Over Temperature Effects of Gm_critical | A Technical Review

The emergence of the IoT has accelerated the trend towards lower power consumption on many MCU and RF chipsets, pressuring IC designers to wring out every bit of energy savings in their circuits. The consequence, pertaining to the clocking scheme, is usually a weaker oscillator loop amplifier starved of transconductance (gm). The reduced power consumption has the potential to severely affect analog circuits, such as the Pierce oscillator.

The Pierce oscillator driving quartz crystals is one of the most common circuits in the electronics industry. Present in almost every microcontroller, RF chipsets, and many other IC’s, this circuit is the true workhorse of timing in almost every device developed today. As most design engineers employ negative resistance analysis to assess closed-loop dynamics, some may ignore another very significant metric – gm_critical.

As the name implies, gm_critical can be defined as the level of critical value of closed-loop transconductance mandatory to keep the amplifier in linear region, while maintaining sufficient forward gain at the desired phase shift of (n*2π). The closed-loop overall gain margin (GM) is mathematically represented as:

GM = gm / gm_critical ………. (1)

Whereas; gm = oscillator loop amplifier’s intrinsic transconductance (µA/V, or mA/V)
gm_critical = closed-loop transconductance needed to keep the amplifier in linear region with sufficient forward gain at the desired phase shift (µA/V, or mA/V)

It is a well-established industry figure of merit to target GM > 5, with minimum value of 3. With the reduction in the intrinsic gm value, it is paramount to simultaneously reduce the gm_critical needed for sustained oscillations.

It should be noted that gm_critical has significant dependence on the external resonator’s electrical characteristics at the desired resonant frequency and is outlined in equation (2).

gm_critical = 4 * ESR * (2πF)2 * (C0 + CL)2 ………… (2)

From equation (2) it is evident that any significant reduction in gm must be counter-balanced with a reduction in gm_critical to ensure that the closed-loop overall margin (GM) remains the same. For instance, consider the following example:

gm = 2.7 µA/V; GM = 5; then gm_critical = 0.54 µA/V maximum
Now, if the gm is reduced to 1.0 µA/V, to keep GM = 5; the gm_critical = 0.20 µA/V maximum

In equation (2) the three critical parameters that determine the feasibility of this counter-balance are the ESR, C0 and CL of the Quartz Crystal. To achieve lower gm_critical, all three of these parameters must be simultaneously reduced to ensure proper overall gain margin (GM), while the oscillator amplifier’s transconductance gm is lowered.

As the power optimized silicon expands its domination of the electronic industry, reducing the intrinsic gm, the gm_critical metric is the most important criteria to ensure robust oscillator loop performance.

Abracon’s family of newly released Performance Optimized IoT Crystals have been engineered to specifically address the falling transconductance values across the industry and are compatible with industry’s lowest gm_critical designs. The ABM8W/ABM10W/ABM11W/ABM12W MHz series are guaranteed to operate with gm_critical as low as 3.55mA/V for 50MHz operation. The ABS06W/ABS07W 32.768kHz Tuning Fork Crystals are guaranteed to operate with industry lowest gm_critical value of 0.276µA/V @ 25°C in 2.0×1.2×0.6mm and 0.191µA/V @ 25°C in 3.2×1.5×0.9mm packages.

Plots A and B represent over extended temperature oscillation sustainability matrix of these state-of-the art 32.768kHz solutions ideally suited for energy saving RTC applications.

As transconductance (gm) of most Pierce oscillators dive to unprecedented low levels, quartz crystals have to adapt to maintain sustainable oscillations. Abracon has embraced and overcome this challenge by designing and producing, lower plating load capacitance (CL) and lower equivalent series resistance (ESR) Crystals, while simultaneously lowering the (electrode package) capacitance C0.

Meeting the lowest gm_critical requirements demanded by energy saving MCUs and RF chipsets means guaranteed low CL, ESR and C0. Abracon’s specialized design and processing techniques address this paradigm shift and brings both MHz and kHz Performance Optimized Quartz Crystals to the market. Uniquely engineered for the IoT/Wearable/Consumer Electronics market, these crystals are ready for the future of lower power engineering.

Abracon announces new IoT optimized quartz crystal series with the lowest CL and lowest ESR available on the market

Austin, TX – Abracon, LLC (Abracon), the Heartbeat of the IoT™, announces the ABM8W, ABM10W, ABM11W, ABM12W, ABS07W, ABS06W series; the industry’s leading family of quartz crystals. This series combines the world’s lowest CL and lowest ESR available for energy saving processors, MCUs, RF chipsets, and real time clocks required for the Internet of Things (IoT), wearables, and low power portable applications.

