Abstract: This document discusses, among other things, a system and method for offsetting reverse-bias leakage of a high impedance bias network. In an example, an apparatus includes an anti-parallel diode pair coupled between a signal node and a common-mode node. The anti-parallel diode pair can include a first diode and a second diode coupled to the first diode. A third diode can be coupled between a supply node and the signal node, and the third diode can be sized to compensate for a parasitic diode junction of the anti-parallel diode pair.

Abstract: Apparatus and methods for an integrated circuit, single ended-to-differential amplifier are provided. In an example, the amplifier can include an amplifier circuit having a first input configured to receive a single-ended signal, a second input, and a differential output configured to provide an amplified representation of the single-ended signal. The amplifier can include a filter circuit configured to balance a common-mode voltage between the first and second inputs of the amplifier circuit. The filter circuit can include a common-mode input configured to receive the common-mode voltage, a first impedance network coupled between the common-mode input and the first input of the amplifier circuit, and a second impedance network coupled between the common-mode input and the second input of the amplifier circuit. The filter circuit can provide a low frequency pole below 1 hertz.

Abstract: This document discusses, among other things, an amplifier circuit including first and second amplifiers configured to receive an input signal and to provide a differential output signal using a feedback loop including a transconductance amplifier. A non-inverting input of a first amplifier can be configured to receive an input signal. The feedback loop can be configured to receive the outputs from the first and second amplifiers and to provide a feedback signal to the non-inverting input of the second amplifier, for example, to reduce a DC offset error or to increase a dynamic range of the amplifier circuit.

Abstract: An over-current protection circuit is disclosed that provides a current limit threshold using resistors in the path of a scaled mirror current of a load current. The protective circuit has a first state that passes a supply source to a device, but when the threshold is reached the circuit becomes a feedback circuit that allows only a set final current to be passed to the device. When the load current reaches the threshold, the mirror current reaches a corresponding threshold that triggers a comparator and circuitry that then limits and fold backs the load current.

Abstract: This document discusses, among other things, a multiple accessory detection apparatus and methods for identifying accessories coupled to a multi-pin connector of an electronic device. The apparatus can include a first reference generator, a second reference generator, a plurality of switches to couple an output of the second generator to an accessory device and a comparator. The comparator can generate identifying information about the accessory device using the reference information received from the first reference generator and test information received using the second reference generator.

Abstract: The present invention employs identically sized mirror transistors arrange in groups that may be preferentially addressed and activated to determine the value of a resistor. Known current are directed through the resistor, and the voltage developed is measured by comparing against a reference voltage. The current is increased or decreased by the least significant value until the voltage across the resistor matches the reference voltage. A successive approximation or other known technique may be used instead. A reference current is developed that temperature stable and that is trimmed when manufactured to reduce process effects. The reference voltage may be constructed to be independent form a local power source so that the system is relatively independent of process, voltage and temperature, PVT.

Abstract: Apparatus and methods for an integrated circuit, high-impedance network are provided. In an example, the network can include an anti-parallel diode pair coupled between first and second nodes. The anti-parallel diode pair can include a first diode including a P+/NWELL junction and a second diode including N+/PWELL junction. In an example, the first diode and the second diode can include a common substrate.

Abstract: Apparatus and methods for an integrated circuit, single ended-to-differential amplifier are provided. In an example, the amplifier can include an amplifier circuit having a first input configured to receive a single-ended signal, a second input, and a differential output configured to provide an amplified representation of the single-ended signal. The amplifier can include a filter circuit configured to balance a common-mode voltage between the first and second inputs of the amplifier circuit. The filter circuit can include a common-mode input configured to receive the common-mode voltage, a first impedance network coupled between the common-mode input and the first input of the amplifier circuit, and a second impedance network coupled between the common-mode input and the second input of the amplifier circuit. The filter circuit can provide a low frequency pole below 1 hertz.

Abstract: A control circuit generates an output based on the first signal and the second signal by encoding the output to be a multi-state signal having at least three states. A magnitude of the multi-state signal generated by the controller varies depending on binary states of the first signal and the second signal. The controller utilizes the output (i.e., the multi-state signal) to control a switching circuit. A driver circuit receives the output generated by the control circuit. In one embodiment, the multi-state signal has more than two different logic states. The driver decodes the multi-state signal for generating signals to control switches in the switching circuit. One signal generated by the driver circuit is a pulse width modulation signal; another signal generated by the driver circuit is an enable/disable signal.

Abstract: This document discusses, among other things, a multiple accessory detection apparatus and methods for identifying accessories coupled to a multi-pin connector of an electronic device. The apparatus can include a first reference generator, a second reference generator, a plurality of switches to couple an output of the second generator to an accessory device and a comparator. The comparator can generate identifying information about the accessory device using the reference information received from the first reference generator and test information received using the second reference generator.

Abstract: This document discusses, among other things, a system and method for offsetting reverse-bias leakage of a high impedance bias network. In an example, an apparatus includes an anti-parallel diode pair coupled between a signal node and a common-mode node. The anti-parallel diode pair can include a first diode and a second diode coupled to the first diode. A third diode can be coupled between a supply node and the signal node, and the third diode can be sized to compensate for a parasitic diode junction of the anti-parallel diode pair.

