NB-IoT Using Filter


Narrowband Internet of Things (NB-IoT) is a Low Power Wide Area Network (LPWAN) radio technology which developed to enable a wide range of new cellular devices and services. It works in one of three ways:

Guard bands from LTE spectrum blocks or In-bands of LTE spectrum blocks
GSM (Global System for Mobile Communications) unused 200kHz bands

According to 3GPP Releases 13, 14, and 15, the standard bands coverage in LTE-Advanced, eMTC (as called LTE-M), and EC-GSM-IoT, a full or half duplex mode. Frequencies range focused in/approx 460MHz, 700MHz, 800MHz, 900MHz, 1700MHz, 1800MHz, 1900MHz, and 2100MHz. NB-IoT devices receive bandwidth not more than 5 MHz as standard. Transmission method by SC-FDMA (uplink) and OFDMA (downlink). NB-IoT uses modulation schemes BPSK (binary phase-shift keying) and QPSK (quadrature phase-shift keying).

NB-IoT provides the following advantages to IoT networks/devices:

Lowest power consumption
It supports battery life extension by efficiently performing antenna integration and deployment is essential to this longevity.
Deeper signal penetration
It helps particular networks coverage in outdoor, indoor, and underground such as autonomous cars, smart homes, smart grids, smart drainage systems, tunnels, etc.
Network security & reliability
NB-IoT is provided with the same security measures based on LTE networks that include secure authentication, signaling protection, and data encryption enabled.
Networks scalability
IoT technology has the capability of delivering coverage to hundreds of millions of devices, plus LTE-M consideration to provide long-range wireless connectivity for devices of all kinds.

The above advantages enable NB-IoT technology to adopt by feasible applications as below:
Smart City
NB-IoT makes infrastructures of city smart, for instance, street lighting, transport, road traffic monitoring, parking spaces management, etc.
Smart Industry
NB-IoT helps connected many industrial appliances, e.g. warehouse monitoring, logistics tracking, welding machines or air compressors, etc. It also drives machines, factories, and workplaces to become more efficient, e.g. smart metering (electricity, gas, and water).
Smart Home
NB-IoT supports connected various terminals of the home in order to control, monitor and track. Examples: intruder alarms and fire alarms, waste bins, refrigerators, washing machines, dryers, toaster ovens, heating and air conditioning, lighting, audio, and video entertainment systems, location and security systems (intruder alarms and fire alarms), etc.
Smart Agriculture
Monitoring or tracking of animals, crop, soil, climate conditions, etc.
Health Care
Wearables for personal in order to health monitoring of those suffering from chronic or agerelated conditions, drug delivery.
Smart Retail
Intelligent stores, smart connected cabinets, smart shelves.

However there is no perfect technology in the world, it still has shortcomings as below. NB-IoT cellular base stations to NB-IoT devices coverage overlaps or nears other adjacent base stations such as from LTE signals will easily produce a kind of internal interference referred to as Inter-PRB (physical resource block) or in same coverage range, there are some interference issues between two different PRB elements that may collide with each other.


How to mitigate or eliminate the unwanted signal interference between NB-IoT and LTE networks or adjacent working devices in the same coverage becomes a necessity to point when designs consideration. Keeping the entire design framework in minimizing changes, adding a narrow rf band pass filter into the networks would be a nice option. The narrowband rf bandpass filter can help to suppress noises.



TEMWELL team has developed firstly narrow RF band pass filter for NB-IoT, some frequencies including UHF 460MHz, 700MHz, 868MHz, 915MHz, and VHF 146MHz, 157MHz, 160MHz, 172MHz. Bandwidth from 2 MHz to 10 MHz around. High Attenuation upon stop band you need, maximum up to 50-60dB. Package option thru-hole (pin) and connector (SMA female or N female). Power handling can support 5 to 10 Watts under this technology design (Helix). One feature of helix Bandpass Filter is that the Frequency is adjustable slightly when you are commissioning the filter on your circuit design. *How To Tuning Temwell Helix Bandpass Filter


 Specification range:
Frequency: 146M, 157M,160M,172M,460M,700M,868M,915M
Bandwidth: 2~5MHz

Filter Dimension:

4 Pole Helical Filter - TF (22.4x5.6x12.5) / TFW (22.4x5.6x8.6)

★3 Pole Helical Filter - TT (16.8x5.6x12.5) / TTW (16.8x5.6x8.6)

★2 Pole Helical Filter - TD (11.2x5.6x12.5) / TDW (11.2x5.6x8.6)

Please see the reference part number table of pin type below.

