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LTspice .MEAS Statement Reference

This document contains .MEAS statement examples for various simulation types.

.MEAS results appear in the SPICE Output Log (View → SPICE Output Log, or CTRL+L)

Table of Contents

How .MEAS Statements Are Executed

.MEAS statements are evaluated in post processing, after the simulation has completed — they operate on the saved waveform dataset, not on the running simulation.

Running a .MEAS Script Without Re-Simulating

Because measurements are pure post processing, you can write .MEAS statements and execute them against an existing dataset:

  1. Make the waveform window the active window
  2. Execute menu command File > Execute .MEAS Script

This re-measures the waveform data already on disk, so there is no need to re-run the simulation to add or change a measurement. Useful for long transient runs, and for iterating on measurement expressions against a fixed dataset.

The script can be an ordinary netlist. LTspice ignores everything in the file except the .MEAS statements — component lines, other dot commands, and the title line are all skipped. So you can point Execute .MEAS Script straight at the circuit’s own .net or .cir file: edit or add .MEAS lines there, execute the script, and read the new results without touching the simulation.

The usual alternative is to place .MEAS statements on the schematic as a SPICE directive (or in the netlist alongside the other simulation commands), in which case they run automatically at the end of each simulation.

.MEAS with AC Analysis - Key Functions

Measurement Functions

Function Description
V(node) Complex voltage (magnitude and phase)
I(component) Complex current through component (magnitude and phase)
mag(V(node)) Voltage magnitude
mag(I(component)) Current magnitude
ph(V(node)) Voltage phase in degrees
ph(I(component)) Current phase in degrees
re(V(node)) Real part of complex voltage
re(I(component)) Real part of complex current
im(V(node)) Imaginary part of complex voltage
im(I(component)) Imaginary part of complex current

Measurement Operations

Operation Description
FIND ... AT freq Find value at specific frequency
WHEN condition Find frequency when condition is met
MAX Find maximum value
PARAM {expr} Calculate parameter from measured values
CROSS=1 First crossing of condition
CROSS=2 Second crossing of condition
CROSS=LAST Last crossing of condition

Best Practices:

  • Use .options meascplxfmt=polar to display results in linear magnitude and phase (default is dB and phase)
  • Use .options meascplxfmt=cartesian to display results in real and imaginary format
  • Use relative measurements (e.g., Vout_max/sqrt(2)) instead of absolute thresholds for robustness
  • Functions mag(), ph(), re(), and im() extract specific components of complex AC voltages and currents

AC Analysis .MEAS Examples

  1. Measure Amplitude at a Specific Frequency
  2. Find the Amplitude at a Specific Frequency (Linear Format)
  3. Measure Amplitude at Specific Frequency (Cartesian Format)
  4. Find DC Gain (Gain at Lowest Frequency)
  5. Find -3dB Cutoff Frequency
  6. Measure Phase at Specific Frequency
  7. Measure Phase at Specific Frequency - Default Reporting in dB
  8. Find Frequency Where Phase = -45°
  9. Calculate Slope
  10. Measure Bandwidth (Between Two Frequencies)
  11. Find Maximum Output
  12. Quality Factor (for Bandpass Filters)

Important Note: Amplitude results from .MEAS statements in AC simulations are always reported as complex numbers (magnitude and phase), even when measuring only the magnitude, phase, real, or imaginary portions of a data point. The display format can be controlled with .options meascplxfmt=polar (linear magnitude, phase in degrees) or the default dB format (dB magnitude, phase in degrees).

Measure Amplitude at a Specific Frequency

Complete netlist:

* RC Low-Pass Filter - Measure Amplitude at Specific Frequencies
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.meas AC voltage_amplitude_1kHz FIND V(out) AT 1kHz
.meas AC voltage_amplitude_10kHz FIND V(out) AT 10kHz
.meas AC current_amplitude_1kHz FIND I(C1) AT 1kHz
.meas AC current_amplitude_10kHz FIND I(C1) AT 10kHz

