Recently we published a calculator that provides the value of an inductor wound on a toroid given the number of turns of wire and other parameters.
A reverse calculator is provided now by SPG that calculates the number of turns needed to generate a given value of an inductor wound on a toroid. Please visit the SPG website and check under the “complementary” menu.
The inductance of a toroidal inductor can be calculated using the following simple expression: L = AL*n*n/1000 uH. AL is a constant provided by the manufacturer of the toroid and n is the number of turns of wire.. Please visit the SPG website for more technical articles and items of interest.
A recent post presented the Colpitt’s oscillator starting point with a schematic and simulation results. In addition, it also provided a link to the recent book by Ain Rehman on this oscillator available from Amazon that contains design information and an exhaustive list of references for further study for interested readers. This post suggests downloading the Colpitt’s oscillator frequency calculator from the SPG website. It provides a good starting point and sanity check on the design of a Colpitt’s oscillator for the user. Please visit the SPG website and look under the ” Complementary” menu item.
3D design and printing has been gaining momentum recently for use in various applications — from microstructures to houses. Electronic enclosures and other parts are no exception. 3D design and printing is a quick way to make enclosures and fast prototypes using many different types of materials. The image below is a lighthearted print of a dragon. Be that as it may, if you want to print using a 3D printer please contact us for a bid as well. Please visit the SPG website for more information on our capabilities in electronics, ASICs and RF/Microwave modules.
A vector modulator is a very versatile device that can be used to adjust the amplitude and phase of a RF signal. i.e it combines the functions of phase shift and attenuator. A vector modulator is a key component in 5G networks and can be used as a beamformer. It can be used in generating complex signals such as QPSK and QAM. It is also used in digital predistortion networks for RF power amplifiers. Please visit the Signal Processing Group Inc website for more technical information and articles.
tf and fT are two closely related parameters for a bipolar model. Usually the parameter tf is included in the model and fT can be calculated from it and other parameters. tf is used to model the effect of the excess charge stored in the transistor when it is biased in the forward active region. i.e. the base – emitter junction is forward biased and the base collector junction is at 0 Volts. It is needed to calculate the emitter diffusion capacitance. fT is the transistor’s unity gain bandwidth defined as the frequency where the common emitter, zero load, small signal current gain extrapolates to unity ( Ref:”Modeling the bipolar transistor”. Ian Getreu). CAD programs use many different ways to use tf to convert to fT. However, this blog simply provides a way to get the conversion done to estimate the fT from tf. This provides the engineer a quick way to see what he may be dealing with without a lot of calculator overhead. If he needs a very accurate number he can always use an expensive simulator. This simple conversion is given by: fT(max)= 1/(2*pi*tf). This simple conversion assumes a zero value for the transistor’s internal collector pad to collector pin resistance. This resistance is assumed to be very small so this expression is a good estimate. Another assumption is that this is the maximum or peak value of fT. A calculator based on this expression is available from the Signal Processing Group website for download free of charge. Please visit the SPG website for other items of interest in analog and RFMW design.
As more and more designs for RFMW circuits get done, we need a good public domain active device model of GAN devices supported by fabrication vendors and suppliers of GAN devices. This would accelerate and accentuate revenue for both the supplier and the user. In addition to this, this model needs to be implemented in a public domain application program/simulator such as QUCS. The reason is that existing simulators are much too expensive to acquire and use. The simulators like ADS and Microwave office cost an arm and a leg to use. Following on the record of SPICE II it seems that a similar trajectory needs to implemented for a RFMW simulator like QUCS.