Skip to main content

Operating Modes

The operating mode tells the analyzer whether your chain is for transmit or receive (or both), which fundamentally changes how the RF performance is evaluated:

  • TX mode: Analyzes upconversion (baseband/IF → RF).
  • RX mode: Analyzes downconversion (RF → baseband/IF).

This affects which metrics are computed, which warnings are generated, which display sections appear, and how the main signal path moves through a mixer. Set it in the System Spec panel or using the mode selector in the header.

If you change operating mode after you have already built part of a chain, SigChain asks for confirmation first because some existing connections may no longer fit the new direction.

The stage table shows the same core columns for all modes. The System Summary row and Output Metrics section are mode-aware — see Analysis Metrics for the full breakdown.

TX mode​

Use for transmit-only chains such as DAC → mixer → PA → antenna/output.

What's computed and shown:

  • Total gain, output power
  • Cascaded OIP3, OIP2, OP1dB
  • NSD Out, Noise Floor, SFDR
  • Output Metrics section: V_RMS, V_PP, SNR, IMD3, IMD2, harmonic estimates
  • Psat margin per PA/driver stage
  • Headroom to P1dB, Psat, and max_input for each stage

RX mode​

Use for receive-only chains such as antenna → LNA → mixer → ADC.

What's computed and shown:

  • Total gain, cascaded NF
  • Cascaded IIP3, IIP2, IP1dB
  • NSD Out, Noise Floor, SFDR
  • Output Metrics section: V_RMS, V_PP, SNR, IMD3, IMD2, harmonic estimates
  • Stage-level metrics: gain, input power, NF, IIP3/OIP3, OP1dB/IP1dB, headroom margins

Display Behavior​

All modes display the same stage table with columns for:

  • Gain and cascaded gain
  • Input/output power
  • Noise figure (per stage and cascaded)
  • IIP3, OIP3 (per stage and cascaded)
  • OP1dB (per stage and cascaded)
  • Headroom margins (P1dB, Psat, max_input)

The Output Metrics section (V_RMS, V_PP, NSD, Noise Floor, SNR, IMD, harmonics, SFDR) appears for all modes.