.end

Expected output (SPICE Output Log):

voltage_amplitude_1khz: V(out) =(-3.00607194349dB,-44.9720966632°) at 1000
voltage_amplitude_10khz: V(out) =(-20.0348374361dB,-84.28387881°) at 10000
current_amplitude_1khz: I(C1) =(-63.0145320899dB,45.0279033368°) at 1000
current_amplitude_10khz: I(C1) =(-60.0432975825dB,5.71612119002°) at 10000

Notes:

  • Default format displays results in dB and phase
  • The FIND ... AT syntax measures the value at exactly the specified frequency

  • Both voltage and current measurements can be performed using V(node) and I(component) syntax

Find the Amplitude at a Specific Frequency (Linear Format)

Complete netlist:

* RC Low-Pass Filter - Find Amplitude at Specific Frequency (Linear)
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.options meascplxfmt=polar

.meas AC amplitude_1kHz FIND V(out) AT 1kHz
.meas AC amplitude_10kHz FIND V(out) AT 10kHz

.end

Expected output (SPICE Output Log):

amplitude_1khz: V(out) =(0.707451061927,-44.9720966632°) at 1000
amplitude_10khz: V(out) =(0.0995997224501,-84.28387881°) at 10000

Notes:

  • .options meascplxfmt=polar displays measurements in linear magnitude and phase format
  • Default format (without this option) displays measurements in dB and phase
  • The FIND ... AT syntax measures the value at exactly the specified frequency

Measure Amplitude at Specific Frequency (Cartesian Format)

Complete netlist:

* RC Low-Pass Filter - Measure Amplitude at Specific Frequencies (Cartesian)
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.options meascplxfmt=cartesian

.meas AC amplitude_1kHz FIND V(out) AT 1kHz
.meas AC amplitude_10kHz FIND V(out) AT 10kHz

.end

Expected output (SPICE Output Log):

amplitude_1khz: V(out) =(0.500487005022,-0.499999762826) at 1000
amplitude_10khz: V(out) =(0.00992010471214,-0.0991044713151) at 10000

Notes:

  • .options meascplxfmt=cartesian displays measurements in real + imaginary format

Find DC Gain (Gain at Lowest Frequency)

Complete netlist:

* RC Low-Pass Filter - Find DC Gain
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.meas AC DC_gain FIND mag(V(out)) AT 1Hz

.end

Expected output (SPICE Output Log):

dc_gain: mag(V(out)) =(-4.33449074446e-06dB,0°) at 1

Find -3dB Cutoff Frequency

Complete netlist:

* RC Low-Pass Filter - Find Cutoff Frequency
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

* Basic method using magnitude
.meas AC cutoff_freq WHEN mag(V(out)) = 1/sqrt(2)

* Basic method using phase
.meas AC cutoff_freq2 WHEN ph(V(out)) = -45

* Basic method using real
.meas AC cutoff_freq3 WHEN re(V(out)) = .5

* Basic method using imaginary
.meas AC cutoff_freq4 WHEN im(V(out)) = -.499999

* Robust method (relative to DC gain)
.meas AC dc_gain FIND mag(V(out)) AT 1
.meas AC cutoff_freq5 WHEN mag(V(out)) = dc_gain/sqrt(2)

.end

Expected output (SPICE Output Log):

cutoff_freq: mag(V(out)) =1/sqrt(2) AT 1000.97471156
cutoff_freq2: ph(V(out)) =-45 AT 1000.99644414
cutoff_freq3: re(V(out)) =.5 AT 1000.98546328
cutoff_freq4: im(V(out)) =-.499999 AT 1000.14647293
dc_gain: mag(V(out)) =(-4.33449074446e-06dB,0°) at 1
cutoff_freq5: mag(V(out)) =dc_gain/sqrt(2) AT 1000.97571081

Notes:

  • Use mag(V(out)) instead of V(out) for AC magnitude measurements
  • -3dB point corresponds to 1/sqrt(2) or 0.707 of the DC gain
  • The robust method first measures DC gain, then finds cutoff relative to it

Measure Phase at Specific Frequency

Complete netlist:

* RC Low-Pass Filter - Measure Phase
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.options meascplxfmt=polar

.meas AC phase_1kHz FIND ph(V(out)) AT 1kHz

.end

Expected output (SPICE Output Log):

phase_1khz: ph(V(out)) =(44.9720966632,180°) at 1000

Notes:

