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Software-defined vehicles (SDVs) are a big theme at CES this year, shifting vehicles from hardware-centric upgrades to over the air (OTA) software upgrades. In order to do this, vehicle subsystems must rely on a, more or less, generic processing platform that can perform a wide variety of functions to serve the various aspects of a car. As shown in Figure 1, TI’s approach to this is shifting from a “domain” architecture to a “zonal” one where ECUs that were once custom-tailored to specific domains (e.g., powertrain, ADAS, infotainment, body electronic and lighting, passive safety) are now more location, or zone-, -based to reduce weighty wire harnessing and improve processor speeds. 

Figure 1 Traditional domain versus zone architecture. Source: Texas Instruments

TI’s automotive innovations are currently focused in powertrain systems; ADAS; in-vehicle infotainment (IVI); and body electronics and lighting. The recent announcements fall into the ADAS with the AWRL6844 radar sensor as well as IVI with the AM275 and AM62D processors and the class-D audio amplifier. 

The AWRL6844 radar sensor uses 60-GHz millimeter-wave (mm-wave) with a 4×4 antenna array and edge AI models running on an on-chip TI-specific accelerator and DSP to support several in-vehicle safety measures including occupancy monitoring for seat belt reminders, child presence detection, and intrusion (Figure 2). Presently, OEMs resort to a combination of in-seat weight sensors, two UWB sensors for front-row and back-row child presence detection, and an ultrasonic intrusion module for the same direct-sensing safety measures, directly tracking human activity such as respiration, heartbeat, movement, etc.). The technology is designed to assist OEMs in meeting evolving regulatory safety requirements such as the Euro new car assessment program (NCAP) advanced that offers rewards to manufacturers for implementing advanced safety technologies as a means to complement its established star rating system. Yariv Raveh, the vice president and business unit management of radar stated, “In 2025 the Euro NCAP requirement for child presence detection will only award points for a direct sensing system and in the near future, the in-cabin sensing system must accurately distinguish between a child and an adult in order to provide a good user experience.” 

Figure 2 A block diagram of TI’s AWRL6844 radar sensor and the three vehicle modes that the sensor can assist with (seat belt reminder, child presence detection, and intrusion detection). Source: Texas Instruments

Some of the features of the new AM275x-Q1 and AM62D-Q1 processors are the integration of two vector-based C7x DSP cores, multiple Arm cores, on-chip memory, an NPU accelerator, and audio networking with Ethernet AVB. The differences between the processors is highlighted in Figure 3. “Tier 1 suppliers must elect the appropriate processing components to meet all of their customer needs across their fleets. So, our answer is to provide two different architectures to give engineers the flexibility to choose across the range of use cases, all using the same audio processing family where engineers can design standalone and integrated premium audio systems across a range of performance levels with minimal additional hardware and software investment,” said Sonia Ghelani, TI’s product line manager for signal processing MCUs. The company is actively working with customers to incorporate AI into the audio signal chain for unique solutions in applications such as active noise cancellation (ANC) and road noise cancellation (RNC). 

Figure 3 The AM275x DDR-less MCU and AM62D DDR-based process for premium audio in IVI applications. Source: Texas Instruments

The TAS6754-Q1 class-D amplifier (Figure 4) is meant to assist engineers with implementing TI’s “1L” modulation scheme, a technology that lowers the inductor count per audio channel to one (hence the phrase “1L”). Modern vehicles can embed well over 20 speakers and, in an effort to reduce size, weight, and cost, class-D amplifiers are being used for their higher power efficiency and lower thermal dissipation. However, these amplifiers generally require two LC filters per audio channel to attenuate high frequency noise. “1L maintains class-D performance while reducing component count and cost, allowing the premium audio system to grow in terms of speakers and mics,” added Sonia Ghelani. 

Figure 4 Sample vehicle speaker and mic distribution as well as a sample block diagram of an audio signal chain including TI’s class-D amplifier. Source: Texas Instruments

One major discussion during the press briefing involved the industry trend of integrating ADAS and IVI functions on a single SoC. “So today we see that they’re in two separate boards, however, more and more we’re seeing that they end up being in the same board,” said Mark Ng, TI’s director of automotive systems. Sonia Ghelani added with an example of an overlap between ADAS and IVI functions, “these chimes and seat belt reminders are ADAS requirements that fall into the audio domain. As we move into a world of software-defined cars with more zonal architectures, you’ll continue to see an overlap between the two.” She continued, “For TI it’s important that we understand exactly what the customer is trying to build so that we don’t silo these systems in one bucket or another, but rather understand what problems the customer is trying to solve.” 

Aalyia Shaukat, associate editor at EDN, has worked in the design publishing industry for six years. She holds a Bachelor’s degree in electrical engineering from Rochester Institute of Technology, and has published works in major EE journals as well as trade publications.

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Figure 1 shows a variation on a sine wave oscillator, it uses just two transistors and a single variable resistor to set the frequency.

Figure 1 Just a couple of components are needed for a simple tunable sine wave oscillator.

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The section around Q1 is a multiple-feedback-bandpass-filter (MFBF). The usual embodiment of this type of filter is shown in Figure 2.

Figure 2 A standard implementation of a MFBF.

The formulas for these filter can be found in almost any textbook (where C = C1 = C2):

Please note that the center frequency, among others, is determined by the resistance of R3. The gain of the filter is determined by the ratio of R2/R1 in such a way that Av = -R2/(2*R1). Usually this filter is implemented around an operational amplifier, it can also be implemented around an inverting transistor amplifier. However, because of the limited open-loop gain of the latter, the gain will be lacking at the higher frequencies.

The section around Q2 is an inverting amplifier, with an unloaded gain set by R8/R7. D1 and D2 together with R8 form a clipper to make sure that the signal offered to the MFBF is of constant level.

At the center frequency of the filter, the phase-shift is 180°. Together with the 180° phase shift of Q2 there is a total 360° phase shift at this frequency.The loop gain is >1 due to the ample gain of Q2. Thus, Barkhausen’s criteria are met.

The relative soft clipping of D1 and D2 together with the filtering of Q1 limits the amount of harmonics in the output signal. The passive components around Q1 determine the center frequency.

With the current values, the frequency can be set between 498 Hz and 1230 Hz by changing R3 between 1k and 6k. At the same time the output amplitude changes from 1.28 Vpp to 0.68 Vpp. The output shows around ~1% distortion (Figure 3).

Figure 3 The scope image shows the oscillator output at circa 1 kHz.

A variation in the supply voltage from 9 V to 12 V causes a frequency variation of only 2 Hz and a variation of output amplitude from 0.80 Vpp to 0.86 Vpp.

Cor van Rij blew his first fuse at 10 under the close supervision of his father who promptly forbade him to ever work on the house mains again. He built his first regenerative receiver at the age of 12 and his boys bedroom was decorated with all sorts of antennas and a huge collection of disassembled radios took up every horizontal plane. He studied electronics and graduated cum laude. He worked as a data design engineer and engineering manager in the telecom industry. And is working for almost 20 years as a principal electrical design engineer, specializing in analog and RF electronics and embedded firmware. Every day is a new discovery!

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