A. 2 POLE Helical Bandpass Filter

7H2 TD Series
# TEMWELL P/N Fc (MHz) B.W (MHz) Attenuation
1 TD62713D-146M 146 3 FC-30M 30db, Fc+30M 35dB
2 TD62714B-157M 157 2 FC-10M 16db, Fc+10M 21dB
3 TD62715B-160M 160 2 FC-10M 16db, Fc+10M 21dB
4 TD62716A-172M 172 2 FC-10M 14db, Fc+10M 18dB
5 TD62717A-460M 460 2 FC-30M 39db, Fc+30M 33dB
6 TD62718A-700M 700 2 FC-30M 35db, Fc+30M 30dB
7 TD62719C-868M 868 5 FC-50M 30db, Fc+50M 25dB
8 TD62720B-915M 915 5 FC-50M 40db, Fc+50M 33dB

5W2 TDW Series
# TEMWELL P/N Fc (MHz) B.W (MHz) Attenuation
1 TDW21043B-460M 460 2 FC-50M 35db, Fc+50M 41dB
2 TDW21044B-700M 700 2 FC-50M 41db, Fc+50M 31dB
3 TDW21045B-868M 868 5 FC-50M 32db, Fc+50M 28dB
4 TDW21046B-915M 915 5 FC-50M 33db, Fc+50M 27dB

B. 3 POLE Helical Bandpass Filter

7H3 TT Series
# TEMWELL P/N Fc (MHz) B.W (MHz) Attenuation
1 TT63721B-146M 146 3 FC-30M 40db, Fc+30M 45dB
2 TT63722B-157M 157 2 FC-10M 26db, Fc+10M 31dB
3 TT63723B-160M 160 2 FC-10M 26db, Fc+10M 31dB
4 TT63724A-172M 172 2 FC-10M 24db, Fc+10M 28dB
5 TT63725A-460M 460 2 FC-30M 49db, Fc+30M 43dB
6 TT63726A-700M 700 2 FC-30M 45db, Fc+30M 40dB
7 TT63727A-868M 868 5 FC-50M 40db, Fc+50M 35dB
8 TT63728A-915M 915 5 FC-50M 50db, Fc+50M 43dB

5W2 TDW Series
# TEMWELL P/N Fc (MHz) B.W (MHz) Attenuation
1 TTW31049B-460M 460 2 FC-50M 47db, Fc+50M 55dB
2 TTW31050B-700M 700 5 FC-50M 46db, Fc+50M 39dB
3 TTW31051B-868M 868 5 FC-50M 49db, Fc+50M 39dB
4 TTW31052B-915M 915 5 FC-50M 47db, Fc+50M 40dB

C. 4 POLE Helical Bandpass Filter

7H4 TF Series
# TEMWELL P/N Fc (MHz) B.W (MHz) Attenuation
1 TF64721B-146M 146 2 FC-10M 51db, Fc+10M 39dB
2 TF64722B-157M 157 2 FC-10M 54db, Fc+10M 43dB
3 TF64723B-160M 160 2 FC-10M 53db, Fc+10M 43dB
4 TF64724A-172M 172 2 FC-10M 48db, Fc+10M 37dB
5 TF64725A-460M 460 2 FC-50M 62db, Fc+50M 57dB
6 TF64726A-700M 700 2 FC-50M 64db, Fc+50M 66dB
7 TF64727A-868M 868 2 FC-50M 52db, Fc+50M 50dB
8 TF64728A-915M 915 2 FC-50M 57db, Fc+50M 52dB

5W4 TFW Series
# TEMWELL P/N Fc (MHz) B.W (MHz) Attenuation
1 TFW41049B-460M 460 2 FC-50M 52db, Fc+50M 55dB
2 TFW41050B-700M 700 2 FC-50M 61db, Fc+50M 51dB
3 TFW41051B-868M 868 2 FC-50M 62db, Fc+50M 55dB
4 TFW41052B-915M 915 5 FC-50M 58db, Fc+50M 52dB

In addition to the above standard parts, different frequency (up to 40 GHz), narrower bandwidth, higher attenuation, lower insertion loss, package (Pin, Connector, SMD), power handling (up to 200 Watt) are customizable. You maybe search the closest spec by the below link first from our current catalog. Search link If not find suitable, please be assured we have other technologies to do feasible filter for you. Whatever Notch Filter, rf low pass filters, rf high pass filters, or dielectric filter and cavity filter and so forth. Please contact us directly or send us your required rf filter specifications.

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