Abstract:
A phase-locked loop (PLL) includes a state machine programmed to automatically produce a set of control signals to select a charge-pump current and integrating capacitance value to automatically adjust a loop bandwidth of the PLL. A charge-pump DAC generates a charge-pump current of magnitude controlled by the state machine control signals. An integrator integrates the charge-pump output current to produce an integrated charge-pump output signal. The integrator has a plurality of capacitors switchably selected by control signals from the state machine to produce an integrating capacitance value. A voltage controlled oscillator (VCO) produces a PLL output frequency in response to the integrated charge-pump output signal.
Abstract:
A system for processing a signal includes a detector configured to detect a two-level stream of bits; a converter configured to generate a three-level control signal based on two adjacent values within the two-level stream of bits; and a switch configured to determine which of three different paths to couple a current source to based on a value of the three-level control signal. Thus, based on adjacent values of the output stream a three-level control signal is generated which controls coupling of the current source to one of three different paths. This type of three-level digital-to-analog converter can be, for example, part of the feedback loop of an analog-to-digital converter. Similar techniques can also be utilized in a multi-segment digital-to-analog converter in which each segment of the DAC is controlled by a 3-level control signal and the DAC is implement using PMOS devices. The current source for each DAC segment is diverted to ground, the M-node, or the P-node depending on the value of the 3-level control signal.
Abstract:
A simple bandgap current generator combines a PTAT (proportional to absolute temperature) base-emitter voltage (VBE) measured across two binary junction devices (ΔVBE=VBE1-VBE2) with a current that is varied by an nWell resistor with a positive temperature coefficient to produce a CTAT (complementary to absolute temperature) current instead of PTAT reference current. One of the base-emitter voltages is constrained to be VBE1=VBE(1-βT). This reduces the temperature dependency of a reference current generated by the bandgap generator. This reference current may be used to generate a bandgap reference voltage by adding an IR drop to a diode voltage or to a base-emitter voltage. The simple bandgap circuit is significantly smaller in size than a precision bandgap circuit, but still provides a voltage and/or a current reference signal having a good accuracy.
Abstract:
An analog-to-digital conversion system and method includes, for example, a comparator for sampling an analogy quantity during a sampling period and for performing a series of bit-wise conversions on the sampled analog sample during a conversion period, where each bit-wise conversion occurs during a respective bit-wise conversion cycle in which successive bits of a sample are successively determined during a respective bit conversion cycle and in which a predetermined number of bit-wise conversions are to be performed. A clock generator is arranged for generating a clock signal for clocking the converter during the conversion period, wherein each bit conversion cycle includes a reset period having a first length and an amplification period having a second length, wherein one of the first and second lengths is dynamically selected.
Abstract:
A simple bandgap current generator combines a PTAT (proportional to absolute temperature) base-emitter voltage (VBE) measured across two binary junction devices (ΔVBE=VBE1−VBE2) with a current that is varied by an nWell resistor with a positive temperature coefficient to produce a CTAT (complementary to absolute temperature) current instead of PTAT reference current. One of the base-emitter voltages is constrained to be VBE1=VBE(1βT). This reduces the temperature dependency of a reference current generated by the bandgap generator. This reference current may be used to generate a bandgap reference voltage by adding an IR drop to a diode voltage or to a base-emitter voltage. The simple bandgap circuit is significantly smaller in size than a precision bandgap circuit, but still provides a voltage and/or a current reference signal having a good accuracy.
Abstract:
A system for processing a signal includes a detector configured to detect a two-level stream of bits; a converter configured to generate a three-level control signal based on two adjacent values within the two-level stream of bits; and a switch configured to determine which of three different paths to couple a current source to based on a value of the three-level control signal. Thus, based on adjacent values of the output stream a three-level control signal is generated which controls coupling of the current source to one of three different paths. This type of three-level digital-to-analog converter can be, for example, part of the feedback loop of an analog-to-digital converter. Similar techniques can also be utilized in a multi-segment digital-to-analog converter in which each segment of the DAC is controlled by a 3-level control signal and the DAC is implement using PMOS devices. The current source for each DAC segment is diverted to ground, the M-node, or the P-node depending on the value of the 3-level control signal.