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UP/DOWN Convertors

BASIC PRODUCT DETAILS

RF and Microwave UP/DOWN Converter:- About, Types, Application, Design:

An RF up-down converter is a subsystem used to convert a lower frequency signal to a higher frequency in the case of an up-converter and converts a high frequency to a lower frequency signal for Downconverter.

  • RF UP converters are used in the front-end of the transmitter to generate the RF signal for subsequent amplification and transmission.
  • RF Down-converters are used in front of the receiver to generate IF ( Intermediate) signal from the received signal for subsequent amplification and processing in the digital circuit.

The prime component for an Up/Down converter is an RF and Microwave Mixer. The mixer will have 2 input ports and one output port.

  • If RF and LO ( Local Oscillator) signal is fed to the mixer, IF ( Intermediate frequency ) signal will generate and it is called the down converter.
  • If an LO and IF ( Local Oscillator) signal are fed to the mixer, RF ( Signal with frequency addition of LO and IF ) signal will generate and it is called the up-converter.

The prime requirement of conversion of the RF signal to Intermediate frequencies is to use in superheterodyne radio receivers, as it is easier to make RF filters with sharply selective frequency cut off at lower fixed frequencies.

To learn more about RF and Microwave systems, we recommend you to check the following article.

To understand the RF UP/DOWN converters, we recommend understanding more about the following components, which are prime components for the construction of up & down converters by checking the respective pages.

In this RF and Microwave Up and Down Converter article, we will cover,

  • What is an RF and microwave Up/Down Converter?
  • Types of RF Up/Down Converter?
  • Applications of RF and Microwave Up/Down Converter?
  • What are the specifications that need to consider in the selection of an RF Up/Down Converter?
  • RF and microwave up/Down Converter manufacturers.

Prime features of a perfect UP/DOWN Converters:

The performance of an RF UP/Down Converter is based on the RF performance of the components used in the design of the converter. If the internal components used are of high RF characteristics, the overall feature of the converter will be better. Following are the prime features of the perfect up and Down-converter.  

  • Excellent Frequency stability over the entire band.
  • Fine-tuning steps for LO.
  • Low Phase Noise over the entire frequency of operation.
  • Gain Control option and its stability.
  • Low LO leakage and high Image rejection.
  • Small package with multichannel options.

Design and Application

RF Up-Down Converter Design concept?

For the design of the UP and DOWN converter prime component is RF and Microwave mixer.

RF mixer is a 3 port device used to mix two RF signals, which are applied to the input ports (ports 1 & 2), and generate new signals at the output port at the frequency, which is the sum and difference of the frequency provided to the mixer. 

  • RF Mixer is a nonlinear circuit component used to generate new frequencies signal from applied different frequencies to it.

For example: 

Intermediate frequency (IF) signals of 70 MHz will Mix with a high-frequency signal in C-Band to generate an output signal in C-band.

For RF DOWN CONVERTER:

For the design of RF and Microwave down converters, the prime components are a Mixer to mix the RF signal with a Local oscillator signal to generate the IF signal and Low noise amplifier (LNA) to the strength of a received signal.  

  • As any noise present on the received signal will be amplified by the device, and that leads to a higher noise figure, Low noise amplifiers are necessary for front of the mixers.

RF down converter will also have either one or two stages of mixing to reach to required IF frequency.

For RF UP CONVERTER:

For the design of RF UP converters, the prime components are an RF mixer and an amplifier with adjustable gain control.

The mixer mixes the RF signal in the time domain with a LO frequency, as a result, two frequency signals (difference and sum) are produced. Because of the double-balanced topology in the mixer, the sum-product frequency is suppressed, and the different product signal comes in the output.

Up converters are used in the transmitter path, where the IF or a base-band modulated signal feed to the mixer and that gets multiplied by an LO to produce the RF signal. The RF signal is then filtered using and band-pass filter to eliminate the unwanted spurious frequency products, and then pass through the power amplifier with adjustable gain.

  • For the power amplifiers, an important specification is the third-order intercept point (IP3) that describes the non-linear characteristics of the device. This is related to the 1dB compression point of an amplifier.

What is the difference between an RF up-converter and an RF down converter?

When converting lower frequency to a higher frequency, the system is said to up-convert, and when it converts a high frequency to intermediate frequency (Lower frequency )it is said to down-convert.

  • IF to RF conversion is called Up-converter.
  • RF to IF conversion is called Down-converter.

RF and Microwave frequency down and upconverters are used in all aspects of RF communication to radar systems. In fact, RF conversions are used anywhere that RF signals are used.

