RADITEK offers free running Dielectric Resonant Oscillators (DRO) as well as Phase Locked (PLO or PLDRO) and synthesized oscillators (RSPLO).

In the PLO circuit design stage, we often need to characterize the designed PLL response in the linear operating region as well as the non-liner operating region.

The Phase Locked loop (PLL) works in the linear operating region when it is locked to a reference frequency usually less than 1GHz. The most comprehensive test method to measure the PLL response/phase noise, in the PLL linear operating region is the phase noise measurement on a low phase noise/spurious spectrum analyzer, with high dynamic range.

There are also the non-linear operating characteristics to be considered. A PLL needs to change its output frequency and during the fast signal transition, the PLL goes temporarily non-linear. Such RF transientsshort term characteristics are known as lockup time. Most digital communication systems require fast frequency switching because of any available time slot for carrier acquisition gets smaller. The requirement of lock up time is about 10microseconds and below. So we need faster sampling rates to maintain sufficient frequency or phase resolution. A frequency synthesizer may need to cover increase bandwidth, in a given communication system.

RADITEK can design to any custom requirement, of extreme environment and frequency/phase noise requirement. Plus fast switching and other special requirements if needed.

A radio frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency signal into a higher power signal. Typically, RF power amplifiers drive the antenna of a transmitter. Design goals often include gain, power output, bandwidth, power efficiency, linearity (low signal compression at rated output), input and output impedance matching, and heat dissipation.

Many modern RF amplifiers operate in different modes, called classes, to help achieve their design goals. Some classes are class A, class B, class C and class E. Class D amplifiers are rarely used for RF purposes because they need even higher frequency devices.

Modern RF power amplifiers use solid-state devices such as bipolar junction transistors and MOSFETs.

Applications for RF Amplifiers:

Amplifier applications include electromagnetic compatibility (EMC) testing, defense components, communications testing and medical diagnostics. RF power amplifiers can be used in driving to another high power source and microwave heating. They can also be used driving a transmitting antenna, where the transmitter–receivers are used for voice and data communications as well as for weather sensing. Microwave or RF heating is used in industrial applications as well as in microwave ovens. Also, particle accelerators use RF sources.

Choosing the Right RF Amplifier:

When looking for the right RF amplifier, you can filter the results by the required category with the following types of RF Amplifiers:

• CATV

• Gain Blocks

• RF Low Noise

• RF Low Power

• RF Power Amplifiers

Once you choose the RF amplifier category, you can narrow them down by various attributes: by frequency range, supply current, supply voltage and packaging type to name a few. You will be able to find the right RF amplifier for your RF amplifier circuit or IC, cable TV amplifier, linear radio frequency amplifier, MOSFET RF amplifier, solid state RF amplifier, video amplifier or TV RF amplifier using these filters.

Directivity (active directivity) is defined as the difference between isolation and forward gain in dB. It is an indication of the isolationof the source from the load, or how much the load impedance affects the input impedance and the source impedance affects the output impedance. The higher the active directivity (in dB), the better the isolation.

Dynamic range is the power range over which an amplifier provides useful linear operation, with the lower limit dependent on the noise figure and the upper level a function of the 1 dB compression point.

Gain flatness indicates the variation of an amplifier’s gain characteristic over the full frequency response range at a given temperature expressed in ±dB. The value is obtained by taking the difference between maximum and minimum gain, and dividing it.

Gain (forward gain, G) for RF amplifiers is the ratio of output power to input power, specified in the small-signal linear gain region, with a signal applied at the input. Gain in dB is defined as G (dB) = 10 log10G.

Harmonic distortion is produced by non-linearity in the amplifier, and appears in the form of output signal frequencies at integral multiples of the input signal frequency. Because harmonic distortion is influenced by input power level it is generally specified in terms of the relative level for the harmonics to the fundamental signal power.

Isolation is the ratio of the power applied to the output of the amplifier to the resulting power measured at the input of the amplifier.

