CASE STUDIES:
Pressure Sensor Electronics Redesign for Cost Reduction

Situation: Our client had developed a line of low-cost pressure sensors. Unfortunately, the cost of the electronics exceeded the required cost target, making the product's pricing prohibitive. The firm asked us to redesign the electronics to reduce the sensors' cost and bring it in line with market benchmarks.

The electronics included a single PCB assembly, which contained an analog front end with an interface to the capacitive pressure transducer; a micro-controller; D/A; temperature sensor (for compensation); and ancillary power and conditioning circuitry.

Solution: We determined that redesigning the circuitry and using an alternative approach for many of the product's functional elements could enable this client to meet their cost goals. We proposed an electronics redesign that would reduce costs while also sustaining the sensors' current adequate performance. To those ends, our project team redesigned the following circuit elements:

• a front end "super-buffer" with hysteretic feedback, this is a 1/C-to-frequency circuit
• ratiometric circuitry was used to reduce dependence on voltage references
• a low-cost micro-controller
• a PWM used for D/A functionality

Results: Thanks to this redesign effort, our client's products demonstrated improved performance and achieved a 65% reduction in unit cost. These results exceeded the client's original goal, inspiring a long-time partnership between the client and Venture Technologies.