As devices continue to shrink in size, so does the need to miniaturize electronic components

By Gina Roos, Editor-in-Chief

As devices
continue to shrink in size, so does the need to miniaturize electronic
components. In recent months, frequency control manufacturers have focused on
the miniaturization of both quartz crystals and oscillators. Improving jitter
performance and stability along with helping optimize power consumption are
also on the to-do list as the industry moves to higher-speed communications.

One example is
Micro Crystal AG’s 32.768-kHz quartz crystal that is housed in a footprint that
measures 1.6 × 1.0 mm with a maximum thickness of 0.35 mm. The new tiny
geometry enhances the circuitry in applications in which bending radii are
critical and complements the new bendable thin-film batteries from Renata,
said the company. Applications include smart cards, e-textile, wearables
(including activity bands), embedded modules, and health care. Both the
low-frequency CM9V-T1A crystals (1.6 × 1.0 × 0.3 mm) and CM8V-T1A (1.6 × 1.0 × 0.3 mm) are available in volume
production.

For higher-frequency
applications, IQD Frequency Products Ltd. has launched a range of quartz
crystals that can operate in the fundamental mode up to 200 MHz and are housed
in a hermetically sealed 2.5 × 2.0 × 0.6-mm (IQXC-152) and 2.0 × 1.6 × 0. 5-mm
(IQXC-153) ceramic 4-pad package.

In addition, the
quartz crystals offer improved performance. Two of the pads in the package are
grounded to the metal lid to improve electromagnetic performance (EMI). At 70
MHz to 200 MHz, the frequency tolerance can be as low as ±30 ppm. Stability is
reported at ±30 ppm over the full industrial operating temperature range of –40°C
to 85°C with the capacitance load ranging from 8 pF to 30 pF.

“The IQXC-152
& IQXC-153 enables design engineers to use higher frequencies in the
fundamental mode, which eliminates the need to use a PLL or a tank circuit
picking up the third, fifth or seventh harmonics,” said IQD. “A higher starting
frequency can also be used when looking to generate, for example, 2.4 GHz,
which cuts down on the jitter/phase noise in the circuit.” Packaging options
are tape-and-reel or cut-tape.

In the oscillator
space, the AX7 ClearClock series of oscillators from Abracon LLC targets
frequencies up to 2.1 GHz, is optimized to save power in end systems, and
offers a typical 119 fs of RMS phase jitter. The series is well-suited for low
jitter clocking needed for high serial data rates up to 56 Gbits/s and higher.

Despite reaching low
RMS phase jitter of 110 fs to 125 fs (typical, depending on output frequency),
ClearClock is optimized for low power consumption and can be used in
high-performance computing and cloud computing applications that call for
higher data rate transmission and lower power consumption.

Abracon said that previous generations of low-jitter
oscillators with less performance consumed as much as 75% higher power compared
to ClearClock under equivalent operating conditions.

The
AX7 series offers a factory configurable frequency range from 50 MHz to 2.1
GHz. Other features include OE functionality; VDD operation of 1.8 V, 2.5 V, or
3.3 V; and LVPECL and LVDS differential output logic options.

Packaged
in a standard 5 × 7-mm
footprint, the ClearClock AX7 series operates over a temperature range of –40°C to 85°C with all-inclusive
frequency stability of either ±50 ppm or ±100 ppm. Abracon’s distributors stock
the most common frequencies and output logic types.

Abracon’s AX7 ClearClock series of oscillators. (Image: Abracon)

Also
touting excellent RMS phase jitter and phase noise performance, Ecliptek
LLC offers a multi-voltage quartz crystal oscillator in a compact footprint,
measuring 2.5 × 3.2 mm (with four pads). The device offers tight stabilities
down to ±20 ppm and an extended operating temperature range of –40°C to 85°C.

The EB19E2
provides a continuous supply voltage range from 1.62 V to 3.63 V and a
frequency range from 1 MHz to 50 MHz. “The variable supply voltage feature
allows customers to use the EB19E2 Series across multiple platforms with a
range of supply voltages,” said Ecliptek. Target applications include medical
equipment, Gigabit Ethernet, Fiber Channel, routers, servers, and hubs.