The launch of the ABMxW and ABSxW series results in the industry’s most comprehensive family of crystals, addressing the leap to lower power. Oscillators within next generation energy saving MCUs and chipsets are failing to drive traditional crystals with higher CL and ESR. Reducing the load capacitance to a new industry level of 4pF for MHz crystals and 3pF for tuning fork crystals, while, simultaneously providing guaranteed low ESR enables operation with design margin for many chipsets starved of gain and reduced transconductance (gm). These optimized crystals ensure the crystal oscillator design retains enough margin to operate over temperature and across all process and voltage corners.

For detailed explanation of gain margin, gm, and gm_critical interdependence, review: IoT, Wearables, and Low Power: Performance Optimized Quartz Crystals

“gm (amplifier transconductance) is a critical parameter that determines your oscillator loop’s design margin,” says Syed Raza. “To minimize total power consumption, techniques employed in the latest SoC/µC/µP/RFIC/FPGA’s reduce the value of gm within the oscillator loop. To maintain the original design margin as gm drops, crystals must meet a lower gm_critical metric. Abracon’s performance optimized IoT crystals achieve exactly that, by simultaneously reducing plating load, ESR, and electrode capacitance of these devices. After all, lower power consumption should not be achieved at the expense of long term reliability or design risk.”

“The IoT, wearables, and portable markets demand the power savings achieved with next generation ICs. Those ICs directly benefit from this industry leading series of low CL crystals,” commented Juan Conchas, Director of Marketing for Abracon.

The ABMxW and ABSxW series are offered in a variety of package, stability and tolerance options down to +/-10ppm. A comprehensive offering overall operating temperatures up to -40℃ to 125℃ makes these crystals suitable for both consumer and industrial designs.

View their respective datasheets here: ABM8W, ABM10W, ABM11W, ABM12W, ABS07W and ABS06W

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IoT Quartz Crystals Product Availability

About Abracon, LLC
Founded in 1992, and headquartered in Spicewood, Texas, Abracon is a leading global manufacturer of passive and electromechanical timing, synchronization, power, connectivity and RF solutions. Abracon offers a wide selection of quartz timing crystals and oscillators, MEMS oscillators, real time clocks (RTC), Bluetooth modules, ceramic resonators, SAW filters and resonators, power and RF inductors, transformers, circuit protection components and RF antennas and wireless charging coils. The company is ISO9001-2008 certified with design & application engineering resources in Texas and sales offices in Texas, California, China, Taiwan, Singapore, Scotland, Israel, Hungary, UK, and Germany. Abracon’s products are offered through its global distribution network. For more information about Abracon, visit www.abracon.com.

Choose the right quartz crystal for your energy saving MCU with THIS simple test

Next generation MCUs and RF chipsets, commonly used in IoT, wearable, and battery powered applications, have presented a problem frequently ignored by many designers across all industries. Lower power consumption requires next generation crystals to optimize for a weaker gain and drive from the Pierce analyzer. The ability to sustain oscillation for a given quartz crystal oscillator design depends heavily on the crystal’s motional parameters, board parasitics, and oscillator circuit characteristics. Yet, as MCUs are upgraded to lower power models, their crystal counterparts have stayed the same. The Pierce oscillator circuit, a closed loop system most commonly integrated into low power ICs, sustains oscillation at an operating point, depending on the crystal plating capacitance (CL), crystal equivalent series resistance (ESR), and oscillator amplifier’s gain and phase response associated with the oscillator’s transconductance (gm). But, how do you know if your crystal’s parameters match your system?

Abracon’s Pierce analyzer system (PAS) was designed by our engineers to help you make the right choice for your industry leading designs. The PAS test validates quartz crystal performance in-circuit and simultaneously measures the crystal, crystal oscillator, and printed circuit board parasitics. Testing in-system accounts for all variables and enables ideal matching of crystal parameters to the board and oscillator in the MCU or RF chipset. This is especially critical for applications using next generation, energy saving technologies requiring optimal gm factors.

