antenna duplexer

Fig. (b) Used in branching circuit

Fig. (c) Used as an isolator, by connecting a termination resistance externally

Fig. (d) Used as a circulator with reflected power detection functionality, by connecting an attenuator (ATT) externally

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Question 6

Where do you use an isolator?

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A. Impedance matching of amplifiers and protection of the transistor used in the final stage, intermodulation prevention of synthesizer etc., it is used to remove the adverse effects caused by the reflected wave, as shown in Fig. As a result, as compared with the case of not using the isolator, the unnecessary radiation generated by the device is reduced, the circuit's operation becomes more stable ,and it could also contribute to low power consumption.

Fig. Usage example of an isolator

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Question 7

Notes on using circulator and isolator (Connected to the 50Ω line)

Accepted Answer

A. We recommend that you connect to the 50Ω line, when you use. If the terminal form is SMD and strip line, when the measured jig's substrate and the actual substrate are different, there are cases where it is not a 50Ω line.
Since it actually depends on the material and the thickness of the substrate to be used, the recommended patterns that we usually prepare are just reference information. In the actual device or environment that conforms to it, you need to make sure that the measurements obtained are same as the measured values of our company.
Also, in module products, attention is required when aerial wiring is done between the isolator's strip line terminal and other parts in the module because of the shape constraints of the terminal. Furthermore, if the width of the terminal and the width of the 50Ω line on the printed circuit board are different, it is necessary to devise some kind of a correction circuit on a printed circuit board.

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Question 8

Notes on using circulator and isolator (About permissible power)

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A. Please check the permissible power when you are using the product. Normally, the permissible power has been defined by the unmodulated continuous waves. Modulation waves and pulse waves (if ON-OFF is repeated in very short periods of time) are usually not a problem considering their average power.
However, since tolerance will vary greatly in the implementation (heat dissipation) state, care has to be taken in case of the reflected power. In the case of isolator, mostly the passing power tolerance is more than the reflected power tolerance. But if the reflected power is not enough, please contact us so that we can increase the tolerance by changing the built-in termination resistor.

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Question 9

Notes on using circulator and isolator (About the influence of the magnetic material)

Accepted Answer

A. Because a magnet is used inside circulator and isolator, if a magnetic material is brought closer, the magnetic strength (magnetic susceptibility) changes and the electrical characteristics also change. Generally cases of circulator and isolator have magnetic shields, but the magnetic shield may not be complete depending on the product.
Therefore it is necessary to avoid bringing a magnet close to it. Especially when a powerful magnet (metal magnet or the like) is brought close, the characteristic would no longer return to the original even if the magnet is taken away. Hence necessary care should be taken. In addition, it is better not to bring soft magnetic materials such as iron near. Further, the behavior of the characteristics of circulator and isolator should be well understood before using, if a magnet and soft magnetic materials have to be placed near the isolator.

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Question 10

Notes on using circulator and isolator (About the effect of temperature change)

Accepted Answer

A. Depending on the magnetic material used in circulator and isolator, the characteristics will change respectively with the temperature. Accordingly, the electrical characteristics of the circulator and isolator will also change. Therefore, even if they were operating normally at room temperature, the equipment may not work properly when the temperature is low or high.

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Question 11

Notes on using circulator and isolator (About reflow support)

Accepted Answer

A. Circulator and isolator which do not guarantee reflow support, strictly prohibit reflow. The magnetic force of the magnet may become extremely weak resulting in failure to exhibit the characteristics.

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Question 12

What are the different kinds of circulator and isolator?

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A. Circulators are roughly classified into lumped constant and distributed constant types. Distributed constant type is further classified into waveguide type, strip line Y-junction type and substrate type. Moreover, there are cases where the strip line Y-junction type is referred to as a distributed constant type. Each of the features and uses are shown in Table.

Classification		Characteristics	Primary uses
Distributed constant type	Waveguide type	Low loss Large power handling design is possible Somewhat large in shape	Microwave link Marine radar Mainly used in 3GHz or more
	Strip line Y-junction type	Small compared to waveguide type Easy broadband design	Microwave link Broadcast equipment, mobile communications based on other stations Mainly used in the UHF band or more
	Substrate type	Conform to the planar circuit Small power handling capability	Microwave link Mainly used in 1.5GHz or more
Lumped constant type		Small size, light weight Easy broadband design	Broadcast equipment, mobile communications based on other stations Mobile phone terminal Mainly used in the VHF, UHF band or more

Table Characteristics and applications of all kinds of circulators and isolators

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Question 13

Please provide details on board layout for TDK’s chip antennas.

Accepted Answer

A. TDK publishes design notes for our chip antennas. If the desired design notes are not available, please specify the desired products and then send inquiries to your nearby sales office or distributor, or send inquiries from this website. TDK will send you the appropriate file (DXF file).

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Question 14

Cannot do the board layout as specified in the data sheet; doesn't it work?