In the high-performance end of the market,
frequency control manufacturers are also making performance improvements to
their lineup of oven-controlled crystal oscillators (OCXOs), voltage-controlled
crystal oscillators (VCXOs), and temperature-compensated crystal oscillators
(TCXOs) for extreme environmental conditions.

Offering a high temperature range and high
stability, the XO517X series of OCXOs from MtronPTI is designed as a timing
reference for extreme environment applications. The XO517X series offers
temperature stability of less than ±1.0 ppb over an extended operating
temperature range of –40°C to 90°C. Available frequency range is 10 MHz
and 40 MHz. Customers should contact the company for other frequencies.
Applications include ground-based SATCOM, troposcatter communications, extended
temperature military/aerospace/avionics applications, downhole seismic
equipment, and high-temperature industrial controls.

Nihon Dempa Kogyo (NDK) is combining the best
of two worlds: packing performance in smaller packaging for higher-performance TCXOs.
The company claims the smallest low-g sensitivity TCXO housed in either a 2.0
× 1.6 × 0.7-mm footprint or a high-precision version supporting Stratum 3 and
ITU-T TR-G8262 applications in a 3.2 × 2.5 × 1.1-mm package.

NDK said that the
vibration sensitivity (0.1 ppb/g) of the TCXOs are 10 times better than
conventional TCXOs. This makes them suited for applications such as those in
outdoor environments, cooling fans, drones, and any application that uses
communication devices and other sources that could affect oscillators.

XOs/VCXOs
target 56G SerDes
Timing
device manufacturers are also prepping for higher-speed serial communications
applications. Silicon Labs offers a portfolio of high-performance clocks and
oscillators aimed at the 56G PAM-4 SerDes and emerging 112G serial
applications. “56G designs rely on four-level pulse-amplitude
modulation (PAM-4) signaling for serial data transmission to increase the bit
rate per channel while keeping the bandwidth constant,” said Silicon Labs.

To meet these
requirements, Silicon Labs’ product portfolio now includes
the Si539x clocks that deliver frequency flexibility and low jitter and the
Si56X Ultra Series of crystal oscillators (XOs) and VCXOs.

The Si5391 any-frequency clock generator claims the
industry’s lowest jitter. The company also touts that it is the only clock
generator that can provide all clock frequencies needed in 200/400/600G designs
from a single IC while delivering sub-100-fs RMS phase jitter for 56G SerDes
reference clocks. The device features up to 12 differential outputs and is
available in frequency A/B/C/D grade options.

“A Precision
Calibration P-grade option optimizes RMS phase jitter performance with a 69-fs
(typical) specification for the primary frequencies needed in 56G SerDes
designs,” said Silicon Labs. “The Si5391 is a true sub-100-fs ‘clock-tree-on-a-chip’
solution designed to synthesize all output frequencies from the same IC while
meeting 56G PAM-4 reference clock jitter requirements with margin.”

The Si539x jitter
attenuators also claim industry-leading jitter performance and frequency
flexibility. These ultra-low any-frequency jitter clocks generate any
combination of output frequencies from any input frequency while delivering 90-fs
RMS phase jitter, according to the company.

The Si5395/4/2
P-grade devices offer best-in-class jitter (69-fs RMS typical phase jitter) for
56G/112G SerDes clocking applications, said Silicon Labs.

The Si5391 and
Si539x families are supported by Silicon Labs’ ClockBuilder Pro (CBPro)
software for easier device configuration and customization. The company said that
customers can customize a clock solution using the CBPro and get samples in as
little as two weeks.

The Si56x Ultra Series VCXO/XO family is
well-suited for next-generation high-performance timing applications that
require ultra-low-jitter oscillators. The company said that the Si56x VCXO/XOs
are customizable to any frequency up to 3 GHz, supporting twice the operating
frequency range of previous VCXO products with half the jitter.

