Examples > Microwave Circuits > 2GHz BJT Low Noise Amplifier Print version of this topic

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2GHz BJT Low Noise Amplifier

Location: \examples\MW_Ckts\LNA_prj

Objective

This example shows a simple procedure for designing a low-noise amplifier. The specifications are: 3 V supply, 2 mA collector current, lowest noise at 2 GHz, gain > 10 dB at 2 GHz, input and output reflection coefficients better than -10 dB at 2 GHz and unconditionally stable.

Setup

1. "Curve_Tracer.dsn" simulates the collector current versus collector voltage with the base current swept as a parameter.

2. "DC_and_Sparams.dsn" shows a bias network design, and includes a simulation of the S-parameters and a calculation of the stability of the biased device.

3. "Gain_and_Stab_opt.dsn" shows the addition of an optimized stabilizing networks added to achieve unconditional stability, simulated from 0 to 3 GHz.

4. "Circles.dsn" simulates the S-parameters, noise parameters and stability parameters before the addition of input and output matching networks.

5. "Input_match.dsn" designs the input matching network to generate a source impedance that is a tradeoff between gain and noise figure.

6. "Amp_wInputMatch.dsn" shows a simulation of the amplifier with both stability networks and the input matching network added.

7. "Output_match.dsn" designs the output matching network for simultaneous conjugate match.

8. "Amp_wBothMatches.dsn" simulates the amplifier with stability networks and both matching networks added. The results are not as good as expected, so an optimization is run next.

9. "Amp_wMatchOpt.dsn" is an optimization of the input and output matching component values to achieve a better gain, input match, and output match at 2 GHz, while not degrading the noise figure.

10. "DC_OP_POINT.dsn" simulates the colelctor current versus base voltage, with the collector voltage set to 3 V.

Analysis

Figure 1: Gain and Noise Circles.