Linearity of an amplifier signifies how well its output power can be represented by a linear function of the input power. A linear amplifier produces at its output an amplified replica of the input signal with negligible generation of harmonic or intermodulation distortion.

Maximum signal level refers to the largest CW or pulse RF signal that can be safely applied to an amplifier’s input. Exceeding the specified limit can result in permanent noise figure degradation, increased distortion, gain reduction, and/or amplifier burnout. Noise factor is the ratio of signal-to-noise power ratio at an amplifier’s input to the signal-to-noise power ratio at the output.

Noise figure NF in dB is related to noise factor F by NF = 10 log10F in dB.

Return loss (RL) is the ratio of reflected power to incident power at an RF port of an amplifier, expressed in dB as RL = -20 log |ρ|, where ρ= voltage reflection coefficient Stability of an amplifier is an indication of how immune it is to self-oscillation, so that it does not generate a signal at its output without an applied input. A commonly used indicator of stability is the k-factor. A k-factor of 1.0 is the boundary condition for unconditional stability. If it is greater than zero but less than 1.0 the amplifier is only conditionally stable.

A Diplexer separates two different frequency bands in the receive path and combines them in the transmit path. These frequency bands usually will be wide apart in frequency domain for diplexer to work satisfactorily. It is often referred as a RF power combiner/divider with added functionality of filtering. Broadband Filters are used to pass appropriate bands in the Tx and Rx path.

Examples:

A diplexer is used to separate/combine frequency bands of GSM900 and DCS 1800 systems. It is also used in multiband design of mobile handset with multiple technologies GSM,CDMA,LTE. A diplexer does multiplexing and demultiplexing of wide frequency bands with a large enough difference.

There are two RF ports in a diplexer other than the output port, the device RF triplexer will have 3 ports other than one output port.

A duplexer is a device that allows the use of the single antenna by both transmitter and receiver. In other words a duplexer is a device which couples the transmitter and receiver to the antenna while producing isolation between transmitter and receiver. There are two types of duplexer, one by using PIN diode switches and the other using circulators. Both transmit and receive paths usually will have frequency bands very close, hence narrow band filters are used to separate these frequencies. A Duplexer is often referred as 3-port RF circulator.

Example:

It separates an uplink (890-915MHz,Uplink-UL) and downlink (935-960MHz,Downlink-DL) frequency bands in GSM900 system.

Low Noise Block Downconverter

Have you ever wondered what is an LNB and what is an LNB LO frequency?

The abbreviation LNB stands for “Low Noise Block doawnconverter”. It is the device on the front of a satellite dish that receives the very low level microwave signal from the satellite, amplifies it, changes the signal frequency band to a lower frequency band and sends it down the cable to the indoor receiver, demodulator/modem.

The expression low noise refers the quality of the first stage input amplifier transistor. The quality is measured by its Noise Temperature, Noise Figure or Noise Factor. Both Noise Figure and Noise Factor may be converted into Noise Temperature. The lower the Noise Temperature the better. So an LNB with Noise Temperature = 100K is twice as good as one with 200K. C band LNBs tend have the lowest noise temperature performance while Ka LNBs have the highest (worst).

The expression “Block” refers to the conversion of a block of microwave frequencies as received from the satellite being down-converted to a lower (block) range of frequencies in the cable to the receiver. Satellites broadcast mainly in the range 4 to 12 to 21 GHz.

Multi-LNBs

If both input probes have their own LNB amplifiers etc you have effectively two LNBs in the same module, which will have two output cables, one for each polarisation. Many variants on this theme exist, with options also for multiple bands. Such a “Quad LNB” might thus have 4 outputs, for each polarisation and each of two bands. Such an arrangement is attractive for a block of flats, head end antenna, which need to feed multiple indoor satellite TV receivers with the viewers all wanting all permutations of the two polarisations and two frequency bands.