The Si56x
oscillators are available with single, dual, quad, and I2C-programmable options in 5 ×
7-mm and 3.2 × 5-mm packages. This enables the devices to be drop-in-compatible
with traditional XOs, VCXOs, and VCSOs. Typical phase jitter is as low as 90
fs.

Purpose-built for 56G designs, Silicon Labs also
offers the Si54x Ultra Series XO family that targets applications that require
tighter stability and guaranteed long-term reliability, such as optical
transport networking (OTN), broadband equipment, data centers, and industrial
systems.

“Using an Si54x
XO as a low-jitter reference clock maximizes signal-to-noise ratio (SNR)
headroom, minimizes bit errors, and enhances signal integrity,” said Silicon
Labs. Typical phase jitter is as low as 80 fs.

1018_Roundup_Silicon-Labs

Silicon Labs’ high-performance clocks and oscillators aimed at 56G PAM-4 SerDes and emerging 112G serial applications. (Image: Silicon Labs)

MEMS oscillators make inroads into high-reliability applications
Touting
advantages in stability, reliability, robustness, and low phase noise and
jitter, microelectromechanical systems (MEMS) oscillators are making inroads
into applications such as automotive and telecom that call for improved timing
performance and high-reliability parts that can withstand extreme environmental
conditions.

One example is
the DSA family from Microchip Technology Inc., which debuted earlier this year
as the industry’s first automotive-grade multiple-output MEMS oscillator. “Technological advancements
and the increased adoption of complex electronics systems in modern vehicles
require superior timing performance and reliability,” said Microchip. “Timing
precision, accuracy, and tolerance to harsh environments are essential to
ensuring precise operation in today’s highly advanced automotive systems.”

The DSA family consists of the
DSA1001, DSA11x1, DSA11x5 and DSA2311, which offer high tolerance to mechanical
shock in harsh environments over a frequency range of 2.3 MHz to 170 MHz. The
devices are Automotive Electronics Council Q100 (AEC-Q100)-qualified with ±20
ppm stability over temperatures ranging from –40°C to 125°C.

Some application examples that
require tight frequency stability over a wide temperature range include
advanced driver assistance systems (ADAS), light detection and ranging (LiDAR),
in-vehicle Ethernet, and autonomous driving.

The DSA family claims to provide
20-times-better reliability, 500-times-better tolerance to shock, and five-times-better
vibration resistance than traditional quartz-based crystal devices.

1018_Roundup_Microchip

Microchip Technology’s DSA family of MEMS oscillators are AEC-Q100-qualified with ±20-ppm stability over a temperature range of –40°C to 125°C. (Image: Microchip Technology)

As a multiple-out MEMS oscillator,
the device can replace multiple crystals and oscillators. Microchip said that the
DSA2311, for example, can replace two crystals or oscillators on a board. It’s
housed in a small 2.5 × 2.0-mm package, delivering more space savings. Target
applications include infotainment systems and cameras.

Microchip offers designers a
ClockWorks online configurator tool to help them select the right oscillator
based on their specific requirements for frequency, package size, and
temperature range. Designers can also order free samples via the tool.

Another MEMS timing manufacturer,
SiTime Corp., offers a family of MEMS-based timing and synchronization
solutions for 5G applications. “In a dense 5G network that transmits
at higher speeds, radio-to-radio time accuracy must be within 65 nanoseconds —
20 times better than 4G,” said SiTime. At the same time, timing solutions need
to withstand tough environmental conditions such as shock, vibration, rapid temperature
changes, and extreme temperatures, added the company.

SiTime said that its
MEMS-based timing solutions can meet these requirements “while offering
20-times-better reliability and one-fifth the power.”

SiTimes’ Elite
family of Super-TCXOs offer tight stability (±0.1 ppm to ±2.5 ppm) over a frequency range
of 1 MHz to 220 MHz. These high-precision oscillators can replace legacy
quartz-based OCXOs in 5G and IEEE 1588 synchronization applications, reducing
size and power, according to the company.

Other key specs
include 30-times-better dynamic stability, I2C digital frequency tuning, and
on-chip power supply noise filtering. The operating temperature range is –40°C to 105°C.