Lower CL and lower ESR increase operating gain margin of the loop, ensuring sustained oscillations across all variables including variation in bias, loading, temperature, and over time. Gm_critical is the critical transconductance value that a crystal must achieve in order to remain in the safe zone of loop operation. Crystals that do not meet gm_critical are not well matched to the Pierce oscillator and may cause long term reliability issues associated with startup. Since lower power consumption decreases gm and gm_crictical for a given Pierce oscillator, energy saving designs deployed in IoT and wearables applications are the most at risk of failure. Conducting a PAS test reduces risk and improves the reliability of your system.

“Semiconductor technology strives to wring all the power consumption out of the latest generation of MCUs and RF chipsets,” commented Syed Raza, VP of Engineering with Abracon “the on-chip Pierce oscillator is starved of much needed gain negatively impacting the gm_critical metric. The PAS test is the surest way to diagnose preventable problems.”

“As The Heartbeat of the IoT™, we strive to provide customers with as many tools and services as possible that will take their designs to the next low power plateau. The PAS test service enables validation of a critical subsystem in the design given that nothing will operate if the oscillator fails to run.” commented Juan Conchas, Director of Marketing with Abracon.

The service provides a comprehensive report outlining the functional parameters of the oscillator circuit and recommends changes when necessary. This service is conducted by Abracon and can be ordered through any franchised distributor, with multiple turn-around times from 2-weeks to 4-weeks.

Learn more about the Pierce Oscillator here.
Find more information on the PAS test, here.

Check inventory for the PAS here: PAS-BC1WK/ PAS-BC2WK/ PAS-BC3WK

About Abracon, LLC
Founded in 1992, and headquartered in Spicewood, Texas, Abracon is a leading global manufacturer of passive and electromechanical timing, synchronization, power, connectivity and RF solutions. Abracon offers a wide selection of quartz timing crystals and oscillators, MEMS oscillators, real time clocks (RTC), Bluetooth modules, ceramic resonators, SAW filters and resonators, power and RF inductors, transformers, circuit protection components and RF antennas and wireless charging coils. The company is ISO9001-2008 certified with design & application engineering resources in Texas and sales offices in Texas, California, China, Taiwan, Singapore, Scotland, Israel, Hungary, UK, and Germany. Abracon’s products are offered through its global distribution network. For more information about Abracon, visit www.abracon.com.

Abracon and TTI Inc Announce Asia Partnership

Austin, TX – Abracon, LLC (Abracon), a leading global manufacturer of passive & electromechanical timing, synchronization, power, connectivity and RF solutions, announces Asia partnership with TTI, Inc., the leading authorized distributor of interconnect, passive, electromechanical and discrete components. The Asia partnership is an extension of TTI and Abracon’s existing global distribution agreement which was announced by both companies in April 2017.

Michael Calabria, Abracon’s CEO said, “With mutual focus on IP&E and discrete components, the two companies are leaders in the industry and a natural fit. As many users of electronics components rely on the supply chain and go-to-market benefits provided by distributors, Abracon is excited to partner with TTI to support its highly valued customers.”

Anthony Chan, President of TTI Asia Pacific, commented on the addition of Abracon to TTI Asia’s specialized line card, “I am pleased to welcome Abracon to be a TTI business partner in Asia. Abracon offers a wide selection of latest technologies in frequency control, timing and synchronization. I am confident that our partnership in Asia will create additional value to our customers.”

About TTI
TTI, Inc. a Berkshire Hathaway company, is an authorized, specialty distributor of interconnect, passive and electromechanical (IP&E) components and the distributor of choice for industrial and consumer electronics manufacturers worldwide. Broader and deeper inventory, leading-edge products and custom supply chain solutions have established TTI as the leading specialist in electronic component distribution. Globally, the company maintains 1.2 million cubic feet of dedicated warehouse space containing over 850,000 component part numbers. Along with its subsidiaries, Mouser Electronics and Sager Electronics, TTI employs more than 4,700 employees and is represented in over 100 locations throughout North America, Europe and Asia. For more information about TTI, visit www.ttiinc.com.

About Abracon, LLC
Founded in 1992, and headquartered in Spicewood, Texas, Abracon is a leading global manufacturer of passive and electromechanical timing, synchronization, power, connectivity and RF solutions. Abracon offers a wide selection of quartz timing crystals and oscillators, MEMS oscillators, real time clocks (RTC), Bluetooth modules, ceramic resonators, SAW filters and resonators, power and RF inductors, transformers, circuit protection components and RF antennas and wireless charging coils. The company is ISO9001-2008 certified with design & application engineering resources in Texas and sales offices in Texas, California, China, Taiwan, Singapore, Scotland, Israel, Hungary, UK, and Germany. Abracon’s products are offered through its global distribution network. For more information about Abracon, visit www.abracon.com.