LNB Frequency Stability

All LNBs used for satellite TV reception use dielectric resonator stabilised local oscillators. The DRO is just a pellet of material which resonates at the required frequency. Compared with quartz crystal a DRO is relatively unstable with temperature and frequency accuracies may be +/- 250 kHz to as much as +/- 2 MHz at Ku band. This variation includes both the initial value plus variations of temperature over the full extremes of the operating range. Fortunately most TV carriers are quite wide bandwidth (like 27 MHz) so even with 2 MHz error the indoor receiver will successfully tune the carrier and capture it within the automatic frequency control capture range.

If you want the LNB for the reception of narrow carriers, say 50 kHz wide, you have a problem since the indoor receiver may not find the carrier at all or may even find the wrong one. In which case you need a rather clever receiver that will sweep slowly over a range like +/- 2 MHz searching for the carrier and trying to recognise it before locking on to it. Alternatively it is possible to buy Phase Lock Loop LNBs which have far better frequency accuracy. Such PLL LNBs have in internal crystal oscillator or rely on an external 10 MHz reference signal sent up the cable by the indoor receiver. PLL LNBs are more expensive. The benefit of using an external reference PLL LNB is that the indoor reference oscillator is easier to maintain at a stable constant temperature. Ka band LNBs operate at such high frequency that they can need phase look loop frequency control unless the wanted carriers are very large bandwidth. An internal PLL uses a crystal oscillator in the LNB. An external reference PLL uses a 10 MHz reference supply from the customer’s indoor modem or receiver.

LNB Supply Voltages

The DC voltage power supply is fed up the cable to the LNB. Often by altering this voltage it is possible to change the polarization or, less commonly, the frequency band. Voltages are normally 13 volts or 19 volts.

Perfect weatherproofing of the outdoor connector is essential, otherwise corrosion is rapid. Note that both the inner and outer conductors must make really good electrical contact. High resistance can cause the LNB to switch permanently into the low voltage state. Very peculiar effects can occur if there poor connections amongst multiple cables to say an LNB and to a transmit BUC module as the go and return DC supplies may become mixed up and the wrong voltage applied across the various items. The electrical connections at the antennas between the LNB and the BUC chassis are often indeterminate and depend of screws in waveguide flanges etc. Earth loop currents may also be a problem – it is possible to find 50 Hz or 60 Hz mains currents on the outer conductors – so be careful. Such stray currents and induced RF fields from nearby transmitters and cell phones may interfere with the wanted signals inside the cables. The quality and smoothing of the the DC supplies used for the LNBs is important.

LNB Transmit Reject Filter

Some LNBs incorporate a receive band pass, transmit band reject filter at the front end. This provides both good image reject response for the receive function but also protects the LNB from spurious energy from the transmitter, which may destroy the LNB.

A Frequency source for Satellite Communications, for example.

A dielectric resonator is a piece of dielectric (nonconductive) material, usually ceramic, that is designed to function as a resonator for radio waves, generally in the microwave and millimeter wave bands. The microwaves are confined inside the resonator material by the abrupt change in permittivity at the surface, and bounce back and forth between the sides. At certain frequencies, the resonant frequencies, the microwaves form standing waves in the resonator, oscillating with large amplitudes. Dielectric resonators generally consist of a “puck” of ceramic that has a large dielectric constant and a low dissipation factor. The resonant frequency is determined by the overall physical dimensions of the resonator and the dielectric constant of the material.

Dielectric resonators function similarly to cavity resonators, hollow metal boxes that are also widely used as resonators at microwave frequencies, except that the radio waves are reflected by the large change in permittivity rather than by the conductivity of metal. At millimeter wave frequencies, metal surfaces become lossy reflectors, so dielectric resonators are used at these frequencies. Dielectric resonators’ main use is in millimeter-wave electronic oscillators (dielectric resonator oscillator, DRO) to control the frequency of the radio waves generated. They are also used as bandpass filters as well as antennas.

