Silicon Labs recently introduced the Si484x AM/FM/SW receiver family to meet the needs of the ATDD radio market. The Si484x family is based on a digital low-IF architecture that provides a full radio from a very simple antenna interface to L/R analog audio out. The Si484x ICs feature a built-in ADC that can directly interpret the analog tuning of the wheel to frequency changes while providing I2C-compatible 2-wire control to a combined MCU and LED/LCD driver.
Unlike a traditional analog IC that cannot output the tuned frequency, the Si484x outputs the actual tuned frequency and supports indicators for valid stations and mono/stereo signals to display on the LCD/LED. The Si484x provides digital volume control, soft mute and bass/treble audio enhancements. Additionally, it offers audio conditioning for all signal environments, removing pops, clicks and loud static in variable signal conditions.
Figure 4. Si484x multi-band radio IC architecture.
New ATDD radios using solutions, as shown in Figure 4, bring several important benefits of modern digital radios to this traditional analog market. Let’s examine each of these benefits.
Reduced BOM and labor costs: Compared to traditional analog radio ICs, the integrated Si484x solution reduces BOM cost by more than 70 percent. In contrast, traditional solutions require several steps of manual tuning and testing, which increases labor cost and manufacturing time. The Si484x requires no manual tuning and needs only a single test of RF to analog. Compared to click-wheel radio solutions, the Si484x eliminates the need for the encoder while providing the advanced features comparable to click-wheel radio designs.
Superior RF performance: The selectivity parameter of a radio determines how well it can detect a target radio station in the presence of many other radio stations, a common scenario in crowded cities. Traditional analog radios use a wide channel filter with 800 kHz to 1 MHz bandwidth for FM band, which means radio stations within this bandwidth will interfere with one another and degrade the sound quality of the desired station. The Si484x radio ICs have a digital selectivity filter with narrow bandwidth that enables reception of the targeted station even in the presence of 50 dB stronger interfering radio stations as close as 200 kHz away. Figure 5 presents the Si484x family’s selectivity compared to traditional solutions. The selectivity value shown in Figure 5 is the minimum amount of delta required for blockers to interfere with the reception of the desired signal.
Figure 5. Si484x selectivity compared to traditional analog ICs.
Accurate tuned frequency display: Traditional ATDD solutions use frequency counter ICs to approximate the tuned frequency of legacy analog ICs. This can frequently lead to the actual tuned frequency being significantly different than the displayed frequency, resulting in a poor user experience. The Si484x tuning experience is precise.
Easy to design and build: Digital-based solutions are more highly integrated than traditional analog solutions, and therefore generally easier to design onto the printed circuit board. For example, the Si484x family’s digital architecture supports a small front-end matching network, voltage supply isolation and functional configuration. The architecture is implemented on a single-layer board, resulting in a simple system BOM. There are no manually-tuned parts, allowing manufacturers to eliminate labor involved with manual placement, testing and tweaking from their assembly lines.
Global competition in the radio market challenges radio system designers to consider all factors in their wheel-tuned, digital-display radio designs including RF performance, BOM cost and manufacturing flow. By using highly integrated multi-band radio receiver ICs, radio manufacturers can significantly reduce BOM and manufacturing costs while designing radio products with differentiated features that will stand out in today’s radio market.
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About the Author Natalian Zhai, Broadcast Audio Product Marketing Manager, Silicon Labs
Natalian Zhai, Sr. product marketing manager for Silicon Lab’s Broadcast Audio products, manages the multi-band radio product line for the company’s consumer electronics (CE) business. Ms. Zhai joined Silicon Labs in 2003, initially serving as a business manager and senior technical sales engineer in the company’s sales department, responsible for product lines in the Asia market. Later she moved into marketing and managed the Si470x FM receiver product line for the handset and portable media player (PMP) business. Prior to her work at Silicon Labs, she studied at Rice University (Houston, Texas) where she obtained master’s degrees in Electrical Engineering and Business Administration. She also holds a Bachelor of Science in Electrical Engineering from the Beijing Institute of Technology.
