Dropped cell phone calls could soon be history

Micrel today announced details of its RippleBlocker technology; a development that will help make those annoying dropped mobile phone calls a thing of the past. As the name suggests, Ripple Blocker technology removes noise from the power supply. Essentially, the Ripple Blocker technology is an active filter integrated in Micrel’s new low drop out (LDO) linear regulators and load switches.

This small and innovative solution can make a big difference in numerous high-volume consumer products such as cell phone and tablets, by enhancing performance and saving component count and space, both of which are always a premium in these portable devices. 
So who needs this technology? 

– Image Sensors – For higher image quality
– Transducer Circuits – For increased sensitivity
– Global Positioning Systems – Reduces signal acquisition time and increases position accuracy
– Cellular Phones – Fewer dropped calls and improved signal strength
– RF Products (Wi-Fi, Wi-Max)


To develop camera modules with image sensors capable of capturing low-level signals in low light conditions such as night time, designers have to overcome the noise generated by the DC/DC regulators. Typically, designers use discrete components to add passive filtering at the output of an LDO. For portable power applications, designers use a load switch to reduce battery drainage when the load is removed. In this case designers often select an off-the-shelve load switch, adding a discrete passive filter after the load switch.

Other applications, such as a portable GPS, cell phone or RF device, must receive and process very low-level signals. RF power supply rails need to be very clean to avoid compliance issues in both Tx and Rx, making the removal of power supply noise and ripple critical to performance. Ripple Blocker technology suppresses noise and ripple far more effectively that discrete solution. Many applications employ a DC/DC switching regulator to power other devices on the board. Filters reduce some of the switching ripple but there is always some ripple left. 

 A portable product designer that places Micrel’s new MIC94300 load switches with Ripple Blocker technology at the output the DC/DC regulator will see the virtual elimination of ripple, and dramatic reduction in switching noise and its harmonics. This is due to the exceptional Power Supply Rejection Ratio (PSRR) provided by the MIC94300 load switch.

To understand the full benefit of Micrel’s solution, one requires a quick size comparison with a discrete solution. Discrete solutions place a large inductor and ceramic capacitor after the load switch to get rid of the noise and ripple. 

The MIC94300 eliminates the inductor and dramatically reduces the size of the capacitor needed. In all, this saves about 65% of the board space used and reduces the component count, a premium in applications such as cell phones. 

What if, instead of a load switch, the circuit requires a linear regulator to power other ICs? 

In the case where an LDO is used at the output of the switching DC/DC regulator, discrete solutions require an additional LC filter to improve their PSRR at higher frequencies. Micrel’s new LDO, the MIC94310, has Ripple Blocker technology, so no need for the extra components. 

– It saves up to 56% board space.
– Improves minimum detectable signal capturing for low-light sensitive image sensors
– Provides clean system power for Image System Processors (ISP)

Tiny integrated solution enables more usable board space to implement feature-rich system solutions

Please do take a look at the full samples list via Micrel

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