Design Considerations for An Oscillator

Although dielectric resonators display many similarities to resonant metal cavities, there is one important difference between the two: while the electric and magnetic fields are zero outside the walls of the metal cavity (i.e. open circuit boundary conditions are fully satisfied), these fields are not zero outside the dielectric walls of the resonator (i.e. open circuit boundary conditions are approximately satisfied). Even so, electric and magnetic fields decay from their maximum values considerably when they are away from the resonator walls. Most of the energy is stored in the resonator at a given resonant frequency for a sufficiently high dielectric constant. Dielectric resonators can exhibit extremely high Q factor that is comparable to a metal walled cavity.

There are three types of resonant modes that can be excited in dielectric resonators: transverse electric (TE), transverse magnetic (TM) or hybrid electromagnetic (HEM) modes. Theoretically, there is an infinite number of modes in each of the three groups, and desired mode is usually selected based on the application requirements. Generally, the best mode is used in most non-radiating applications, but other modes can have certain advantages for specific applications

However, since a dielectric resonator is usually enclosed in a conducting cavity for most applications, the real resonant frequencies are different from the one calculated above. As conducting walls of the enclosing cavity approach the resonator, change in boundary conditions and field containment start to affect resonant frequencies. The size and type of the material encapsulating the cavity can drastically impact the performance of the resonant circuit. This phenomenon can be explained using cavity perturbation theory. If a resonator is enclosed in a metallic cavity, resonant frequencies change in following fashion:

• if the stored energy of the displaced field is mostly electric, its resonant frequency will decrease;

• if the stored energy of the displaced field is mostly magnetic, its resonant frequency will increase. This happens to be the case for the mode.

The most common problem exhibited by dielectric resonator circuits is their sensitivity to temperature variation and mechanical vibrations. Even though recent improvements in materials science and manufacturing mitigated some of these issues, compensating techniques still may be required to stabilize the circuit performance over temperature and frequency.

The SSPA finds its use in assorted applications including airborne, radar, missile, and communications. Moreover, these diverse equipment’s work together to meet the need for today’s cutting-edge technology for designing the SSPA.

The high performance, cost effectiveness and reliability of the Raditek SSPA range covering 100KHz to 100GHz. Our SSPA designs utilize Gallium Arsenide andGallium Nitride powerdevices.

An amplifier is an electronic device that increases power of a signal. Amplifiers use energy from a power supply to increase the output signal to match input signal with large amplification. Thus the output signal becomes stronger than the input signal. Amplifiers are integral part of most electronic equipment.

Characteristics of Ideal Amplifiers

• Amplifiers gain should remain constant with changing input signal.

• Frequency should not influence the amplifier gain. All signal frequencies should amplify by same value.

• There should be no noise in the output signal.

• Removing of noise in the input signal is necessary.

When the output signal of oscillators is in a locked phase with reference signal, the resulting system acquires the form of a Phase Locked Oscillator (PLO).

These PLO provide a stabilized frequency in communication channels. These components act as signal modems and reconstruct or generate signal with low noise by multiplication of signal. Some oscillators use sampling phase detecting technique andIts design incorporates enhanced parallel feedback technology and a high quality dielectric resonator to achieving low phase noise and small frequency variation for temperature.

Oscillators find their use in wireless communication with Frequency Modulation (FM) and Amplitude Modulation (AM). Their main application is in digital data transmission but their use is widespread in analog signals as well, such as I.Cs in discrete circuits.

A PLO requires a certain period to lock on the frequency of incoming analog signals. High quality oscillator components always meet following benchmarks: superior phase noise performance, frequency generation, improvement of performance and smart Integration. Quality checks include power supply noise and impedance of load to ensure design that undergoes successful integration with the system.

The phase lock oscillators are quintessential in modern telecommunication and are widely put to use in an assortment of industries. They come in varying designs and functionalities to serve particular purposes.

A control mechanism generates an output signal phase, whose phase is as input signal is specified as a phase locked oscillator. They include circuitrycontaining a phase detector and the variable frequency oscillator.