How RF Down Converter Work:

RF mixer in the up-down converter will have basically 3 ports ( 2 input and 1 output port), one port is to feed the input signal ( IF or RF) and the second port is the feed the other signal from the local oscillator. In the third port, we will get the combined or the difference of 2 input frequencies.

Design Flow:

Step 1: Select suitable RF mixers which can convert the required band to 70 MHz range or for the upconversion mixer which can generate an RF signal from the IF signal.

Step 2: Select the suitable filters, attenuators, isolators to be used at different stages of the RF up / down converter design as in the Up down converter block diagram as per link budget.

Step 3: Select the RF synthesizer (LO) which is used to feed the LO signal to the mixer to down-convert the received RF signal to IF or up-convert.

Step 4: For down converters, LNA ( Low noise amplifier ) needs to select to amplify the received signal with lower noise, which is to be placed before the mixer. For upconverter, suitable amplifiers need to select to amplify the up-converted signal before transmitting.

Step 5: Line up all the components as per the up-down converter block diagram, in such a way that the signal loss will be minimal as per the link budget for the up/down converter.

Step 6: For calculating the losses in each stage of the chain, we can use dedicated design software or a simple excel file by entering the insertion loss of each component from the respective datasheet of RF components.

Step 7: Once we selected all the components as per the block, we can assemble the entire system and terminate all the open ports, and finalize it with suitable connectors for the RF and IF ports.

Types of RF and Microwave Mixer for Converter design:

The essential characteristic of an RF mixer is that it produces an output signal, with a non-linear device, which is the product of the two input signals. RF Mixers are developed using discrete components, either as a part of integrated circuits or in a module package. There are mainly 4 types of RF mixers

· An unbalanced RF mixer:

· Single balanced RF mixer:

· Double balanced RF mixer:

· Triple balanced RF mixer:

Applications of UP/DOWN Converters:

RF Up / Down converters are mainly used in military radar, Satellite Communication systems (SATCOM), Cellular transceiver applications, ISM Band Receivers, and in 5G Point-to-Point radio communication. For the application in the SATCOM industry Up down converter comes with an integrated Power Amplifier and down converter with LNA into a single module, which is called an RF Block Up / Downconverter.

Below are the prime industrial applications.

· Point-to-Point Telecom radio Communication.

· Telemetry and tracking receivers.

· Radar and satellite communication.

· Astronomy and Meteorology.

Basics & Selection Feature

Main specifications need to consider in the selection of  UP-Down Converters.

The important parameters to consider for an RF upconverter and down converter are operating frequency, power output, conversion gain/loss, and noise figure. A wide range of RF and microwave up-down converters are available from different manufactures. The designer needs to select a converter as per the RF design requirement of the system.

Frequency of operation: 

Two frequency parameters that need to consider are,

  • IF Frequency: This is the lower frequency that the converter needs to cover. In the case of an upconverter, this is the input frequency and for a down converter, it is the output frequency.
  • RF Frequency: This is the higher frequency converter that needs to cover. In the case of an up converter, this is the output frequency and for a down converter, it is the input frequency.

The Narrowband of frequency covering will be more suitable for the operation.

Gain (dB) / Insertion loss:

The gain of an up down converter indicates the net increase in power level between the input signal and the converted output from the converter.

Insertion loss indicates the overall loss in the signal strength when signal passe through the up / down converter.

  • Conversion gain or loss is defined as the ratio of the output power to the input power of the signal.

Input intercept point (IIP3):

Input intercept point (IIP3) of RF converter, is the RF input power at which the output power of the unwanted intermodulation output signal and the desired output signal become equal. This parameter will be of amplifier used inside the upconverter. 

Isolation between the channels:

If an up-down converter has multiple channels, it is important to check the isolation between the channels. Better the isolation among the channels, better the converters.

Spurious:

Spurious of the RF converters are the undesired frequencies generated inside the mixer that may fall into the IF-band. Lower the spurious, better the specification.

Power and Dynamic Range:

The power output of a converter is the RF power level of an output signal from the converter. The dynamic range of the RF converter is the signal power range over which the up-down converter generates the desired output signal.

Noise figure (NF):

Noise figure (NF) of the RF Up/Down converter is defined as the added noise generated within the system. RF converter with a lower value is better for the application.

RF connectors:

RF up down converters can design with different types of connectors options like SMA, N-type, 3.92 type, etc   

Conclusion:

RF Down and upconverters are reliable means for converting one frequency signal to another. There are manufacturers who offer the options like multichannel, remote access, high input power, individual gain control, and packaged for airborne, military, commercial, and extreme environments usage, etc.

Below is the list of top listed RF and Microwave up and down converter manufacturers. If you would like to recommend any manufacturer feel free to recommend it to us through the contact us or manufacturer registration button on the top of this page.

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