I never got into amateur radio, it was radio control that interested me initially, then electronic music, then pro audio, then microprocessors.
Kids today might be interested in making remote-controlled gadgets, especially if they can connect to their phone or PC, and control from that wirelessly.
Everyone has wireless data with phones and wifi networks and wii, but local small-scale control of toys is pretty thrilling stuff when you have built it yourself!
As we all know, with a proper hobby, it is the journey as much as the arrival!
The radio described here is still a digitally tuned radio, except that an encoder input is used instead of up and down buttons. It still tunes in steps instead of continuous tuning, which renders it unsuitable for other than broadcast channel listening.
The comparisons to prior full analog radios are way off in the negative remarks, except they would apply to the minimum cost, bottom level radios. Many of the earlier generation linear circuit receivers delivered performance far exceeding anything that this IC could ever even possibly provide, all without a single digital component. From the description given, the primary benefit of using this particular device is that it is much cheaper than any other way of making a radio.
An article describing the benefits and capabilities of a device could be interesting and worthwhile, but disparaging previous technology, and comparing it's performance to cheap junk does not add to the value of this article at all.
how do design a simple radio? This is just another article pushing a chip of course with no useful design content. Why not just title it with si-labs and say you can make a simple to design radio with the chip?
The problem with all these silicon radio chips is that the support is rubbish/zero if you are less than 500k units pa. So if you are not designing a mass market product you have little differentiation...everyone is the same.
And you can't do anything that is not obvious in the datasheet.
If you run into a problem (say sensitivity due to an interaction with your input circuit) you often have no clue what is in the chip and nobody will take the time to talk to you for your small 50k business.
So designing with discrete parts and multiple ICs will always be required for products that are not mass market and want to differentiate.
And what happens when you want to get hold of signal to do something other than AM in the MW band, or FM in the VHF band.....its all locked inside.
My first radio, 40 years ago (I was 10) was a Reflex type 3 transistors. But the selectivity was very bad. So I made a superheterodyne a few months later with 4 transistors (2xBF194 + 2xBC148). Nothing fancy but very good working for MW and LW. The only trick was to adjust properly the padding and trimmers of the double variable varable capacitor.
These were good times when I became Ham Radio. I am still, having fun with high power tubes, but young guys do not even know what a tetrode is....
My "simple design" for an Internet radio was to dedicate a PC to my audio/TV system. I got a slim design, designed to be mounted vertically or horizontally, and it looks just like any other stereo system component when mounted horizontally.
Its monitor is the HDTV set (which has an RGB input, as well as HDMI, and I use RGB). PC audio, via mini-phone plug, goes to the stereo preamp, amp, speakers. Keyboard and mouse are wireless. Broadband Internet connection is 802.11n (wireless). There you go.
You can listen to any streaming radio or watch any streaming TV, sound is great, image is great, and you have complete flexibility.
Once you've set up your favorites, with the wireless keyboard, all the radio or TV "tuning" can be done with the mouse only. No more difficult than using a typical TV remote. Drag it on the couch next to you. Piece of cake.
I've pretty much stopped using SW, ever since important broadcasters like the BBC have dropped off the air(except in transmissions to Africa), preferring to stream over the Internet instead.
However, even SW could experience a decent revival, if it would start using something like DRM (digital radio mondiale) to improve its quality. DRM is already set up to operate over the SW band. HD Radio could easily be upgraded to do the same thing.
You would be astonished at the audio quality difference between analog AM and HD Radio transnmitted over the AM band. Even for voice programs. Like night and day.
I can no longer get interested in any radio that doesn't include digital reception. In fact, I can't figure out what's keeping analog-only radios on the market. Almost makes me think that the vendors are in bed with satellite radio providers, trying to get people hooked on yet another monthly fee, instead of introducing people to digital terrestrial radio the easy way. With the US system, which operates over the existing AM and FM bands, it's a complete no-brainer.
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