Accepted Answer

A. TDK publishes design notes for our chip antennas. If the desired design notes are not available, please specify the desired products and then send inquiries to your nearby sales office or distributor, or send inquiries from this website. TDK will send you the appropriate file (DXF file).

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Question 15

What are the specifications for the components (capacitors&#44 inductors) for matching?

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A. Please specify the desired products and then send inquiries to your nearby sales office or distributor, or send inquiries from this website. TDK will send you the appropriate file (DXF file).

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Question 16

Is it possible to use the inner layer of the layout portion of the antenna for other wiring?

Accepted Answer

A. We recommend that for areas that make up the antenna, remove all the GND layers and do not place other wiring.

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Question 17

How should the antenna and the module (IC) be connected?

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A. Please connect the characteristic impedance, designed to your board conditions, with the 50Ω transmission line.

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Question 18

Is mass production delivery possible with substrate + cable?

Accepted Answer

A. Our company delivers parts separately.

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Question 19

There are several products for the same application&#44 what is the difference?

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A. The correct installation position differs depending on the product. TDK publishes design notes and selection guides to help you select an appropriate product.

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Question 20

What is a balun?

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A. In smartphones and wireless devices such as wireless LAN, baluns convert an unbalanced signal (Unbalance) to a balanced signal (Balance), and vice versa. At the same time, it also carries out the conversion of the impedance value. Our baluns using low temperature co-fired ceramics (LTCC) are available in a wide range of products with variations in frequency, shape and size, terminal structure, specification values, and more.

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Question 21

What is the purpose of the filter?

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A. A predetermined frequency is used for communication between devices such as smartphones and wireless devices such as wireless LAN. The function of the filter is to pick up only the frequency of the required signal and to eliminate signals which are not required. Our filters using low temperature co-fired ceramics (LTCC) are available in a wide range of products with variations in frequency, shape and size, terminal structure, specification values, and more.

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Question 22

What is a directional coupler?

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A. A directional coupler - It picks up a part of the output (typically about 1/100 of power, about -20dB in dB display) to constantly maintain and control
the output gain of the power amplifier (PA), and is responsible for providing the feedback function to the input of the PA.

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Question 23

What is a diplexer?

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A. A diplexer is used in dual-band devices for smartphones and wireless devices such as wireless LAN. It is located at the entrance from the antenna, and is a filter element of the 3-port that separates the two frequency ranges of the dual-band.
TDK's diplexers are designed to achieve miniaturization and low insertion loss, while also supporting high functionality. They are also ideal for embedding in modules. Our diplexers using low temperature co-fired ceramics (LTCC) are available in a wide range of products with variations in frequency, shape and size, terminal structure, specification values, and more.

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Question 24

Please explain what is meant by the last part of the part number.

Accepted Answer

A. The latter part(-XXXX) of the part number is an indication of the individual product model number. It is not the LOT code.

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Question 25

What is the difference between duplexer and diplexer?

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A. In general in most cases, a ""Duplexer"" means the separation function of transmission and reception and the ""Diplexer"" means the band switching function of multi-band respectively.

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Question 26

What is a triplexer?

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A. A triplexer is used in triple-band devices for smartphones and wireless devices such as wireless LAN. It is located at the entrance from the antenna, and is a filter element of the 4-port that separates the three frequency ranges of the triple-band. TDK's triplexers are designed to achieve miniaturization and low insertion loss, while also supporting high functionality. They are also ideal for embedding in modules.

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Question 27

Is customized support possible?

Accepted Answer

A. If you are interested in customization of high-frequency products and modules, please specify the desired products and then send inquiries to your nearby sales office or distributor, or send inquiries from this website.

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Question 28

I want S-Parameter data.

Accepted Answer

A. If you would like S-parameters of high-frequency products and modules, please specify the desired product numbers and then send inquiries to your nearby sales office or distributor, or send inquiries from this website.

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Question 29

What are the items that represent the characteristics of circulator and isolator?

Accepted Answer

A. The three main factors of circulator and isolator are "Insertion loss (forward loss)", "Isolation (reverse direction loss)" and "V.S.W.R." as shown in Fig.
Since the circulator and isolator have a frequency characteristic, you will need to specify a particular frequency range, when you actually use it.
Circulator is evaluated by connecting a terminal resistor to 1 port and making it operate as isolator. Since the circulator is a three-fold symmetry circuit, its characteristics will be basically the same when seen from any port. However, strictly speaking, this will be slightly different. So you may have to check the characteristics of all three ports, if necessary.

Fig. Isolator characteristics example

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Question 30

The product was equipped according to the data sheet&#44 but it did not give the same performance.

Accepted Answer

A. The performance of the antenna is determined by the customer's substrate conditions (board size, mounting position, occupied area).
Performance shown in the data sheet is an example that was measured on a standard substrate, manufactured by our company.

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