Today, we are releasing an updated information video about TINACloud, the cloud-based, multi-language version of the popular circuit simulation software TINA DesignSuite.
This video showcases how you can access an industry-standard circuit simulation environment directly from your web browser—no installation required. From analog and digital design to advanced AI-assisted code generation and symbolic analysis, TINACloud provides a seamless workflow for engineers, educators, and students. Discover why industry leaders like Infineon Technologies trust TINACloud as the engine for their own online prototyping tools.
In our latest video, we demonstrate the application of the Harmonic Balance (HB) method in TINACloud by analyzing a frequency doubler circuit that uses a GaAs FET transistor and microstrip stub filters to optimize circuit operation.
In TINA v16, TINACloud and later versions, you can analyze nonlinear RF and Microwave circuits using the Harmonic Balance analysis method.
The advantage of this approach is that it does not require detailed time-domain simulation, which can be prohibitive for GHz-range signals.
Instead, you simply specify the desired base harmonics, and the program calculates and displays the resulting spectrum lines.
GaAs FET Frequency Doubler circuit
Open the Frequency Doubler GasFET file from the TINAExamples\RF\HB folder.
This frequency doubler circuit generates a 4 GHz output signal, exactly two times the2 GHz input frequency, using a high frequency GaAs FET transistor.
Besides the GaAs FET transistor, the circuit contains two other parts of interest.
A short-circuited half-wavelength stub (λ/2, λ, 3λ/2, …), TL11, is connected to the gate of the FET. It exhibits resonant frequencies at 4 GHz and integer multiples, thereby suppressing the 4 GHz component and its harmonics at the gate.
In addition, a second open-circuited quarter-wavelength stub (λ/4, 3λ/4, …), TL9, is connected to the drain of the FET. It exhibits resonant frequencies at 2 GHz and its odd multiples, thereby filtering out the 2 GHz fundamental frequency component from the output signal.
GaAs FET Frequency Doubler circuit
Running the Harmonic Balance Analysis
To observe the output spectrum, navigate to the Analysis menu and select Harmonic Balance Analysis. Use the following parameters:
Base frequency: 1 GHz
Number of harmonics: 20
Output: Vout
The analysis results clearly demonstrate the circuit’s effectiveness. The dominant spectral component appears at 4 GHz (the second harmonic) with an amplitude of 199.34 mV. Meanwhile, the fundamental 2 GHz component is suppressed to a mere 8.45 mV, confirming successful frequency doubling.
Harmonic Balance Diagram
Verification: Transient and Fourier Analysis
TINACloud allows you to validate your HB results using traditional time-domain methods.
1. Transient Analysis
When you run a Transient Analysis, the waveform visually confirms the doubling effect: the output period is half that of the input. By placing cursors on the curves, the Diagram Window confirms the frequencies:
Vin: 2 GHz
Vout: 4 GHz
Transient Analysis Vin result: 2GHz
Transient Analysis Vout result: 4GHz
2. Fourier Series Analysis
For a final numeric check, we can convert the transient data into the frequency domain. Run Fourier Series Analysis with these settings:
Sampling Start time: 200 ns (to ensure the circuit has reached a steady state)
Base frequency: 1 GHz
Number of samples: 4096
The resulting Fourier amplitudes and phases show excellent agreement with the Harmonic Balance data, providing total confidence in the design.
Fourier Series Analysis diagram
Conclusion
The combination of GaAs FET technology and Microstrip Stub Filters creates a robust frequency doubler, and TINACloud’s Harmonic Balance engine provides a streamlined alternative to traditional time-domain methods. By avoiding the overhead of long time-domain simulations, you can iterate faster and refine your microwave designs with ease.
In our latest tutorial video, we demonstrate the application of the Harmonic Balance (HB) method in the online TINACloud software, where the high computational speed of the HB method provides a significant advantage.