  • Phase is reported in linear polar form when using .options meascplxfmt=polar
  • (44.97, 180°) equates to -44.97° (magnitude at 180° = negative value)

Measure Phase at Specific Frequency - Default Reporting in dB

Complete netlist:

* RC Low-Pass Filter - Measure Phase (dB format)
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.meas AC phase_1kHz FIND ph(V(out)) AT 1kHz

.end

Expected output (SPICE Output Log):

phase_1khz: ph(V(out)) =(33.0588627093dB,180°) at 1000

Notes:

  • Without .options meascplxfmt=polar, phase is reported in dB format
  • The result shows the phase in terms of dB (which is likely not useful)

Find Frequency Where Phase = -45°

Complete netlist:

* RC Low-Pass Filter - Find Frequency at -45 Degrees Phase
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.meas AC f_45deg WHEN ph(V(out))=-45

.end

Expected output (SPICE Output Log):

f_45deg: ph(V(out))=-45 AT 1000.99644414

Calculate Slope

Complete netlist:

* RC Low-Pass Filter - Calculate Rolloff Rate
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.ac dec 100 1 1Meg

.meas AC gain_10kHz FIND mag(V(out)) AT 10kHz
.meas AC gain_100kHz FIND mag(V(out)) AT 100kHz
.meas AC rolloff PARAM {gain_100kHz/gain_10kHz}
* Should be close to -20dB/decade for first-order filter

.end

Expected output (SPICE Output Log):

gain_10khz: mag(V(out)) =(-20.0348374361dB,0°) at 10000
gain_100khz: mag(V(out)) =(-39.9919749731dB,0°) at 100000
rolloff: {gain_100kHz/gain_10kHz}=(-19.957137537dB,0°)

Measure Bandwidth (Between Two Frequencies)

Complete netlist:

* RLC Bandpass Filter - Measure Bandwidth
V1 in 0 AC 1
R1 out 0 100
L1 in n1 10m
C1 n1 out 253n

.ac dec 100 10 100k

.options meascplxfmt=polar

.meas AC f_lower WHEN mag(V(out))=1/sqrt(2) CROSS=1
.meas AC f_upper WHEN mag(V(out))=1/sqrt(2) CROSS=LAST
.meas AC bandwidth PARAM {f_upper-f_lower}

.end

Expected output (SPICE Output Log):

f_lower: mag(V(out))=1/sqrt(2)  AT 2467.09854574
f_upper: mag(V(out))=1/sqrt(2)  AT 4058.53869986
bandwidth: {f_upper-f_lower}=(1591.44015412,0°)

Find Maximum Output

Complete netlist:

* RLC Bandpass Filter - Find Peak Response
V1 in 0 AC 1
R1 out 0 100
L1 in n1 10m
C1 n1 out 253n

.ac dec 100 10 100k

.meas AC Vout_max MAX mag(V(out))
.meas AC freq_at_max WHEN mag(V(out))=Vout_max

.end

Expected output (SPICE Output Log):

vout_max: MAX(mag(V(out)))=(-0.000111442946874dB,0°) FROM 10 TO 100000
freq_at_max: mag(V(out))=Vout_max AT 3162.27766017

Quality Factor (for Bandpass Filters)

Complete netlist:

* RLC Bandpass Filter - Calculate Q Factor
V1 in 0 AC 1
R1 out 0 100
L1 in n1 10m
C1 n1 out 253n

.ac dec 100 10 100k

.options meascplxfmt=polar

.meas AC Vout_max MAX mag(V(out))
.meas AC f_center WHEN mag(V(out))=Vout_max
.meas AC f_3dB_low WHEN mag(V(out))=Vout_max/sqrt(2) CROSS=1
.meas AC f_3dB_high WHEN mag(V(out))=Vout_max/sqrt(2) CROSS=2
.meas AC bandwidth PARAM {f_3dB_high-f_3dB_low}
.meas AC Q_factor PARAM {f_center/bandwidth}

