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Fix Ripples runaway feedback bug

- Constrain the tanh approximation input to monotonic range
- Clamp filter cell voltages
tags/v1.4.0
Tyler Coy 2 years ago
parent
commit
597d8a6f16
1 changed files with 9 additions and 2 deletions
  1. +9
    -2
      src/Ripples/ripples.hpp

+ 9
- 2
src/Ripples/ripples.hpp View File

@@ -108,6 +108,9 @@ static const float kVCAOutputR = 100e3f;
// Saturation voltage at BJT collector
static const float kVtoICollectorVSat = -10.f;

// Opamp saturation voltage
static const float kOpampSatV = 10.6f;


class RipplesEngine
{
@@ -280,6 +283,8 @@ protected:
return dvout;
});

cell_voltage_ = simd::clamp(cell_voltage_, -kOpampSatV, kOpampSatV);

float lp1 = cell_voltage_[0];
float lp2 = cell_voltage_[1];
float lp4 = cell_voltage_[3];
@@ -344,10 +349,12 @@ protected:
const float kTemperature = 40.f; // Silicon temperature in Celsius
const float kKoverQ = 8.617333262145e-5;
const float kKelvin = 273.15f; // 0C in K
const float kVt = kKoverQ * (kTemperature + kKelvin);
const float kVt = kKoverQ * (kTemperature + kKelvin);
const float kZlim = 2.f * std::sqrt(3.f);

T vi = vp - vn;
T z = vi / (2 * kVt);
T zlim = kZlim;
T z = math::clamp(vi / (2 * kVt), -zlim, zlim);

// Pade approximant of tanh(z)
T z2 = z * z;


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