Introduction to Harmonic Balance (HB)
In TINA v16, TINACloud and later versions, you can analyze nonlinear RF and Microwave circuits using the Harmonic Balance analysis method.
The HB Advantage: The advantage of this approach is that it does not require detailed time-domain simulation, which can be prohibitive for GHz-range signals. Instead, you simply specify the desired base harmonics, and the program calculates and displays the resulting spectrum lines.
Finding the Examples: You can follow along by opening the built-in examples. Navigate to the Examples > RF > HB folder within the TINACloud file menu.
1. Frequency Tripler Circuit
We start with a fundamental nonlinear process: frequency multiplication.
Example File:Tripler BJT.TSC (located in Examples/RF/HB).
Frequency Tripler Circuit
Circuit Overview: This frequency tripler circuit generates a 2.4 GHz output signal, exactly three times the 800 MHz input frequency, using a high-frequency bipolar transistor (MMBR941).
Executing the Simulation: To see the results, go to the Analysis menu and select Harmonic Balance Analysis. Ensure the settings are configured correctly and that Vout is designated as the Output.
The Results: The spectral output confirms a successful tripling effect:
The third harmonic (2.4 GHz) is the dominant peak, reaching an amplitude of 113.85 mV.
The fundamental component (800 MHz) is significantly lower at only 1.77 mV.
Frequency Tripler Circuit:Harmonic Balance Analysis
In TINACloud, you can also display the spectrum lines graphically by clicking the Diagram button in the Dialog window.
Frequency Tripler Circuit: Harmonic Balance Analysis, Amplitude diagram
2. AM Demodulator and Direct Frequency Specification
One of the most powerful features of TINACloud’s HB analysis is Direct Frequency Specification. This allows you to manually list the specific frequencies you wish to analyze—an invaluable feature for signals with vastly different frequency components.
Example File:AM Demodulator with PIN Diode.TSC
Circuit Overview: This circuit features a PIN diode detector designed to demodulate an Amplitude Modulated (AM) signal. An RC low-pass filter is integrated at the output to extract the original modulating information. The input consists of:
A 1 GHz carrier wave.
Two sidebands offset by 100 kHz from the carrier.
The Power of Direct Specification: If we tried to analyze this using a standard base frequency of 100 kHz, the software would have to calculate over 10,000 spectral lines to reach 1 GHz. This would be incredibly slow and unnecessary. The Solution: In the HB Analysis settings, we directly input only the three frequencies we care about. TINACloud then quickly calculates the resulting voltages, including the demodulated 100 kHz signal.
AM Demodulator with PIN Diode circuit: Harmonic Balance Analysis dialog
Transient Analysis and Fourier Analysis
While Harmonic Balance is excellent for frequency data, TINACloud allows you to verify these findings using traditional time-domain methods.
Transient Analysis: Run a standard Transient simulation from the Analysis menu to see the high-frequency AM wave and the extracted low-frequency signal.
Fourier Analysis: To perform the Fourier Series analysis, select Fourier Analysis from the Process menu of the dialog window, then click Fourier Series… Set the parameter values as shown in the Analysis dialog.
AM Demodulator with PIN Diode circuit: Transient Analysis
AM Demodulator with PIN Diode circuit: Fourier Analysis dialog settings
Comparison:
Fourier Result: 208.75 mV at 100 kHz.
Harmonic Balance Result: 202.70 mV at 100 kHz.
AM Demodulator with PIN Diode circuit: Harmonic Balance and Fourier Analysis
The calculated 208.75 mV at 100 kHz is very close to the 202.70 mV calculated using the Harmonic Balance method.
Conclusion
The Harmonic Balance analysis method offers high computational efficiency, as it avoids detailed time-domain simulations that can be prohibitive for GHz-range signals. Instead, the desired base harmonics are specified directly, and the resulting spectral lines are calculated and displayed, making the method particularly well suited for online simulation.
The growing performance of modern computers makes time-domain methods increasingly competitive with the Harmonic Balance method.
