Abstract:
An integrated circuit incorporating a bias circuit for a current-controlled oscillator (ICO) with improved power supply rejection ratio (PSRR) is described. The bias circuit for the ICO includes two error amplifiers. The first error amplifier regulates the bias voltage, VBN, referenced to a ground supply (GND). The second error amplifier regulates the bias voltage, VBP, referenced to a positive power supply (VDD). The VBP and VBN bias voltages have improved PSRR relative to conventional ICO bias circuits for noise injected into VDD and GND.
Abstract:
A digital-to-analog converter, RF transmit channel and method, for converting a digital signal of N bits having a set M of most significant bits and a set L of least significant bits to an analog signal, are disclosed. The digital signal defines a set of coded values which are converted to analog values and modulated on to a RF signal. The digital-to-analog converter includes a plurality of switches and an output stage, for providing at least a first differential output signal and a second differential output signal. The output stage modifies currents received from the plurality of switches, such that the value of the average output current of the first and second differential outputs signals is steered to a relatively low current value at the mid-point of the coded values.
Abstract:
A circuit for digital-to-analog conversion is described. The circuit includes a digital-to-analog converter (DAC). The DAC includes a double cascaded current source and a differential current-mode switch (DCMS). The circuit further includes a direct current (DC) offset stage. The circuit also includes a load attenuator. The double cascaded current source may be between the DCMS and a rail voltage.
Abstract:
Techniques for dynamically selecting circuit elements to combat mismatches are described. In one design, an apparatus includes first, second, and third circuits. The first circuit receives input data and provides first signals that are asserted based on the input data, e.g., with thermometer decoding. The second circuit receives the first signals and provides second signals used to select circuit elements, e.g., current sources, capacitors, resistors, etc. The third circuit generates a control for the second circuit, and the second circuit maps the first signals to the second signals based on this control. In one design, the second circuit includes a set of multiplexers and a control circuit. The multiplexers provides the first signals, circularly rotated by an amount determined by the control, as the second signals. The control circuit accumulates control data (e.g., the input data, pseudo-random data, or a fixed value) with the current control value to obtain new control value.
Abstract:
A high-speed, high-accuracy DAC has multiple current switches. Each current switch includes a current source that provides a reference current, first and second circuit elements that couple to the current source, and first and second transistors that couple to the first and second circuit elements, respectively. The first transistor provides the reference current to a first output when enabled, and the second transistor provides the reference current to a second output when enabled. The first and second circuit elements provide source degeneration for the first and second transistors, extend the linear operating region for these transistors, and may be implemented with either transistors that are always turned on or resistors. The first and second transistors and the first and second circuit elements may be P-channel field effect transistors (P-FETs), N-channel field effect transistors (N-FETs), or transistors of some other type.
Abstract:
A buffer amplifier has a power on state and a sleep state. During regular operation a coupling state of a load to an output node is detected using feedback voltage. In a sleep mode and in a power collapse mode a detection current is injected into the output node, to produce a voltage, and the coupling state of the load is detected from the voltage. Optionally, the detection current and detecting of the voltage on the output node is enables by a low duty cycle clock. Optionally, signals generated in detecting the coupling state are qualified through a debounce circuit.
Abstract:
According to at least one embodiment of the invention, an apparatus may include first, second and third circuits. The first circuit receives input data and provides a plurality of first signals asserted based on the input data. The second circuit receives the plurality of first signals and provides a plurality of second signals used to select a plurality of circuit elements. The third circuit generates a control for the second circuit using a fractional data weight of the input data, the second circuit mapping the plurality of first signals to the plurality of second signals based on the control from the third circuit.
Abstract:
An output stage (123) includes two transistors (T3, T4) (switching transistor, and biasing transistor) coupled in series in a pullup current path between a VDDA node and an output node, (120) and also includes two transistors (Tl, T2) (switching transistor and biasing transistor) coupled in series in a pulldown current path between the output node (121) and a ground node. Providing the biasing transistors (T2,T4) reduces the maximum voltage dropped across the transistors, thereby allowing the transistors to have lower breakdown voltages than VDDA. An adaptive biasing circuit (26) adjusts the gate voltage on a biasing transistor (T2,T4) based on the output node (121) voltage. If the output voltage is in a midrange, then the gate voltage is set farther away from a rail voltage in order to reduce voltage stress. If the output voltage is in a range closer to the rail voltage, then the gate voltage is set closer to the rail voltage, thereby facilitating rail-to-rail output voltage swings.
Abstract:
A packaging case for disposable compressed tissues is provided, which includes: a first accommodation portion which accommodates liquid; a second accommodation portion which has a stepped portion on the upper portion of the first accommodation portion so that the cross- sectional area of the second accommodation portion is larger than that of the first accommodation portion, and is partitioned from the first accommodation portion by a separable film which is thermally fused on the stepped portion by a thermal fusion operation, to thus ac¬ commodate tissues which have been compressed and dried; and a cover film which covers the upper portion of the second accommodation portion, wherein a bursting strength of the cover film is larger than that of the separable film when pressurized, so that the separable film is bursted before the cover film is bursted when pressurized.
Abstract:
Circuits and methods for compensating variation in an amplitude-regulated oscillator are provided. In one example, the oscillator includes a diode clamp having back-to-back diode-connected transistors with body terminals. Circuits and methods modulate a body-source voltage of the diode-connected transistors to compensate for process, temperature, and voltage variation.