Source: https://guthlabs.ai/docs/instruments/bjt-bias-point-calculator-voltage-divider-bias/implementation/

instrument implementation / implementation-contract

# BJT Bias Point Calculator (Voltage Divider Bias) implementation

A source-bound implementation contract for BJT Bias Point Calculator (Voltage Divider Bias); deployment and executable qualification remain separate.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-with-binding-errata

**Evidence ID**: t5-165

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification has an undefined divider case when R1+R2=0, and its supplied active-region formula produces negative VCE values after the saturation boundary without defining a separate saturation model or clamp. Resistor-position conventions also materially change the result if R1 and R2 are mislabeled.

## Required corrections

````
[
  {
    "vector": 2,
    "field": "VB/IE/VCE",
    "wrong": "VB 2, IE 1.3, VCE 2.4",
    "correct": "VB 2.5, IE 1.8, VCE 1.4",
    "cause": "5×10/20 written as 2 in working; cascade"
  },
  {
    "vector": 4,
    "field": "VB_V",
    "wrong": 2,
    "correct": 2.5,
    "cause": "same slip, but v4 IE/VCE are consistent with the CORRECT VB=2.5 — only the VB field wrong"
  }
]
````

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "Vcc_V": 12,
    "R1_ohm": 47000,
    "R2_ohm": 10000,
    "RC_ohm": 2200,
    "RE_ohm": 1000,
    "beta": 100
  },
  "expected_outputs": {
    "VB_V": 2.105263158,
    "IE_A": 0.001405263158,
    "IC_A": 0.001405263158,
    "VCE_V": 7.503157895,
    "saturation_cutoff_check": "active under the simplified model"
  },
  "working": "VB=12·10000/(47000+10000)=120000/57000=2.105263158 V. VE=2.105263158−0.7=1.405263158 V. IE=VE/RE=1.405263158/1000=0.001405263158 A. IC≈IE=0.001405263158 A; β=100 is ignored by the supplied formula. VCE=12−0.001405263158·(2200+1000)=12−0.001405263158·3200=12−4.496842105=7.503157895 V."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/bjt-bias-point-calculator-voltage-divider-bias/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/bjt-bias-point-calculator-voltage-divider-bias/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/bjt-bias-point-calculator-voltage-divider-bias/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`

- `tranche errata record`