.end

Expected output (SPICE Output Log):

vout_max: MAX(mag(V(out)))=(0.999987169739,0°) FROM 10 TO 100000
f_center: mag(V(out))=Vout_max AT 3162.27766017
f_3db_low: mag(V(out))=Vout_max/sqrt(2)  AT 2467.08295647
f_3db_high: mag(V(out))=Vout_max/sqrt(2)  AT 4058.56400569
bandwidth: {f_3dB_high-f_3dB_low}=(1591.48104922,0°)
q_factor: {f_center/bandwidth}=(1.98700302571,0°)

.MEAS with Noise Analysis - Key Functions

Measurement Functions

Function Description
V(onoise) Total output-referred noise (V/√Hz)
V(inoise) Total input-referred noise (V/√Hz)
V(component) Noise contribution from specific component (V/√Hz)

Measurement Operations

Operation Description
FIND ... AT freq Find noise value at specific frequency
INTEG ... FROM f1 TO f2 Integrate noise over frequency range to get RMS value (V_rms)
MAX Find maximum noise value
WHEN condition Find frequency when condition is met
PARAM {expr} Calculate parameter from measured values

Best Practices:

  • Noise spectral density is in V/√Hz units
  • Integrated noise (using INTEG) returns V_rms
  • Use V(component) to measure individual component noise contributions
  • For parametric sweeps with .STEP, use .meas NOISE param_name PARAM {parameter} to record the stepped value

Noise Analysis .MEAS Examples

  1. Noise Density Comparison at Multiple Frequencies
  2. Component Noise Contribution
  3. Find Peak Noise Frequency
  4. Integrated Noise Over Bandwidth
  5. 1/f Corner Frequency
  6. Parametric Sweep of Resistor Value
  7. Inverting Op-Amp with Resistor Noise Contributions

Noise Density Comparison at Multiple Frequencies

Complete netlist:

* RC Low-Pass Filter - Noise at Multiple Frequencies
V1 in 0 AC 1
R1 in out 10k
C1 out 0 159nF

.noise V(out) V1 dec 100 1 1Meg

.meas NOISE noise_1Hz FIND V(onoise) AT 1Hz
.meas NOISE noise_1kHz FIND V(onoise) AT 1kHz
.meas NOISE noise_10kHz FIND V(onoise) AT 10kHz
.meas NOISE ratio_1kHz_to_10kHz PARAM {noise_1kHz/noise_10kHz}

.end

Expected output (SPICE Output Log):

noise_1hz: V(onoise) =1.28741728389e-08 at 1
noise_1khz: V(onoise) =1.28232802155e-09 at 1000
noise_10khz: V(onoise) =1.28867166937e-10 at 10000
ratio_1khz_to_10khz: {noise_1kHz/noise_10kHz}=9.95077374649

Notes:

  • Resistor thermal noise: V_n = √(4kTR) ≈ 12.87 nV/√Hz for R=10k at 300K
  • H(f) = 1/(1 + j·2πfRC), where f_c = 1/(2πRC) ≈ 100 Hz
  • Output noise: V(onoise) = V_n × H(f)
  • At f « f_c: full noise passes; at f » f_c: -20 dB/decade rolloff
  • Noise spectral density in V/√Hz units

Component Noise Contribution

Complete netlist:

* RC Low-Pass Filter - Component Noise Contributions
V1 in 0 AC 1
R1 in mid 1k
R2 mid out 9k
C1 out 0 159nF

.noise V(out) V1 dec 100 1 1Meg

.meas NOISE R1_noise FIND V(R1) AT 1Hz
.meas NOISE R2_noise FIND V(R2) AT 1Hz
.meas NOISE total_noise FIND V(onoise) AT 1Hz

.end

Expected output (SPICE Output Log):

r1_noise: V(R1) =4.07117095591e-09 at 1
r2_noise: V(R2) =1.22135128677e-08 at 1
total_noise: V(onoise) =1.28741728389e-08 at 1

Notes:

  • Individual component noise contributions can be measured separately
  • Thermal noise scales as √R: R2 (9k) generates 3× more noise than R1 (1k) since √9 = 3
  • Uncorrelated noise sources add via root sum squared: √(V_R1² + V_R2²) = √(4kT·(R1+R2)) = 10k equivalent
  • Total noise (12.87 nV/√Hz) matches a single 10k resistor, confirming √((4.07)² + (12.2)²) ≈ 12.87 nV/√Hz

