SmartSpice RF

Frequency and Time Domain RF Circuit Simulator

SmartSpice RF™ employs a combination of time-domain shooting and frequency-domain harmonic balance methods to provide accurate simulation of GHz range RF integrated circuits. It accurately and efficiently simulates harmonic distortion, intermodulation products, gains, noise, oscillator’s phase noise in non-linear circuits using SPICE and Spectre netlists.


RF simulators address issues that are not practical or not possible with general-purpose simulators by exploiting certain characteristics of RF circuits, the most important being the relative sparsity in the spectrum of RF signals. However, these signals have different characteristics, so require different simulation techniques to produce results efficiently. While RF simulation overcomes bottlenecks associated with general-purpose simulators, it presents new challenges:

  • Difficulty to apply RF simulation to larger circuits that are not exclusively RF
  • A large number of very specialized analyses are required, which makes it difficult for designers to learn effectively and use necessary analyses

SmartSpice RF performs the large-signal analysis of RF circuits to find their time-varying operation point, and a number of subsequent small-signal analysis to define circuit response at the specified frequency. SmartSpice RF steady-state analysis employs a combination of frequency-domain harmonic balance (HB) and time-domain shooting methods to provide fast and accurate simulation of the modern radio frequency integrated circuits (RFIC). SmartSpice RF can simulate forced and autonomous periodic and quasi-periodic systems, such as amplifiers, filters, detectors, multipliers, mixers, oscillators and switch capacitor circuits. SmartSpice RF envelope analysis and digitally modulated sources library allow RF circuit designers to simulate RF circuits used in communication systems effectively.


  • Supports periodic steady-state analysis of single-tone excitation using frequency domain (Harmonic Balance) and time domain (Shooting) methods
  • Quasi-periodic steady-state (Spectral) analysis for multi-tone excitation
  • Steady-state AC (HAC, SPAC) small-signal analysis
  • Steady-state transfer functions (HTF, SPTF) for conversion efficiency, image and sideband rejection, LO feed-through and power supply rejection
  • Steady-state NET (HNET, SPNET) to compute S-parameters of two-port circuits exhibiting frequency translation with scattering (S), impedance (Z), admittance (Y), and hybrid (H) parameters, stability factors, different gains, stability circles, etc.
  • Steady-state noise (HNOISE, SPNOISE) for output noise spectrum of amplifiers, mixers, and oscillator phase noise
  • Direct periodic steady-state oscillator analysis by Harmonic Balance (HOSCIL) with phase noise extraction
  • Periodic stability analysis (PSTB) to evaluate the local stability of a time-varying feedback circuits
  • Circuit envelope simulation enables spectral re-growth, I/Q parameters, ACPR, NPR, EVM, BER simulations of amplifiers/mixers and characterization of the transmission line quality of communications systems using time-swept harmonic balance method
  • Smith charts, eye diagrams, spectral plots, histograms, signal-to-noise calculations, gain and stability circles, constellation diagrams, etc.
  • Circuit and parameter optimizer for gain, matching networks, IP3, and power dissipation for process migration


Low Noise Amplifier Design (LNA)


  • SmartSpice RF harmonic balance simulator provides frequency-domain, steady-state, large-signal analysis of non-linear circuits driven with multi-tone sources
  • Time-domain shooting method engine simulates periodic steady-state of highly nonlinear circuits
  • Optimal convergence with a complete set of interactive control parameters – spectral Newton, continuation, and GMRES solvers
  • Integrated with Gateway schematic editor for schematic entry, simulation control interface, and testbench design
  • May be integrated with popular analog/mixed-signal/RF design flows
  • Integral part of Silvaco’s complete, PDK supported, mixed-signal/RF design flow
  • Silvaco‘s secure encryption maximizes customer and third-party intellectual property protection



  • Amplifier, mixer, multiplier, oscillator, VCO, AGC, PLL, Mux, Demux, clock, and CDR designs
  • Wireless standards: GMSK, MPSK, MQAM, MFSK, EDGE, OFDM, WCDMA
Power amplifier ACPR simulation
PI/4-DQPSK trajectory diagram


Technical Specifications

  • Inputs: Gateway netlist, Spice netlist, S-parameters
  • Outputs: rawfiles, Analysis results , Measurement data
  • RF Measurement Capabilities
  • 1dB compression points
  • Nth order intercept points
  • Nth order intermodulation products
  • Mixer conversion gain
  • Two-port noise parameters
  • SSB and DSB noise figure
  • Output noise power spectral density
  • Minimum noise figure
  • Phase noise
  • Gamma opt
  • Input and output stability circles
  • Gain circles
  • Impedance/admittance locus vs. frequency
  • Large-signal S-parameters and K-factor
  • Total harmonic distortion
  • Power added efficiency
  • S-parameters