Abracon announces availability of latest components solutions catalog

Abracon, LLC. (Abracon), a leading global manufacturer of frequency control, signal conditioning, clock distribution and magnetic components, announces availability of the latest version of the components solutions catalog featuring a full line of timing & synchronization, power & energy and RF connectivity. Available in both print and soft copy, the catalog is designed to help any customer quickly arrive at passive component solutions intended for a variety of functions within IoT, wearables, communications, cloud computing, industrial, automotive, instrumentation and medical monitoring.

“Abracon supports over 20,000 active SKU part numbers with thousands of new part numbers introduced each year,” says Camille Vargas, Marketing Communications and UX for Abracon. “Our customers rely on a simplified catalog that summarizes the most significant features of each product family within the major product lines and makes it easy to select between a variety of technologies.”

Updates in this version of the catalog include numerous new product families such as IoT optimized crystals, high power toroid inductors, long range RFID tags optimized for metal surfaces, 10GBase-T RJ45 jacks with integrated magnetics and wireless charging coils for 20W solutions. Additional updates include solutions guides for antenna, ultra-low jitter and precision oscillators and high frequency programmable TCXOs.

“Concise and effective product selection tools improve our customers design cycle and get them to market quicker,” comments Juan Conchas, Director of Marketing for Abracon. “The latest version of the catalog reflects Abracon’s commitment to support customers’ need for a broad line of technology solutions that addresses the needs of today’s fast design cycles.”

To learn more and download a free soft copy of the PDF format catalog follow this link: Abracon Component Solution Catalog

To request a free hard copy of the catalog, submit your information including mailing address through this link: Request Hardcopy Catalog

Hard copy requests are fulfilled within 1 to 2 weeks.

About Abracon, LLC
Founded in 1992, and headquartered in Irvine, California, Abracon is a global manufacturer of frequency control, signal conditioning, clock distribution and magnetic components. Abracon offers a wide selection of Quartz Timing Crystals, Crystal and MEMS Oscillators, Real Time Clocks, Antennas, Bluetooth Modules, Ceramic Resonators, SAW Filters and Resonators, Inductors, Transformers, Circuit Protection Components and Wireless RF Antennas. The company is ISO9001-2008 certified with design & Application Engineering resources in California & Illinois; and Sales offices in Texas, California, China, Taiwan, Singapore, Scotland, and Germany. Abracon’s products are offered through its Global Distribution Network.

Abracon announces in-stock availability of the ATCA-XX line of high power toroid inductors

Austin, TX – Abracon Holdings, LLC announces the ATCA-XX product line, a broad offering of high power toroid inductors for use in industrial power supplies, LED ballast and heavy duty appliance applications. By containing the majority of magnetic flux within the toroid, these inductors present inherent electromagnetic and RF interference immunity. Offered with vertical or horizontal orientations, they can be placed orthogonally to minimize crosstalk when multiple devices are used.

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High Power Toroidal Inductor – ATCA Series Product Image

 

Operating temperature of -40C to 105C makes them ideal for high power and industrial applications. Designed for through-hole assembly, the product family offers standard values ranging from 20uH to 1800uH and current ratings up to 10A.

“Due to its simplicity and RFI immunity, the toroid remains a work horse inductor in high power switch mode applications,” says Juan Conchas, Director of Marketing for Abracon. “The combination of wide operating temperature and high current rating makes this broad line of toroids ideal for lighting, white goods, solar inverters, home and industrial appliances, electric motor and other industrial applications.”

These inductors are in stock for off-the-shelf commonly requested options or with short 6 to 8 week lead time for less common and custom configurations.

About Abracon Holdings, LLC.

Founded in 1992, and headquartered in Irvine, California, Abracon is a global manufacturer of frequency control, signal conditioning, clock distribution and magnetic components. Abracon offers a wide selection of Quartz Timing Crystals, Crystal and MEMS Oscillators, Real Time Clocks, Antennas, Bluetooth Modules, Ceramic Resonators, SAW Filters and Resonators, Inductors, Transformers, Circuit Protection Components and Wireless RF Antennas. The company is ISO9001-2008 certified with design & Application Engineering resources in California & Illinois; and Sales offices in Texas, California, China, Taiwan, Singapore, Scotland, and Germany. Abracon’s products are offered through its Global Distribution Network.