No question, the miniaturization of electronics devices and their ever-increasing functions give designers headaches. When marketing departments freeze the form factor and specifications of the end-device, designers and pc-board layout experts must deal with it, making their jobs a balancing act. Once the core ICs have been selected and placed on the board, they must design basic, but essential, circuits for impedance matching, ESD protection, line termination, and filtering.
Traditionally achieved with discretes, new integrated solutions offer significant space savings compared to standard-size components like 0402, 0201, or even 01005 surface mount packages (SMD). The right trade-off between flexibility and overall space savings is critical. Benefiting from their accrued in-depth application knowledge, semiconductor companies have developed products for many design cases that don't compromise performance or board space.
Save space
This space savings, won by integrating discrete components into a single chip, is the result of three factors. First, when integrating separate components on a die, semiconductor engineers can use a single band-gap to cover the complete die. Second, mounting a component on a pc-board leaves a gap — or pitch — between nearby packages to evacuate solder excess and avoid the “tombstoning” phenomenon or other assembly defects. Third, interconnecting discrete components on a board devours millimeters of metal lines and space-consuming vias while semiconductor engineers can interconnect the discrete components on silicon die with micrometers of metal lines. These tiny interconnections created by semiconductor process contribute to decreasing the overall space needed and drastically reduce the undesired parasitic effects of the metal lines (parasitic RLC). Designers working on EMI rejection know a low-parasitic solution is crucial to avoiding multiple design and layout iterations and matching the specified pattern.
Integrated passives cut PCB size and BOM count.
Integrating passive and active components in a single package additionally benefits the tolerance range due to semiconductor process control. Matching components processed on the same die from the same wafer is far easier than matching discrete components. For instance, when designing ESD protection on differential high-speed lines (HDMI, USB 3.0, and so on), matching the capacitance of the differential lines is far easier to achieve when using dual-line ESD protection (single package) than two single-line ESD protection devices (two separate packages from different lots). The use of integrated passive and active devices simplifies simulations and reduces the parameters involved in corner-lot analysis. By replacing discrete components with an off-the-shelf solution, designers accelerate time to market with an improved form factor and better performance.
The STMicroelectronics' BAL-SPI-01D3 is a super-small 1.4 x 2.0-mm balun for 868- and 915-MHz build on a glass substrate.
Example devices
As an example, the STMicroelectronics' ECMF02-3HSM6 is a common-mode filter that includes ESD protection. Their BAL-SPI-01D3 is an outstanding ultraminiature 1.4 x 2.0-mm balun with 50 Ω input impedance which integrates the matching network and harmonics filter and enables 50% to 80% space saving on the pc-board with perfectly matched integrated components.
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