Optimal Design Of Driving Circuit For Ka-Band Ferrite Phase Shifter

Phase shifter is a device which can adjust the phase of the electromagnetic waves. It is applied in the field of guidance, navigation, telemetry, electronic warfare, radar, microwave equipment and measurement systems, medical equipment and other military and civil engineering systems. Above the S-band frequency, ferrite phase shifter is very advantageous in many ways, such as power capacity, insertion loss, reliability and durability. It has a dominant position in passive array radar. Ka-band ferrite phase shifter driven in the way of flux control is very easy to be realized, and its volume is very small. It presents very low insertion loss and high accurate differential phase shift.In this paper, a controlling and driving circuit of 4-bit for Ka-band phase shifter based on CPLD technology was fabricated. Three aspects of the driving circuit are emphasized in the following.1. Switch time optimization. Based on the composition of switch time, an optimized design of the driver circuit was carried out. The moderate switch time is 3.2μs.2. Optimization of phase shift precision in high temperature. Effect of temperature on the performance of phase shifter was investigaed. Different temperature feedback systems focusing on the phase shift accuracy was exhibited. The root mean square error is controlled within 5° at the range of 25-80℃.3. Circuit miniaturization and the optimization of PCB. The driving circuit is optimized by using a reasonable multilayer board and circuit partitioning scheme.The test results reveal that the circuit works well and it can generate excitation pulse to drive the phase shifter stably. The max phase shift is 360℃ at the range of 25-80℃, and root mean square error of phase shift is controlled within 5°. The switch time is less than 3.2μs.