Abstract: A humidification system can include a heater base, a humidification chamber, and a breathing circuit. A cartridge can be removably coupled to the heater base. The cartridge can include various sensors, probes, sensor wire connectors, heater wire connectors, and/or other features. The cartridge can include features configured to mate with corresponding features on the humidification chamber and the heater base. The cartridge includes a memory, such as an EEPROM, or other suitable storage device. When the cartridge is installed on the heater base, the memory is electrically connected to a processor and/or memory of the heater base. Various models of cartridges can be produced for use with different humidification chambers, breathing circuits, and/or therapies. A connector can be configured to couple an inspiratory conduit to an outlet port of the humidification chamber. The connector can provide a pneumatic connection to the outlet port and an electrical connection to the cartridge.

Abstract: An example PWM includes a driver and a two-way oscillator. The oscillator includes, a first frequency adjust current source, a second frequency adjust current source, a capacitor, a switching reference and a comparator. The capacitor integrates a frequency adjust current by charging with the first frequency adjust current source. The capacitor subsequently integrates a second frequency adjust current by discharging with the second frequency adjust current source. The switching reference outputs a first reference voltage and a second reference voltage responsive to an oscillator signal. The comparator compares the output of the switching reference with a voltage on the capacitor. The first and second frequency adjust current sources vary the first and second frequency adjust currents to vary the frequency of the PWM signal to spread energy of switching harmonics over a frequency band and to reduce EMI.

Abstract: An example two-way integrator includes a first current source, a second current source, a first offset current source, a second offset current source, a capacitor, a switching reference and a comparator. The capacitor integrates a sum of a first input current and a first offset current by charging with both the first current source and the first offset current source. The capacitor subsequently integrates a sum of the second input current and the second offset current by discharging with both the second current source and the second offset current source. The switching reference outputs a first reference voltage and a second reference voltage responsive to pulses of a pulse signal. The comparator is coupled to compare the switching reference with a voltage on the capacitor.

Abstract: An example two-way integrator includes a first current source, a second current source, a first offset current source, a second offset current source, a capacitor, a switching reference and a comparator. The capacitor integrates a sum of a first input current and a first offset current by charging with both the first current source and the first offset current source. The capacitor subsequently integrates a sum of the second input current and the second offset current by discharging with both the second current source and the second offset current source. The switching reference outputs a first reference voltage and a second reference voltage responsive to pulses of a pulse signal. The comparator is coupled to compare the switching reference with a voltage on the capacitor.

Abstract: A pulse width modulator (PWM) includes a driver and a two-way integrator. The driver is coupled to output a first and a subsequent period of a PWM signal. Both the first and the subsequent periods include the PWM signal changing between first and second states. The two-way integrator is coupled to integrate an input current and coupled to generate a duty ratio signal in response to integrating the input current. The driver determines a duty factor of both the first and the subsequent periods by setting the PWM signal to the second state in response to the duty ratio signal. The two-way integrator includes a capacitor that integrates the input current during the first period by charging the capacitor and integrates the input current during the subsequent period by discharging the capacitor.

Abstract: A pulse width modulator (PWM) includes a driver and a two-way integrator. The driver is coupled to output a first and a subsequent period of a PWM signal. Both the first and the subsequent periods include the PWM signal changing between first and second states. The two-way integrator is coupled to integrate an input current and coupled to generate a duty ratio signal in response to integrating the input current. The driver determines a duty factor of both the first and the subsequent periods by setting the PWM signal to the second state in response to the duty ratio signal. The two-way integrator includes a capacitor that integrates the input current during the first period by charging the capacitor and integrates the input current during the subsequent period by discharging the capacitor.