Abstract: A control circuit generates an output based on the first signal and the second signal by encoding the output to be a multi-state signal having at least three states. A magnitude of the multi-state signal generated by the controller varies depending on binary states of the first signal and the second signal. The controller utilizes the output (i.e., the multi-state signal) to control a switching circuit. A driver circuit receives the output generated by the control circuit. In one embodiment, the multi-state signal has more than two different logic states. The driver decodes the multi-state signal for generating signals to control switches in the switching circuit. One signal generated by the driver circuit is a pulse width modulation signal; another signal generated by the driver circuit is an enable/disable signal.

Abstract: An over-current protection circuit is disclosed that provides a current limit threshold using resistors in the path of a scaled mirror current of a load current. The protective circuit has a first state that passes a supply source to a device, but when the threshold is reached the circuit becomes a feedback circuit that allows only a set final current to be passed to the device. When the load current reaches the threshold, the mirror current reaches a corresponding threshold that triggers a comparator and circuitry that then limits and fold backs the load current.

Abstract: A control circuit generates an output based on the first signal and the second signal by encoding the output to be a multi-state signal having at least three states. A magnitude of the multi-state signal generated by the controller varies depending on binary states of the first signal and the second signal. The controller utilizes the output (i.e., the multi-state signal) to control a switching circuit. A driver circuit receives the output generated by the control circuit. In one embodiment, the multi-state signal has more than two different logic states. The driver decodes the multi-state signal for generating signals to control switches in the switching circuit. One signal generated by the driver circuit is a pulse width modulation signal; another signal generated by the driver circuit is an enable/disable signal.

Abstract: A circuit is described that when the power supply to circuits that control a pass transistor is at zero volts, the pass transistor configured as a voltage level translator remains off regardless of the voltages and changes in voltages at the ports connected to the pass transistor. Cross coupled transistors provide a mechanism where the higher of the port voltages is available to power circuitry that maintains the control input of the pass transistor in the off condition. The voltages at the ports may rise and fall relative to each other, but the control input of the pass transistor will keep the pass transistor off.

Abstract: A circuit is described that when the power supply to circuits that control a pass transistor is at zero volts, the pass transistor configured as a voltage level translator remains off regardless of the voltages and changes in voltages at the ports connected to the pass transistor. Cross coupled transistors provide a mechanism where the higher of the port voltages is available to power circuitry that maintains the control input of the pass transistor in the off condition. The voltages at the ports may rise and fall relative to each other, but the control input of the pass transistor will keep the pass transistor off.

Abstract: A control circuit generates an output based on the first signal and the second signal by encoding the output to be a multi-state signal having at least three states. A magnitude of the multi-state signal generated by the controller varies depending on binary states of the first signal and the second signal. The controller utilizes the output (i.e., the multi-state signal) to control a switching circuit. A driver circuit receives the output generated by the control circuit. In one embodiment, the multi-state signal has more than two different logic states. The driver decodes the multi-state signal for generating signals to control switches in the switching circuit. One signal generated by the driver circuit is a pulse width modulation signal; another signal generated by the driver circuit is an enable/disable signal.

Abstract: The present invention employs identically sized mirror transistors arrange in groups that may be preferentially addressed and activated to determine the value of a resistor. Known current are directed through the resistor, and the voltage developed is measured by comparing against a reference voltage. The current is increased or decreased by the least significant value until the voltage across the resistor matches the reference voltage. A successive approximation or other known technique may be used instead. A reference current is developed that temperature stable and that is trimmed when manufactured to reduce process effects. The reference voltage may be constructed to be independent form a local power source so that the system is relatively independent of process, voltage and temperature, PVT.

Abstract: Embodiments of the invention include an apparatus and method for continuously calibrating the frequency of a clock and data recovery (CDR) circuit. The apparatus includes a delay arrangement that generates a gating signal, and a gated voltage-controlled oscillator that is enabled by the gating signal. The gated voltage-controlled oscillator generates a recovered clock signal that is based on the data signal input to the CDR circuit. The apparatus also includes a frequency control loop that continuously calibrates the gated voltage-controlled oscillator in such a way that the frequency of the clock signal generated by the gated voltage-controlled oscillator continues to be one half of the period of the data bits in the input data signal and the clock signal remains synchronized to the center of the data state transitions of the input data signal. Alternatively, a secondary frequency control loop adjusts the amount of delay in the frequency control loop.

Abstract: Embodiments of the invention include an apparatus and method for continuously calibrating the frequency of a clock and data recovery (CDR) circuit. The apparatus includes a delay arrangement that generates a gating signal, and a gated voltage-controlled oscillator that is enabled by the gating signal. The gated voltage-controlled oscillator generates a recovered clock signal that is based on the data signal input to the CDR circuit. The apparatus also includes a frequency control loop that continuously calibrates the gated voltage-controlled oscillator in such a way that the frequency of the clock signal generated by the gated voltage-controlled oscillator continues to be one half of the period of the data bits in the input data signal and the clock signal remains synchronized to the center of the data state transitions of the input data signal. Alternatively, a secondary frequency control loop adjusts the amount of delay in the frequency control loop.