RF Design Blogs

The 7.1 release of MMSIM is scheduled for mid-January. There are many exciting RF enhancements that will be useful for RF designers.

1. Three new RF analyses using the harmonic balance engine, have been introduced to make the Spectre RF easier to use:  HB, HBAC, and HBnoise.  

• HB analysis (hb) provides the periodic steady-state response for typical RF circuits such as LNAs and Mixers. It supports one or more fundamental frequencies (tones).  HB analysis combines the Harmonic Balance PSS/QPSS analyses into one form.   In addition, the Options form for HB is greatly simplified.    
• HBAC (hbac) analysis computes transfer functions for circuits.    HBAC analysis combines the PAC/QPAC analyses into one form.
• HBNoise is similar to the conventional noise analysis, except that it includes frequency conversion effects.  HBNoise analysis combines the PXF/QPXF and Pnoise/QPNoise analyses into one form.

There are a few analyses that are not yet supported in hb (for example, stb and psp analyses).    For these analyses, we still have the previous HB PSS/QPSS (and associated small signal) analyses.  

2. Many improvements have been made for "out of the box" convergence for hb analysis. For example:

• Backtracking is improved and turned on by default.
• Improved "oscic=lin" for oscillator analysis.
• Improved tolerance settings.  
• HB for readpss/writepss, readqpss/writeqpss now supported.
• Consistent errpreset for tstab and one-extra period tran.
• Monte Carlo works well with HB and success rate is high.
• A new homotopy method (hbhomotopy) for harmonic balance has been added.
• We have provided updated guidelines to improve harmonic balance convergence for both driven and autonomous circuits.  Please see sourcelink.cadence.com solution  11514284: SpectreRF Harmonic Balance engine convergence tips for driven and autonomous circuits.

3. SpectreRF now supports multi-rate harmonic balance.  

In MMSIM 7.1., you can now partition typical RF circuits into different building blocks. Using the Multi-Rate Harmonic Balance method, you can have different harmonics set for different parts of a circuit. This new technology can make RF simulation more efficient.  Testing is showing a 2X speedup compared to previous simulations.

4.  New RF measurement library.  

You will be able to create and store your own measurements or use the basic measurement cells provided
in the new RF measurement library.  (Measurements include those for typical RF blocks such as LNA, Mixer, VCO, PA and Divider. )

5. SpectreRF now supports multi-point probing in Pnoise analysis.


6.  Transmission Line Decomposition Library.  

The rfTlineLib has been introduced in MMSIM 7.1. This library contains 7 embedded passives and transmission line components like Bend, Tee, Cross junctions, etc. In this flow, you can specify the geometry and process information for
special tline components. These components will be transformed into RLCG sub-circuits for Spectre netlisting. The library will be expanded in future releases.  

7. Semi-autonomous capability has been added for harmonic balance.

This new capability has shown good results in perturbed oscillator simulations (where you have noise say from a power supply or substrate perturbing the oscillator) and also for oscillator/mixer co-simulations.

8. The Noise Aware PLL Simulation Flow has been enhanced.    

In one of the early MMSIM7.1 ISRs, we will introduce the Sigma-Delta Library. Includes PFD/CP flicker noise and loading effects in simulation.

For more information, design tips, and troubleshooting techniques, please visit http://sourcelink.cadence.com .