A phase locked Oscillator is a voltage or current driven circuit that constantly regulates the phase (and thus lock), the frequency and the input signals. In addition to keeping the frequency stabilized in a communication channel, an oscillator can modulate-demodulate the signal, generate signal, and reconstruct the signal with less noise by multiplying or dividing the signal.

Uses of Phase lock Oscillators

Wireless communication use of oscillators, in carrying the signals using FM (frequency modulation) and AM (amplitude modulation). The oscillator is not only useful for digital data transmission but is also equally effective for analog signals, since, it requires a certain period to lock on the frequency of incoming analog signals. Amplifiers act as another application of oscillators. Specifically, solid-state power amplifiers (SSPA) use electric field transistors to produce the useful amplifications at gigahertz. Microwave 101 is the best example of solid-state power amplifier.

The abbreviation SSPA unfolds as Solid State Power Amplifier, which uses field-effect transistors in order to provide necessary amplification at Gigahertz frequencies. They also utilize Gallium Nitride and Gallium Arsenide devices for High Power amplification.

The amplifier comprises two broad categories depending on power:

• Low power driver section

• High power output stages

The applications of SSPA account for its superiority for High power (HPA). The factors like linearity, efficiency, and spectral re-growth and efficiency are enhanced by our superior design.

Efficient and compact solid state power amplifiers are available from Raditek from 100 KHz to 100GHz including the HF bands from 1.5 to 30MHz, with 100 watt to 15KW Output power models.

These amplifiers function as high grade linear amplifiers. Their special feature includes Harmonic Suppression filters, on-chip temperature compensation and microprocessors controls.

These amplifiers have RF, microwave, and millimeter wave applications. Solid State Power amplifiers have wide range of both the linear and saturate applications offering both CW and Pulse Models. They include communications systems like network infrastructure, radar, measurement and test.

The industrial, scientific, and medical radio band refers to a group of radio bands or parts of the radio spectrum that are internationally reserved for the use of radio frequency (RF) energy intended for scientific, medical and industrial requirements rather than for communications.

Uses include Defense, space, electronic warfare, navigation and radar systems. Medium power amplifiers have design for WLAN and other applications

Raditek RF Amplifiers are used extensively for Medical Applications such as soft tissue surgery as radio frequency ablation (RFA) and magnetic resonance imaging (MRI).

Radio frequencies are now being used increasingly, the demand for efficient, powerful, and above all, precise RF amplifiers increases.

We engineer all the requirements of these crucial applications, and our technology is currently being utilized throughout the medical and scientific community. Including Medical Labs, Plasma Physics, Original Equipment Manufacturing (OEM), and Electromagnetic Compatibility (EMC).

Telecom systems have usage and prominence in almost every industry to establish a wide and high reliability uninterrupted network of communication. Wide ranges of VSAT (very small aperture terminal) network equipment are responsible for serving the distinctive need of satellite communication for users both at business and home. A part of these systems are low noise block downconverter that receives satellite signal for the end users.

Role of Low-Noise Block Downconverter

Popular with names like low noise converters (LNC) or low noise block downconverter (LNB); they combinesa low-noise amplifier and frequencydown converter together. These are typically mounted at the focal point of Satcom and TVRO antennas and play a crucial role collecting radio waves from the dish. The major functionalities of this downconverter include as below:

• It receives the lowest levels of microwave signals from satellite

• Amplifies the signals

• Transforms the microwave signals to the L Band for feeding to the TV Set Top Box or demodulator

• LNBs cover all Satcom bands

Some of the most popular are –

• C-Band – This type of downconverter has a local oscillator of 5.15 GHz, while its frequency ranges from 3.4 – 4.2 GHz.

• Ku-Band –  Being a standard LNB of North America, it contains a 10.75 GHz local oscillator and its frequency varies from 11.7 – 12.2 GHz.

• Dual band – The LNBs of Ku band generally uses two alternatives of local oscillators including 9.75 and 10.6 GHz. It allows you to download frequencies ranging from 10.7 -11.7 GHz.