Programmable signal generators. “These signal generators are where we stand currently and I think, with the kind of advancements that are happening in the field-programmable gate arrays (FPGAs), there is a lot of functionality that gets added to the signal generators in a way that they can generate or simulate different scenarios,” believes Mohanram.
In the past, FPGA was a way of incorporating your own intellectual property (IP) into any system as it is programmable. With this, you get great performance and at the same time have your functionality implemented. He adds, “FPGAs moved into the signal generators around a year or a year-and-a-half ago, which I believe is a significant move that has occurred whereby the functionality of signal generators has grown by leaps and bounds.”
New technologies that benefit the engineer. The functionality that gets into today’s designs is very much defined in software, which is a challenge faced by most of the design engineers today. As software evolves, being able to set different types of scenarios becomes very difficult. Earlier it was very simple because you could give a square or a sine wave at the input and see how the response was on the other side. But today the algorithms that are implemented over these devices also change in real time.
Citing an example, Mohanram says, “Consider an adaptive noise cancellation system. In such a system, when you give a certain input, the output will not be the same but it will vary based on the ambiance. For you to check that, the ambiance needs to be simulated first and then the actual input signal. The actual signal is simple but the ambiance is pretty dynamic in nature. One has to basically frame the mathematical model of ambiance and get that to run.”
These kind of things were never possible but, with the arrival of programmable signal generators, these have become possible because the model can be hard coded into the hardware. and it gets implemented in real time, unlike the earlier generation where if implemented in software would result in lags and inconsistencies. Hence, it provides design engineers the capability to comprehensively test the functionality, say, build better quality products for the market.
“Also, today’s signal generators have two outputs on a single instrument,” informs Madhukar Tripathi, regional manager, Anritsu India Pvt Ltd. He says, “This is very good for many applications where usage of two instruments and syncing them is necessary. Two-channel concept has eliminated the need for a second instrument, hence cost has receded, which leads to more accurate and faster measurements.”
Design engineers can now use these signal generators and make faster and accurate measurements. Local oscillator (LO) is now more stabilised, and this provides high performance and accurate measurement for many mission-critical measurements.
Talking about the architectures used in signal generators and how they help a design engineer, Manish Joshi, deputy CEO, Scientech Technologies Pvt Ltd informs, “In signal generators, for lower frequencies, DDS-based architecture is used as it is lower in cost and best in performance as compared to conventional discrete-based approach. For a higher frequency application like wireless communication, more than one channel is used with software connectivity for downloading different waveforms based on wireless communication standards.”
He further adds, “It will help a design engineer to get smooth and high-frequency resolution signal and to design him/her own customised signal.
Programmable versus basic signal generators
“Signal/function generator with software allows a user to easily create his own waveform and edit and download complex waveforms using the wave editor, whereas with the basic signal generators the user can access only factory-defined waveforms,” informs Joshi.
The basic signal generators are still being used for primitive tests that are being conducted on some of the electronic components that are designed, but when it comes to the high-speed verification/validation or the high-speed manufacturing and testing, the days of the stand-alone box-type signal generators are gone, believes Mohanram.
T. Anand, principal consultant, Knewron, says, “The buzzword now is programmable; hardcoded or fixed physical signal generation is thing of past. More so, it is need of today’s technologically evolved world.” On another note, Tripathi believes, “Industry looks for physical signal generators as they are popular. But both categories have own merits and final decision is made based on performance, application, cost and ease of operation.”
New initiatives to help design and test better
FPGA-based instruments. From signal generators’ standpoint, there are a lot of people developing and working on specific IPs that can be implemented on the FPGA and the signal generator, shares Mohanram. He says, “There is a good level of standardisation of these IPs, and hopefully we will be able to leverage all of these across platforms of signal generators. There are different vendors having different FPGAs on their signal generators; some of them are ‘open’ and some of them are not.”