BAW Resonator Technology
BAW is a micro-resonator technology that enables the integration of high-precision
and ultra-low jitter clocks directly into packages that contain other circuits. In
the LMK6C and CDC6CLVCMOS oscillators, BAW is integrated with a
co-located precision temperature sensor, a ultra-low jitter, low power output
divider, and a small power-reset-clock management system consisting of several low
noise LDOs.
Figure 1 shows the structure of the BAW resonator technology. The structure includes a
thin layer of piezoelectric film sandwiched between metal films and other layers
that confine the mechanical energy. The BAW utilizes this piezoelectric transduction
to generate a vibration.
BAW Oscillator in Motor Drive Systems
Motor drive systems are used in many industrial
and manufacturing applications. These systems require precise control of position,
torque, and speed for robust and reliable performance. Many applications such as AC
inverter and VF drives, single and multi-axis servo drives, and stepper drives rely
on EtherCAT® to transmit data to
the host processor, which requires a reliable clocking architecture to achieve the
best performance. Figure 2 shows a common clocking architecture for standard EtherCAT applications.
Benefits of the BAW
Oscillator
TI's BAW oscillators have many
benefits including the following:
- BAW oscillators are available in
standard 4-pin package sizes, including the industry's smallest 1.6mm x 1.2mm.
Figure 3 showcases BAW Oscillator layouts on the left in comparison to typical crystal
layouts for several package sizes. Crystals require up to four external
components to tune the resonant frequency and maintain active oscillation.
Active oscillators such as the CDC6C or LMK6C only require a single capacitor
for power supply filtering, which simplifies the BOM and significantly reduces
the layout area required. Additionally, parasitic capacitance from PCB traces
will not affect the frequency accuracy of an active oscillator which allows it
to be placed much farther away from the receiver compared to crystal.
- BAW technology enables high
resiliency to harsh environmental conditions, such as mechanical shock and
vibration and achieves 100× better MTBF compared to quartz based designs. As
shown in Figure 4, BAW
oscillators experience only 1 ppb/g vibration sensitivity, which is 10× better
than quartz-based designs.
- BAW oscillators maintain a
temperature stability of ±10 ppm over temperature from -40 to +105°C.
- LMK6C oscillators support a
typical RMS jitter of 200fs, resulting in optimized bit-error-rate (BER)
performance of the Ethernet PHY.
- BAW oscillators include an
integrated LDO which provides high-power supply noise immunity.