Compromise Impedance Match Design for Pogo Pins With Different Single-Ended and Differential Signal-Ground Patterns

A new concept of compromise impedance match design is proposed for pogo pins with various signal-ground patterns. To begin with, the methodologies of equivalent circuit modeling for single-ended and differential pogo pins are described. A de-embedding technique is proposed to eliminate the effect of a specialized test fixture for the characterization of the pogo pins. Good agreement is found from the comparison between measured and simulated results, which validates the modeling and simulation methodologies. Then, the reflection of pogo pins with various signal-ground patterns is investigated and the optimal pin radius to pitch ratio is found to be 0.20-0.21, thereby achieving a return loss better than 15 dB for all these patterns in both single-ended and differential configurations from dc to 10 GHz. In addition, the effects of pin length are considered and a general design chart is constructed for determining the pogo pin geometry and the applicable impedance range to meet the specification on the return loss. Several compromise impedance design applications demonstrating the proposed methods are given.