Abstract: A circuit includes an amplifier having first and second inputs and an output, and a feedback circuit configured to generate a feedback voltage in response to a voltage at the output of the amplifier. The feedback circuit is coupled to the first input of the amplifier to provide the feedback voltage to the first input of the amplifier. An output circuit is configured to generate a variable bias current in response to the voltage at the output of the amplifier. A switch circuit is configured to switch the second input of the amplifier from receiving a first reference voltage during a first mode of operation to receiving a second reference voltage during a second mode of operation.

Abstract: A transmission gate circuit for use, for example, as a switching element of an analog multiplexer, includes an input configured to receive an input signal, an output and a control input configured to receive a switch control signal. A transmission gate switch is coupled between the input and the output. A level shifting circuit generates a level shifted switch control signal from the switch control signal, and applies that level shifted switch control signal to a control terminal of the transmission gate switch. The control terminal of the transmission gate switch can instead receive the switch control signal in situations where a voltage of the input signal is suitably high to support linear operation of the transmission gate switch.

Abstract: A circuit includes an amplifier having first and second inputs and an output, and a feedback circuit configured to generate a feedback voltage in response to a voltage at the output of the amplifier. The feedback circuit is coupled to the first input of the amplifier to provide the feedback voltage to the first input of the amplifier. An output circuit is configured to generate a variable bias current in response to the voltage at the output of the amplifier. A switch circuit is configured to switch the second input of the amplifier from receiving a first reference voltage during a first mode of operation to receiving a second reference voltage during a second mode of operation.

Abstract: An analog to digital converter (ADC) includes a conversion circuit digitizing an input analog signal to produce an output digital signal. A current generator generates a constant bias current. A current mirror circuit includes an input transistor receiving the constant bias current, an output transistor in a mirroring relationship with the input transistor and generating a variable bias current, and a parallel transistor circuit selectively coupling a parallel transistor in parallel with the input transistor or the output transistor in response to a control signal. The control signal is representative of the conversion rate of the ADC. A buffer generates a common mode voltage for use by the conversion circuit, from the variable bias current.

Abstract: An analog to digital converter (ADC) includes a conversion circuit digitizing an input analog signal to produce an output digital signal. A current generator generates a constant bias current. A current mirror circuit includes an input transistor receiving the constant bias current, an output transistor in a mirroring relationship with the input transistor and generating a variable bias current, and a parallel transistor circuit selectively coupling a parallel transistor in parallel with the input transistor or the output transistor in response to a control signal. The control signal is representative of the conversion rate of the ADC. A buffer generates a common mode voltage for use by the conversion circuit, from the variable bias current.

Abstract: Threshold detection for load current on a bus involves generating an output current representative of the load current using a transconductance circuit, sampling the output current during a quiescent phase of the bus to produce a sample current, generating a compensation current that is proportional to the transconductance gain associated with the transconductance circuit, where the compensation current is a function of the sample current, combining the output current, the sample current, the compensation current, and a reference current representative of a threshold value for the load current to produce a combined current, and using a discriminator during an active phase of the bus to output a first value when the sum current exceeds the threshold value and a second value when the combined current is less than the threshold value.

Abstract: A level shifter includes a latch having first and second branches, first and second outputs, first and second control switches in series between the respective branches and outputs, and a controller receiving first and second output signals and outputting first and second control signals to the first and second control switches for controlling activation thereof. In an initial state, the first output signal is in the first state, the first control switch is activated, the second output signal is in the second state, and the second control switch is deactivated. In a final state, the first output signal is in the second state, the first control switch is deactivated, the second output signal is in the first state, and the second control switch is activated. The controller changes the first and second control signals only after the first and second output signals reach the respective second and first states.

Abstract: In an infusion pump operable to deliver fluid to a patient at a programmed therapy flow rate, air-in-line sensing is improved by commanding the pumping mechanism to deliver a bolus volume of fluid at a flow rate higher than the therapy flow rate when an uninterrupted volume of air is detected that exceeds a first threshold. In many cases, the bolus will be effective to clear microbubbles from an observation zone of the air-in-line sensor to avoid an air-in-line alarm condition. If the uninterrupted volume of air continues to grow beyond a second threshold in spite of the bolus, then an alarm may be triggered. The invention reduces false alarms.

Abstract: A level shifter includes a latch having first and second branches, first and second outputs, first and second control switches in series between the respective branches and outputs, and a controller receiving first and second output signals and outputting first and second control signals to the first and second control switches for controlling activation thereof. In an initial state, the first output signal is in the first state, the first control switch is activated, the second output signal is in the second state, and the second control switch is deactivated. In a final state, the first output signal is in the second state, the first control switch is deactivated, the second output signal is in the first state, and the second control switch is activated. The controller changes the first and second control signals only after the first and second output signals reach the respective second and first states.

Abstract: Threshold detection for load current on a bus involves generating an output current representative of the load current using a transconductance circuit, sampling the output current during a quiescent phase of the bus to produce a sample current, generating a compensation current that is proportional to the transconductance gain associated with the transconductance circuit, where the compensation current is a function of the sample current, combining the output current, the sample current, the compensation current, and a reference current representative of a threshold value for the load current to produce a combined current, and using a discriminator during an active phase of the bus to output a first value when the sum current exceeds the threshold value and a second value when the combined current is less than the threshold value.

Abstract: In an infusion pump operable to deliver fluid to a patient at a programmed therapy flow rate, air-in-line sensing is improved by commanding the pumping mechanism to deliver a bolus volume of fluid at a flow rate higher than the therapy flow rate when an uninterrupted volume of air is detected that exceeds a first threshold. In many cases, the bolus will be effective to clear microbubbles from an observation zone of the air-in-line sensor to avoid an air-in-line alarm condition. If the uninterrupted volume of air continues to grow beyond a second threshold in spite of the bolus, then an alarm may be triggered. The invention reduces false alarms.