CST – Computer Simulation Technology

Co-Simulation of a MMIC Low Noise Amplifier and a 3D via Hole Structure

CST DESIGN STUDIO™ has been used for a simultaneous optimization of circuit elements with the built-in circuit simulator and the inductance of a 3D via hole model with CST MICROWAVE STUDIO® (CST MWS). For more complex layouts CST MWS 3D models can be used in Agilent ADS.

This example is based on an application note of a Philips Silicon MMIC low noise amplifier. It can be used for RF front ends, wide band applications (e.g. cellular phones, cordless DECT), low noise amplifiers, satellite television tuners, high frequency oscillators. Because of it‘s low power-consumption, it is well suited for pager front-end applications.

Figure 1: Schematic of the circuit

The Low Noise Amplifier contains a BFG403W Double Poly RF-transistor. The LNA is designed for a frequency f=900MHz, VSUP~1.5V, ISUP~1mA....

Measured performance at f=900MHz: Noise Figure NF~1.8dB, gain S21 ~16dB.

Figure 2: Circuit Representation in CST DESIGN STUDIO™

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Figure 3: 3D view of the via hole model in CST MICROWAVE STUDIO®

The CST MWS simulation of the via hole needs approx. 30 seconds for an adapted (converged) mesh density on an Intel Pentium 1600 MHz processor.

Figure 4: S21 values of amplifier

S21 values of amplifier for different values of microstrip length L1 in the 3D model and capacitance of C1, inductance of coil_1 and coil_2 in the circuit.

The ability of storing data in a global cache and interpolation between results leads to a speed up of the simulation.

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