New microwave applications for thick-film thermistors

Two new microwave applications for temperature-sensitive thick-film materials are described. The first is a po power-screening termination, which is based on a linear negative temperature coefficient (NTC) thick-film thermistor used in combination with a linear positive temperature coefficient (PTC) material to convert RF power to DC voltage. The device can be used with a coupler to moniter power and compensate for temperature re variations. The passive device! described here is linear and represents an inexpensive replacement for currently used active devices. Processing and properties of the screen-printed , specially for formulated linear NTC and PTC thermistor materials are presented. The second application involves the use of thick-film thermistor materials to fabricate a temperature attenuator: In this design, highly nonlinear NTC materials are combined with PTC materials in T and pi configurations to maintain signal levels at constant impedance in microwave circuits. Device needs and how they may be met with thick film materials and processing are discussed.