In a circuit for DC-DC voltage converters, an amplifier has first and second inputs coupled to a reference voltage terminal and an output voltage terminal, respectively. A comparator has first and second inputs coupled to an amplifier output and a switching terminal, respectively. A logic circuit has inputs coupled to the comparator output and a clock terminal. A driver circuit has first and second inputs coupled to first and second logic outputs, respectively. A first transistor having a first control terminal coupled to the first driver output is coupled between a supply voltage terminal and the switching terminal. A second transistor is coupled between the switching terminal and a ground terminal, and has a second control terminal coupled to the second driver output. A threshold detection circuit is configured to provide a threshold signal responsive to a current through the second transistor crossing a current threshold.

In a circuit for DC-DC voltage converters, an amplifier has first and second inputs coupled to a reference voltage terminal and an output voltage terminal, respectively. A comparator has first and second inputs coupled to an amplifier output and a switching terminal, respectively. A logic circuit has inputs coupled to the comparator output and a clock terminal. A driver circuit has first and second inputs coupled to first and second logic outputs, respectively. A first transistor having a first control terminal coupled to the first driver output is coupled between a supply voltage terminal and the switching terminal. A second transistor is coupled between the switching terminal and a ground terminal, and has a second control terminal coupled to the second driver output. A threshold detection circuit is configured to provide a threshold signal responsive to a current through the second transistor crossing a current threshold.

A biosensor for an analyte monitoring system. In one embodiment, the biosensor includes a cascode common source transimpedance amplifier circuit, an analog to digital converter, and an output circuit. The cascode common source transimpedance amplifier circuit is configured to receive an electrical current generated by an electrochemical reaction of an analyte on a test strip. The cascode common source transimpedance amplifier circuit is also configured to convert the electrical current to an analog voltage signal. The analog to digital converter is configured to convert the analog voltage signal to a digital voltage signal. The output circuit is configured to transmit a signal indicating a measured level of the analyte based on the digital voltage signal.

A biosensor for an analyte monitoring system. In one embodiment, the biosensor includes a cascode common source transimpedance amplifier circuit, an analog to digital converter, and an output circuit. The cascode common source transimpedance amplifier circuit is configured to receive an electrical current generated by an electrochemical reaction of an analyte on a test strip. The cascode common source transimpedance amplifier circuit is also configured to convert the electrical current to an analog voltage signal. The analog to digital converter is configured to convert the analog voltage signal to a digital voltage signal. The output circuit is configured to transmit a signal indicating a measured level of the analyte based on the digital voltage signal.

Voltage-to-current converters that include two current mirrors are disclosed. In an example voltage-to-current converter each current mirror is a complementary current mirror in that one of its input and output transistors is a P-type transistor and the other one is an N-type transistor. Such voltage-to-current converters may be implemented using bipolar technology, CMOS technology, or a combination of bipolar and CMOS technologies, and may be made sufficiently compact and accurate while operating at sufficiently low voltages and consuming limited power.

A wide voltage trans-impedance amplifier includes a first P-channel metal oxide semiconductor (PMOS) transistor PM1, a second PMOS transistor PM2, a third PMOS transistor PM3, a fourth PMOS transistor PM4, a fifth PMOS transistor PM5, a first bias voltage VB1, a second bias voltage VB2, a third bias voltage VB3, a first N-channel metal oxide semiconductor (NMOS) transistor NM1, and a second NMOS transistor NM2. A common-gate amplifier detects a change of an input voltage, and a negative feedback is constructed by injecting a current into a current mirror to achieve a low input impedance. The trans-impedance amplifier uses a common-gate amplifier to monitor an input voltage and uses a current mirror to perform the transconductance enhancement on an input transistor, while ensuring a relatively high loop gain.

A balun is disclosed and includes a dielectric substrate defining a first surface and a second surface. The balun includes a first output port including a first output ground portion and first output power portion; a second output port including a second output ground portion and a second output power portion; and an input port including an input ground portion and input power portion. The first output ground portion, the second output ground portion, and the input ground portion are coupled at a ground junction portion. The first output power portion, the second output power portion, and the input power portion are coupled at a power junction portion. The first output power portion, the second output power portion, and the input power portion are positioned on the first surface. The first output ground portion, the second output ground portion, and the input ground portion are positioned on the second surface.

A balun is disclosed and includes a dielectric substrate defining a first surface and a second surface. The balun includes a first output port including a first output ground portion and first output power portion; a second output port including a second output ground portion and a second output power portion; and an input port including an input ground portion and input power portion. The first output ground portion, the second output ground portion, and the input ground portion are coupled at a ground junction portion. The first output power portion, the second output power portion, and the input power portion are coupled at a power junction portion. The first output power portion, the second output power portion, and the input power portion are positioned on the first surface. The first output ground portion, the second output ground portion, and the input ground portion are positioned on the second surface.

Disclosed is a voltage detector and a communication circuit capable of detecting a low input voltage. The voltage detector includes: an alternating-current coupling circuit generating a first and a second input voltages according to a source input voltage; a feedback amplifier outputting a branch current according to a sink current including the branch current, and determining an output voltage according to the first input voltage and the amount of the branch current; and an auxiliary circuit outputting the amount of the sink current according to the second input voltage. When the sink current increases as the second input voltage rises, the branch current also increases, so that the output voltage not only rises as the first input voltage rises but also rises as the branch current increases. This feature allows a lower input voltage to be detectable by the detection of the risen output voltage.

Disclosed is a voltage detector and a communication circuit capable of detecting a low input voltage. The voltage detector includes: an alternating-current coupling circuit generating a first and a second input voltages according to a source input voltage; a feedback amplifier outputting a branch current according to a sink current including the branch current, and determining an output voltage according to the first input voltage and the amount of the branch current; and an auxiliary circuit outputting the amount of the sink current according to the second input voltage. When the sink current increases as the second input voltage rises, the branch current also increases, so that the output voltage not only rises as the first input voltage rises but also rises as the branch current increases. This feature allows a lower input voltage to be detectable by the detection of the risen output voltage.