Find Peak Noise Frequency

Complete netlist:

* RLC Bandpass Filter - Peak Noise Frequency
V1 in 0 AC 1
R1 in out 100
L1 out 0 10m
C1 out 0 253n

.noise V(out) V1 dec 100 10 100k

.meas NOISE max_output_noise MAX V(onoise)
.meas NOISE freq_at_peak WHEN V(onoise)=max_output_noise

.end

Expected output (SPICE Output Log):

max_output_noise: MAX(V(onoise))=1.28747801309e-09 FROM 10 TO 100000
freq_at_peak: V(onoise)=max_output_noise AT 3162.27766017

Notes:

  • Parallel LC circuit creates resonance at center frequency
  • Noise peaks at resonant frequency where impedance is maximum
  • Peak noise equals R1 thermal noise: √(4kTR) = √(4 × 1.38×10⁻²³ × 300 × 100) ≈ 1.287 nV/√Hz
  • Center frequency: f₀ = 1/(2π√(LC)) = 1/(2π√(10m × 253n)) ≈ 3162 Hz

Integrated Noise Over Bandwidth

Complete netlist:

* RC Low-Pass Filter - Integrated Noise Over Bandwidth
V1 in 0 AC 1
R1 in out 1k
C1 out 0 159nF

.noise V(out) V1 dec 100 10 100k

.meas NOISE integrated_noise INTEG V(onoise) FROM 10 TO 100k

.end

Expected output (SPICE Output Log):

integrated_noise: INTEG(V(onoise) )=1.60413860951e-07 FROM 10 TO 100000

Notes:

  • INTEG calculates total RMS noise over specified bandwidth
  • Result is in V_rms, not V/√Hz
  • RC filter limits the noise bandwidth, reducing total integrated noise

1/f Corner Frequency

Complete netlist:

* MOSFET Amplifier - 1/f Corner Frequency
V1 in 0 AC 1
Vin gate 0 DC 2
M1 out gate 0 0 NMOS W=10u L=1u
Rd vdd out 10k
Vdd vdd 0 DC 5

.model NMOS NMOS (KP=200u VTO=0.7 LAMBDA=0.01 KF=1e-25 AF=1)

.noise V(out) V1 dec 100 1 100Meg

.meas NOISE noise_at_1Hz FIND V(onoise) AT 1Hz
.meas NOISE white_noise_floor FIND V(onoise) AT 100Meg
.meas NOISE corner_freq PARAM square({noise_at_1Hz/white_noise_floor})
.meas NOISE corner_freq2 WHEN V(onoise)={white_noise_floor*sqrt(2)} CROSS=1

.end

Expected output (SPICE Output Log):

noise_at_1hz: V(onoise) =9.31752538236e-07 at 1
white_noise_floor: V(onoise) =1.0712658538e-09 at 100000000
corner_freq: square({noise_at_1Hz/white_noise_floor})=756496.015133
corner_freq2: V(onoise)={white_noise_floor*sqrt(2)}  AT 750901.087711

Notes:

  • 1/f noise dominates at low frequencies in MOSFETs
  • KF and AF model parameters define flicker noise
  • Method 1 (PARAM): Uses 1/f decay at -10 dB/decade (voltage). Since V(onoise) ∝ 1/√f, then f_c = (V_1Hz/V_floor)²
  • Method 2 (RSS): Finds frequency where total noise = √2 × white noise floor. At corner frequency, 1/f noise equals white noise, so RSS = √(V_white² + V_white²) = √2 × V_white
  • Both methods give corner frequency ≈ 750 kHz where 1/f noise equals the white noise floor

Parametric Sweep of Resistor Value

Complete netlist:

* RC Low-Pass Filter - Parametric Sweep of R1
V1 in 0 AC 1
R1 in out {Rval}
C1 out 0 159nF

.step param Rval list 1k 5k 10k

.noise V(out) V1 dec 100 1 100k

.meas NOISE r_value PARAM Rval
.meas NOISE noise_1Hz FIND V(onoise) AT 1Hz
.meas NOISE integrated_noise INTEG V(onoise)

