Optically frequency modulated 6 GHz MMIC oscillator

Modelling and design of optically controlled MMIC oscillators

“…Although this is adequate for the switching/phase shifting function concerned, for more general application, complete large-signal models for the MESFET under the full range of bias and illumination conditions are required. For this paper we have developed large-signal optical models for a MESFET and a varactor diode used on an optically controlled MMIC VCO [1]. These models have been verified not only through comparison with individual test devices, similar to what has been achieved before, but also by simulating the performance of the complete VCO circuit under different bias and illumination conditions.…”

“…A self-bias arrangment is used with the required gate-source voltage of OV obtained by providing a DC return on both source and gate. Previously, a series resistance was used for the non-zero self-bias in [1]. The design in Fig.…”

“…Varying the applied bias can give electrical tuning although it was found that reducing the bias below l.5V stopped the oscillation, as the MSM capacitance became too large. The MMIC oscillator was characterised using the same measurement technique outlined in - [1].…”

“…In such systems there is often a high component count and the use of MMIC technology leads to significant cost savings. In recent years a number of research groups have investigated incorporating optoelectronic functions on MMICs; for example, optical tuning [1], injection locking [2] and switching [3] have been achieved.…”

“…In previous work [1] we reported optical tuning of a MMIC MESFET oscillator; through modulation of the optical control signal we generated FM on the microwave output. In this paper we investigate injection locking as a means of not only stabilising a MMIC oscillator but again to generate FM.…”