ECS - Frequency control and Management
Frequency control devices manufactured by ECS are Surface Mount Crystals/Oscillators, VC-TXCO's and Programmable Oscillators.

Oscillator Circuit Design Considerations
Crystal controlled oscillators may be considered as consisting of an amplifier and a feedback network that selects a part of the amplifier output and returns it to the amplifier input.
ECS, Inc. International
15351 West 109th Street, Lenexa, KS 66219, USA.