.end

Expected output (SPICE Output Log):

Measurement: r_value
  step	Rval
     1	1000
     2	5000
     3	10000

Measurement: noise_1hz
  step	V(onoise) 	at
     1	4.07137212832e-09	1
     2	9.1037559713e-09	1
     3	1.28741728389e-08	1

Measurement: integrated_noise
  step	INTEG(V(onoise))	FROM	TO
     1	1.60878171491e-07	1	100000
     2	1.61084970228e-07	1	100000
     3	1.6087915769e-07	1	100000

Notes:

  • .STEP directive creates multiple simulation runs
  • PARAM measurement records the swept parameter value
  • Thermal noise density for 1k resistor: √(4kTR) = √(4 × 1.38×10⁻²³ × 300 × 1000) ≈ 4.07 nV/√Hz
  • Noise at 1Hz scales as √R: doubling from 1k→5k→10k increases noise by √5 and √10
  • Cutoff frequency f_c = 1/(2πRC) changes with R1: higher R → lower f_c → more filtering
  • kT/C noise: √(kT/C) = √(1.38×10⁻²³ × 300 / 159×10⁻⁹) ≈ 161 nV_rms
  • Integrated noise equals kT/C noise (~161 nV_rms) regardless of R value - R cancels in the integration
  • kT/C derivation: Integrating thermal noise V_n = √(4kTR) through RC filter with f_c = 1/(2πRC) gives V_rms² = ∫₀^∞ 4kTR/(1+(f/f_c)²) df = 4kTR × (π/2)/(2πRC) = kT/C, therefore V_rms = √(kT/C)

Inverting Op-Amp with Resistor Noise Contributions

Complete netlist:

* Inverting Op-Amp - Noise Contributions

V1 NONINV 0 SINE(0 1 10K)
R1 INV 0 10K
R2 OUT INV 10K

Vdd vdd 0 DC 15
Vss vss 0 DC -15

XU1 NONINV INV vdd vss OUT level2 Avol=1Meg GBW=10Meg Slew=10Meg Ilimit=25m Rail=0 Vos=0 En=7.3n Enk=100 In=0 Ink=0 Rin=500Meg

.lib UniversalOpAmp2.lib

.noise V(out) V1 dec 100 1 1Meg

.meas NOISE total_noise_density FIND V(onoise) AT 1Meg
.meas NOISE R1_noise_density FIND V(R1) AT 1Meg
.meas NOISE R2_noise_density FIND V(R2) AT 1Meg
.meas NOISE low_freq_noise_density FIND V(onoise) AT 1

.end

Expected output (SPICE Output Log):

total_noise_density: V(onoise) =2.28844356798e-08 at 1000000
r1_noise_density: V(R1) =1.2624076895e-08 at 1000000
r2_noise_density: V(R2) =1.2624076895e-08 at 1000000
low_freq_noise_density: V(onoise) =1.47854748889e-07 at 1

Notes:

  • Unity-gain inverting amplifier (R2/R1 = 10k/10k = 1)
  • Op-amp configured with explicit parameters: En=7.3n (voltage noise), Enk=100 (1/f noise corner)
  • Noise gain: For inverting amplifier, noise gain = 1 + R2/R1 = 1 + 1 = 2 (different from signal gain of -1)
  • At 1 MHz (white noise):
    • Each 10k resistor: √(4kTR) = √(4 × 1.38×10⁻²³ × 300 × 10k) ≈ 12.87 nV/√Hz → 12.62 nV/√Hz at output
    • Op-amp noise at output: En × (noise gain) = 7.3 × 2 = 14.6 nV/√Hz
    • Total noise (RSS): √(12.62² + 12.62² + 14.6²) ≈ 22.9 nV/√Hz ✓
  • At 1 Hz: 1/f noise dominates with corner at Enk = 100 Hz, increasing total noise to ~148 nV/√Hz
  • All noise sources are referred to output

See also: SIMULATION-COMMANDS-REFERENCE.md for .MEASURE syntax and the full range of measurement keywords, MEASURE-DATABASE-REFERENCE.md for querying .STEP‘ed results from the SQLite .db file

Documentation source: github.com/analogdevicesinc/ltspice-reference